Wikipedia talk:WikiProject Elements/Archive 51

"Categories", and even their "color", over PT essence
This edit, detailing that neither enwiki's coloring nor enwiki's categorisation is that important over groups, periods, blocks in the PT, says enough. Here Sandbh undoes the statement. Enough. Sandbh does not OWN the PT. -DePiep (talk) 23:58, 2 October 2020 (UTC)
 * Hi . You keep changing FA Periodic table and its supporting features without crisp support. That is not acceptible. If you keep editing and behaving this way, I will have you blocked. -DePiep (talk) 00:12, 3 October 2020 (UTC)
 * Are you fine? -DePiep (talk) 00:14, 3 October 2020 (UTC)

I am tremendous, than you for asking. Are you OK? You seem to have gotten yourself into a pickle as a result of what is occurring at WP:ANI.

You too, do not WP:OWN anything.

I have changed the PT article a few times, following discussions here at WP:ELEM. There is no up front requirement to obtain consensus. The few comments for the first edit attracted suggestions and comments. There was no dissent. You reverted anyway.

The other edits I made concerning categories etc were followed by four editors who corrected some typos, and nothing else. Anyone of them could have changed my edits but chose not to. So five editors, including me, raised no concerns by their actions. As a fellow WP:ELEM member, you chose to effectively undo my work, without discussion. Of course, you are entitled to that but it does not, in my view, contribute to harmonious relationships within our project.

When you threaten to block me in circumstances where I make good faith edits, usually in the context of discussions here, I get rather upset. When you say that you will have me blocked when you have no intrinsic power to have me blocked, I get further upset. I would prefer you to raise your concerns here rather than threatening me or citing "no consensus obtained", when no such consensus needed to be obtained in the first place. Sandbh (talk) 07:25, 3 October 2020 (UTC)

On the order of categories, groups, block etc, I think I will follow chronological order: --- Sandbh (talk) 07:35, 3 October 2020 (UTC)
 * Metals, metalloids, nonmetals: The recognition of metals and nonmetals was around before the periodic table.
 * Categories: These were around before the periodic table e.g. Berzelius and the halogens (~1825)
 * Next would come groups and periods, per DIM circa 1869+
 * Then would come blocks, which seem to date from the time of Janet (1928?)
 * And there's the rub: historically these things were discovered back-to-front, because the more fundamental things require deeper and deeper drilling down. Mostly I suspect electronic structure and hence blocks, groups, and periods get explained before the periodic table is actually shown, because the former explain the latter. Then the trends, including the metal-to-nonmetal one, can be explained. Double sharp (talk) 11:31, 6 October 2020 (UTC)

A resonating abecedarian approach to the 18-column periodic table
I'm posting this in the context of our discussions re group 3, and related group configurations like He over Be.

Periodicity is approximate, not precise. Accordingly there is no fundamental requirement for each space in the periodic table to be occupied by just one element. Blurring is not prohibited.

The "non-problems" go away if groups 2 and 12 resonate between (i) Be-Mg-Ca-Sr-Ba-Ra; (ii) Be-Mg-Zn-Cd-Hg-Cn; (iii) He-Be-Mg-Ca-Sr-Ba-Ra; (iv) He-Be-Mg-Zn-Cd-Hg-Cn; and (v) Zn-Cd-Hg-Cn. This means group 18, too, is a resonator between (i) He-Ne-Ar-Kr-Xe-Rn and (ii) Ne-Ar-Kr-Xe-Rn.

Likewise, groups 3 and 13 resonate between (i) Sc-Y-La-Ac; (ii) Sc-Y-Gd-Cm; (iii) Sc-Y-Lu-Lr; (iv) B-Al-Ga-In-Tl; (v) H-B-Al-Ga-In-Tl; (vi) B-Al-Sc-Y-La-Ac; (vii) B-Al-Sc-Y-Gd-Cm; (viii) B-Al-Sc-Y-Lu-Lr; (ix) H-B-Al-Sc-Y-La-Ac; (x) H-B-Al-Sc-Y-Gd-Cm; and (xi) H-B-Al-Sc-Y-Lu-Lr.

H resonates across groups 1, 13, 14, and 17.

For the remaining ten groups, "one element one space" is a good enough approximation.

So there it is: eight groups (1-3; 12-14; 17-18) resonating, with twenty-four possible configurations; and ten fixed group (4-11; 15-16).

From the list below:
 * IUPAC is type HK;
 * Lu in group 3 is type K;
 * He-Be and group 3 as -Lu-Lr is type EK;
 * Jensen preferred a type CDK;
 * Pauling’s EN table is type N* (the * denotes an irregularity, since H is assigned to no group)

The most common table has all eight defaults.

The various resonances are like shadows on the wall in Plato’s cave. A nuanced understanding of the periodic table, and its variants, is appreciated by keeping this resonating abecedarian approach in mind.

THE 24 RESONANCES

Group 1 (2) [A]	H-Li-Na-K-Rb-Cs-Fr (default) [B]	Li-Na-K-Rb-Cs-Fr

Group 2/12 (5) [C]	Be-Mg-Ca-Sr-Ba-Ra (default) [D]	Be-Mg-Zn-Cd-Hg-Cn

[E]	He-Be-Mg-Ca-Sr-Ba-Ra [F]	He-Be-Mg-Zn-Cd-Hg-Cn

[G]	Zn-Cd-Hg-Cn (default)

Group 3/13 (11) [H]	Sc-Y-La-Ac (default) [J]	Sc-Y-Gd-Cm [K]	Sc-Y-Lu-Lr

[L]	B-Al-Ga-In-Tl (default) [M]	H-B-Al-Ga-In-Tl

[N]	B-Al-Sc-Y-La-Ac [P]	B-Al-Sc-Y-Gd-Cm [Q]	B-Al-Sc-Y-Lu-Lr

[R]	H-B-Al-Sc-Y-La-Ac [S]	H-B-Al-Sc-Y-Gd-Cm [T]	H-B-Al-Sc-Y-Lu-Lr

Group 14 (2) [U]	C-Si-Ge-Sn-Pb (default) [V]	H-C-Si-Ge-Sn-Pb

Group 17 (2) [W]	F-Cl-Br-I (default) [X]	H-F-Cl-Br-I

Group 18 (2) [Y]	He-Ne-Ar-Kr-Xe-Rn (default) [Z]	Ne-Ar-Kr-Xe-Rn

On this basis, the IUPAC table is fine, acknowledging they don't give sufficient context. In that sense it isn’t fine. Sandbh (talk) 06:02, 4 October 2020 (UTC)

Droog Andrey's 32-column table

 * Yes, almost all of these are part of the paradigm of secondary and tertiary relationships (see these two papers of Jensen.)
 * However, I think it's not restricted to the groups you're talking about. C-Si-Ti is briefly discussed by Greenwood and Earnshaw while they talk about the group 4 trends, and Mendeleev's table by being 8-column also shows such as it mixes the A and B groups: therefore, the elements appearing in group VI on his table are O, S, and then Cr, Se, Mo, Te, and so on. (Secondary relationship from S to Cr is well visible in maximum oxidation state; consider sulfate vs chromate.) This is equally what Rayner-Canham calls the Group (n) and Group (n + 10) linkage.
 * So, I feel that all these are additional "resonances" that are needed for a nuanced understanding. So the following is how I would deal with the issue. It's similar to what I've talked about on your talk page, though I go a bit more at length here since this is explicitly about the secondary relationships. Actually, a lot more at length. Sorry; there's a TL;DR at the end.
 * We can easily draw as Droog Andrey did the significantly useful ones:


 * For me, yes, blurring is prohibited, and periodicity is precise. To understand periodicity, in my opinion, we have to clearly define the bases. An element is defined by its atomic number and the structure of its electronic cloud. The first everyone agrees on, I hope; the second is less obvious, but I think we'll agree that it's important, because without it we would have no reason why the period lengths should be as they are and not something else. Note that I do not mean the chemically irrelevant ground-state gas-phase or condensed-phase configurations, but the set and total occupancy of the orbitals that can be involved in chemical bonding. For the d and f block elements, the first two, while standard, are really simply sweating the small stuff.
 * The periods come from the requirement that Z increase; the groups, from periodic recurrence of analogous outer electronic clouds. And the period break at the noble gases (and indeed their inertness in itself) comes from the large energy gap between np and (n+1)s subshells. Ergo, everything is fixed and precise. The place of an element on the periodic table, for me, is a direct reflexion of its innermost nature: its atomic number and its electronic structure (whence its block).
 * For example, consider, lutetium. Its position is successively fixed in this approach as follows. Firstly, having Z = 71, it must come between ytterbium (Z = 70) and hafnium (Z = 72) on the table. Then, having valence electronic shell structure (5d 6s 6p)3, it belongs in the d block (because it uses inner d orbitals but not inner f or g orbitals), and it belongs with other d block elements with analogously three valence electrons: scandium with (3d 4s 4p)3, yttrium with (4d 5s 5p)3, and lawrencium with (6d 7s 7p)3. Lanthanum, having instead the valence electronic shell structure (4f 5d 6s 6p)3, doesn't belong with them. If we allow La to stand there with the different shell structure, then questions will arise about aluminium (3s 3p)3 which also has chemical similarities, and that way lies either overcomplication or inconsistency in my view. If we repeat this for all elements, we fix everybody's position. (Regarding how this handles the problem of group 2, with magnesium (3s 3p)2, calcium (3d 4s 4p)2, and zinc (3d 4s 4p)12 resulting in no true higher homologue, we deal with this s block problem later.) So, I say: because of the importance of valence structure (it is behind what to a first approximation is 100% of chemistry humans deal with), in all contexts we should have Sc-Y-Lu shown as it is the primary relationship. However: lanthanum is also related to Sc and Y, because it likewise has three valence electrons. That's a kind of secondary relationship. And I also say that, because this also comes from the valence structure, in all contexts we should have Sc-Y-La also kept in mind as a secondary relationship. And exactly the same thing with aluminium, which we showed already. So, my viewpoint is: don't take any one thing and say "this is for this context, that is for that context, etc.", because all of them are valid for every context. We just need to know which ones are primary and which ones are secondary or tertiary.
 * Secondary and tertiary relationships can simply be explained separately. They are relationships between two elements which have the same number of valence electrons but are not in the same group. And tertiary relationships are relationships between two elements which have the same number of valence vacancies but are not in the same group. In general primary relationships are strongest, followed by secondary, followed by tertiary, but it's not a hard-and-fast rule (helium has no primary relationships, but its tertiary relationship is stronger than its secondary one). Because for group membership you need the analogous outer shell structure. So the general rule is that groups follow primary relationships whenever possible, and secondary relationships if there are no primary relationships (the latter situation only affects the s block).
 * While I strongly feel it is inconsistent to take Sc-Y-La alone (because any argument strong enough to do that, if applied elsewhere, tends to result in either Be-Mg-Zn, B-Al-Sc, or pulling Th out of the f block as well); as part of a unified, holistic conception of secondary and tertiary relationships, as just another colourful addition to the periodicity in the set {H-F-Cl, He-Ne-Ar, B-Al-Sc, Sc-Y-La, C-Si-Ti, Ti-Zr-Ce, N-P-V, V-Nb-Pr-Pa, O-S-Cr, Cr-Mo-(Nd)-U, F-Cl-Mn, Ca-Sr-Yb, Be-Mg-Zn}, I feel that it is perfectly correct and useful. For me, individual tables that take out one secondary or tertiary relationship and ignore all the others are harmful in how they make it seem like those are above the others; but a table that recognises them all is perfectly sound.
 * Some secondary or tertiary relationships will be strong, some will be weak, some will be essentially nonexistent, but that's all right; knowing which ones are more useful is a matter of chemical intuition. Primary relationships (the ones in the same group) can just as well be strong (Na-K), weak (Sn-Pb), or in extreme cases essentially nonexistent outside extreme conditions (He-Be, N-Bi, Ne-Og). But chemistry has never stopped us from putting Og in group VIIIp; that was never the basis. You deduce chemistry painstakingly, one step at a time, from the electronic structure which is the basis, not the other way round. There can also be relativistic secondary and tertiary relationships which occur when you get a pseudo-noble-gas configuration like Hg, Cn, or Fl; whence relationships like the "knight's move" ones, or things like At-Nh or Rn-Cn or Si-Og.
 * H over C might at a stretch be taken as an extra relationship, as both are half-filled. It is not a very strong relationship, but that's all right, there are weak ones at every class. There are a bunch of elements that end up being chemically similar without a real secondary or tertiary relationship, like Al and Fe. I'd create a class of quaternary relationships for these catch-alls. Diagonal relationships can also fit here, as they are basically the result of mutual cancellation of greater atomic size and greater atomic charge for polarising power (Li-Mg, Be-Al, B-Si being the most famous ones). Strong quaternary relationships might at least match valence (Al to Fe, Y to Gd); weak ones might not (H to C, diagonal relationships); but they all exist and are useful to keep in mind.
 * Here we have united most of Rayner-Canham's extra relationships under a single paradigm. I consider that a better approached to a nuanced understanding because of its power at generalisation. Now, without having to add more letters, we can immediately guess that period 8 is going to cause another split with secondary relationships of the first few superactinides to the early actinides, with the real homologues coming later. Predictive power is needed, not just descriptive power, in my opinion. To me, we should be able to say something as a prediction for the 8th period elements that should be just around the corner (hopefully I haven't jinxed it).
 * Notably, this partly explains why the group 3 dispute tends to go back and forth. Sc-Y-La and Sc-Y-Lu are both valid relationships of some kind. The problem is that if you only look at chemical and physical properties, you cannot distinguish between a primary and a secondary relationship; they can both be pretty strong. So a partisan of Sc-Y-Lu can note that a lot of properties fit, and say that when Sc-Y-La fits it is just an extra relationship; and a partisan of Sc-Y-La can note that a lot of properties fit, and say that Sc-Y-Lu only fits because of the lanthanide contraction. In order to decide, I consider it necessary to do what Jensen pointed out in 2017, and look at the fundamental property of electronic cloud structure. He even outright mentions "the necessity of looking not only at ground-state configurations but at available low-lying empty orbitals as well", which is very much resonant with what DA and I have been saying. The only problem is that that argument only works if you accept the bases above. I surely do, and consider these bases to be clearly important because they reflect the valence structure that controls chemistry. But if you don't agree that that's the most important thing, then this is hardly going to convince. In which case the whole thing keeps going.
 * Now I finally explain the s block. Calcium has some kind of d involvement and isn't a true-blue 100% homologue of magnesium, but zinc also has some kind of d involvement. So there is no primary relationship and we pick the secondary one (Ca) over the tertiary one (Zn). The weird smoothness of the group 1 and 2 trends makes sense under this paradigm because they are actually partly secondary-relationship trends: they match things like B-Al-Sc-Y-La-Ac and C-Si-Ti-Zr-Ce-Th which are analogous to Be-Mg-Ca-Sr-Ba-Ra and Li-Na-K-Rb-Cs-Fr. But there isn't a true analogy of any possible group 1 or 2 trend to B-Al-Ga-In-Tl-Nh and C-Si-Ge-Sn-Pb-Fl, so we pick these secondary relationship trends because there is nothing better.
 * Similarly, the same thing happens for the superheavy elements: the standard relationships stop working because of early drowning of 7s and 7p1/2. But, the result is close enough. Oganesson still has 7s2 7p6 outside even if 7s is not really contributing and neither is 7p1/2. In some sense it is like helium over beryllium: in both cases we have s2, but the meaning of that s2 changes. As the whole idea of the np-to-(n+1)s energy gap is based on the non-relativistic part of the periodic table, it seems OK to me to treat the late relativistic corrections as a perturbation of the basic structure. So we can idealise the s subshells as still being there even if they really are not. This is however still not quite a secondary relationship, because the valence electron counts don't match; rather it's more of a pseudo-primary relationship (what would have been a primary relationship if relativity hadn't spoiled it).
 * My preferred group numberings attempt to echo the secondary relationships: so for me, B-Al-Ga-In-Tl-Nh are group IIIp, which are clearly related to Sc-Y-Lu-Lr as group IIId and La-Ac as group IIIf. (Element 121 would start a group IIIg.) The s block groups, having no real partners, are relegated as Is and IIs.
 * So, to summarise: for me, this is not a matter of context; all these relationships are valid in every context as long as the elements stay themselves (i.e. keep the general electronic cloud structure); and we can clearly distinguish primary, secondary, tertiary, and quaternary relationships in terms of how good the analogy of the electronic cloud structure is. This may be displayed either implicitly (teaching the idea "same distance from a noble gas or pseudo-noble gas" to avoid drawing); through extra parenthesised symbols as in DA's version above; or perhaps through something like the Bayley-pyramid arrangement. However, the electronic structures and hence the periods and groups come first, and those follow the primary relationships whenever they exist, and secondary relationships whenever the primaries don't exist. So I still promote the idea of exactly one true nature of the elements that is displayed by He-Be + Sc-Y-Lu and by no other rectangular grid form, and the idea that Lu (say) is intrinsically a d block element and that it is a mistake to put it down as f block, but that does not mean I have anything against using and bearing in mind things like Sc-Y-La or B-Al-Sc as secondary relationships cutting across blocks (as all secondary and tertiary relationships do). Indeed, I advocate remembering every one of those relationships, primary, secondary, tertiary, or quaternary, in every single context. Not "this is more useful in one context, that is more useful in another"; for me, they all should be kept in mind all the time, as long as we remember whether they are primary, secondary, tertiary, or quaternary.
 * Of course, you may have a different view about these things. ^_^ Double sharp (talk) 10:34, 4 October 2020 (UTC)
 * Totally agree with Double sharp. Droog Andrey (talk) 20:55, 5 October 2020 (UTC)
 * Thank you!!! Double sharp (talk) 21:18, 5 October 2020 (UTC)

A thing of beauty
I think the pt above is a thing of beauty. It illustrates the secondary relationships in a much more economical and self-explanatory way than 's group resonances. It is if you will resonances of elements rather than of groups. I think what it expresses is identical or nearly so. It just requires less hand-waving to explain and less head-scratching to understand.
 * Thank you for creating this pt and for bringing it to my attention. Though I am not yet prepared to give up our enwiki metalicity categories, this pt has knocked me off the fence, landing me solidly in the garden of Sc/Y/Lu/Lr.
 * --- preceding unsigned comments posted by User:YBG 04:21, 6 October 2020‎ YBG
 * Thank you for signing for me! Much obliged! I think my failure to sign may have thwarted the pings. YBG (talk) 04:35, 6 October 2020 (UTC)
 * Thank you for your kind words. ^_^ Double sharp (talk) 20:26, 6 October 2020 (UTC)

Or is it?

 * Droog Andrey's table does not address nor resolve the group 3 question. His (incomplete) table is more conveniently displayed in 18-column form. As far as the 32-column table is concerned, Nature does not care about human conceptions of beauty. I discuss this in my article. Sandbh (talk) 05:57, 6 October 2020 (UTC)
 * It does fully address and resolve the group 3 question according to its bases, which you're of course free to disagree with. OK, it doesn't have the group numbers explicitly there, but I can add them:


 * So we can clearly see what it's saying. It says group 3 (the d block one, now called IIId) is Sc-Y-Lu-Lr, but that these elements have a secondary relationship (indicated by the parentheses) to B and Al in group 13 (IIIp), and also to La and Ac in group IIIf. That's a clear statement and resolution based on what was set out above regarding what we consider the fundamental properties of the elements. Of course, whether or not it convinces you depends on whether or not you agree with our bases, but it clearly makes a call.
 * I feel that this is much better shown in 32 column format. This way we can see exactly what's going on: you get a secondary relationship when two elements are the same distance away from a noble gas to the left, but not in the same group. (For a tertiary relationship, replace "left" with "right".) In other words, secondarily related elements have equal numbers of valence electrons, and tertiarily related ones – valence vacancies. So, you can naturally see it as what happens if you try to draw the elements "in the wrong places" by ignoring the gaps. This, I feel, is lost in the 18 column format. Oh, for sure you can display it in something like Bayley's pyramid arrangement too, but the point stands; cutting out the f block elements doesn't help. In fact it makes it harder to see what's going on because of the visual break IMHO.
 * Some of Sandbh's resonances are not shown in our table because they are neither secondary (isodonor) or tertiary (isoacceptor) relationships, but quaternary relationships. This is so of H-B, H-C, as well as Sc-Y-Gd. This is because there are really many such relationships (Al-Fe is another one, the diagonal relationships are also others), and the fact that these are rarely very strong because there usually is no matching oxidation state. In fact, I think Al-Fe (which he doesn't show) is actually stronger than H-B and H-C precisely because there is an oxidation state match: Al3+ and Fe3+. Whereas, good luck in finding any oxidation state matches for H-B and H-C.
 * Incidentally, I don't feel that Sc-Y-Gd is actually a very strong relationship either. Yes, it's true that the 4f electrons are somewhat sluggish and reluctant to participate in chemistry (though it is possible), but this is exactly why the Sc-Y-* table exists: every lanthanide looks fairly good under Y. No one can complain with La as a higher homologue of Y if it were the only lanthanide. No one could complain with Lu as a higher homologue of Y if it were the only lanthanide either. Or if it was Gd. Or if it was Ho. Or if it was Pm. (Exceptions being the ones with the +4 state.) So that's why La-Lu are sometimes taken in one space. Of course for Ac-Lr it becomes somewhat nonsensical, but again: a secondary relationship need not be universally strong (Mo-Nd is extremely weak, but Mo-U is strong).
 * It's not a matter of beauty: I didn't start with this beautiful form and seek to justify it. You may recall that my case for Sc-Y-Lu has nothing to do with symmetry but has everything to do with the presence of valence 4f involvement at La and its total absence at Lu. If hypothetically it were true that La had no significant valence 4f involvement but Lu did, I would be arguing with equal fervour for Sc-Y-La. But that's not the case, so I don't. So it's not a matter of symmetry for symmetry's sake, only symmetry because the data as I read it supports it. If I were going for a beautiful form first and foremost, I'd run to the Janet table, where every row beautifully has a partner and there are no gaps whatsoever. But I don't because it doesn't make any chemical sense: there's no mixing between (n−1)p and ns subshells (at least, not until relativity runs amok in a few bits of the seventh and eighth rows; using those as a justification is letting the tail wag the dog). As long as you accept our premises, you get our conclusion. If you don't, then of course it won't decide anything.
 * All this is of course my view, and you are of course free to disagree with it. Double sharp (talk) 10:35, 6 October 2020 (UTC)

I don't follow how the group 3 issue is resolved according to its bases, as you wrote, presuming you're referring to DA's table alone (as I did).

I can see the secondary and tertiary relationships, and related elements having equal numbers of valence electrons, and tertiary related ones – valence vacancies, just as well on the 18-column form. And I don't need to scroll off the screen. In any event, I recall Droog Andrey(?) saying something like the relationships he showed were not the only ones.

I'd forgotten about Al and Fe. That's a good one, thank you, and I've added it. Among other reasons, H over C works due to both elements having half-filled valence sub-shells. H over B works on account of the twenty or so relationships I set out previously. Valence considerations are not the only things to be considered in resonance examples. H over B and C were both recognised by Imyanitov (2016). There is much more to resonance than oxidation states.

Gd was recognised as the central metal of the lanthanides by Laing (2009), hence the Sc-Y-Gd- relationship.

The reference to beauty was raised by YBG: "I think the pt above is a thing of beauty." I took this to have partly contributed to him falling off the fence! Sandbh (talk) 05:56, 7 October 2020 (UTC)
 * Well, I explained it above, but sure, I can do it again. The basis of DA's table is that elements are defined by two attributes: (1) their atomic number, and (2) the structure of their electronic cloud.
 * We don't consider the differentiating electron for a couple of reasons. First of all, in the first place electrons are not distinguishable. It doesn't really make sense to pin down "an s electron" or "a p electron" when there is literally no way to distinguish between any two electrons. Please, see the article Identical particles. The electrons all have the same properties and we can't distinguish them by location, because we only have wavefunctions saying where they're likely to be, and these will overlap.
 * Secondly, an atom of scandium is not differentiated from an atom of calcium by its extra 21st electron alone, but also by its extra 21st proton. That's important because the increased nuclear charge of the atom has an impact on the energy of orbitals. If we look at the 20-electron isoelectronic sequence, we see Ca0 with configuration [Ar]4s2, but Sc+ with configuration [Ar]3d14s1, and then Ti2+ with configuration [Ar]3d2. What is happening is that 4s and 3d are very close in energy, and minor effects can shift the balance. The "competition" between 3d and 4s states is not a matter of 3d only becoming active at scandium; they're really both active already at potassium. It is actually because there are two opposing effects: (1) the 3d orbitals have a similar radius to the 3p ones in the core, and so there is a strong interelectronic repulsion that raises their energy, but (2) the 4s orbitals have some amplitude near the nucleus and feel its attraction more. The need to balance interelectronic repulsion is, as Richard Feynman points out in his lectures, the reason why the Madelung anomalies occur. But he is also quick to point out that the precise configuration actually can be impacted by the surrounding chemical environment:

In copper an electron is robbed from the 4s shell, finally completing the 3d shell. The energy of the 10, 1 combination is, however, so close to the 9, 2 configuration for copper that just the presence of another atom nearby can shift the balance. For this reason the two last electrons of copper are nearly equivalent, and copper can have a valence of either 1 or 2. (It sometimes acts as though its electrons were in the 9, 2 combination.) Similar things happen at other places and account for the fact that other metals, such as iron, combine chemically with either of two valences.
 * As a minor example of this: remember when I said Ti2+ is [Ar]3d2? That's true when it's alone, but in TiO it's closer to [Ar]3d14s1!
 * If we increase the charge, the nuclear attraction wins, and all the Madelung anomalies go away. Sc2+ to Zn2+ are consistently [Ar]3d1–10. And this is more or less what happens in a chemical environment; outside strongly ionic compounds, a metallic element due to charge-transfer will not have its "theoretical" oxidation state, but some fractional charge between 1 and 2 (for example, VCl4 has formal V(IV) but is closer to V2+). This sort of ligand-to-metal charge-transfer is not an unusual thing. It is absolutely common in the entire periodic table.
 * Further information about this, including the above example can be found in C. Jørgensen's article The Loose Connection between Electron Configuration and the Chemical Behavior of the Heavy Elements (Transuranics). Here he gives the f elements too as examples. Here, because 4f is close to the nucleus and in a region of even higher electronic density, the effect is even larger, and at low charges we cannot avoid occupancy of 5d (which is in a region of slightly less electronic density). But the effect as above still happens: La0 has [Xe]4f16s2 almost 2 eV above the ground state (which is still well within reach of chemical effects), but with La2+, [Xe]4f1 is only about 1 eV above. For cerium it passes zero; Ce0 [Xe]4f15d16s2 ionises to Ce2+ [Xe]4f2. The issue for lanthanum is not that 4f isn't participating in chemistry; it's just that, in the very special situation when a La atom is alone with nobody else around, over a xenon core, with this not-so-high nuclear charge, putting an electron in 5d rather than 4f lowers interelectronic repulsion. If other atoms are around, then 4f may very well be partially occupied, as we showed in the previous megathread with citations. It's the exact same story with Gd because of the stability of f7: f7d1 leads to less repulsion than f8 (the latter completing the first spin-pair). Notably this shows that it's really Eu that is the homologue of Mn. Just like Cr as an atom attempts to mimic the half-filled d5 configuration to lower interelectronic repulsion, Gd is mimicking f7 to do the same. The 5d1 occupancy at the beginning, like the 6d1 and 6d2 even at the beginning of the actinide series, is not a reflexion of a filling process where 5d fills and hangs up before 4f; it is rather that 4f and 5d are now both chemically active, but interelectronic repulsion results in an early filling of 5d just as it did for 6s!
 * As such, I consider it as clearly demonstrated that looking only at ground-state electronic configurations and differentiating electrons is not a sound basis. Reliable sources clearly understand this.
 * BTW, the fact that it's so well-known that ground-state electron configurations for the d and f elements are problematic is part of why I lost my cool and got frustrated with you in the previous megathread. I am sorry for it, but I still counsel: please, this information is so standard it even made the Feynman lectures on physics. Please, I counsel you, please give up on ground-state electron configurations and differentiating electrons. It will not do you any good. Please.
 * Well, let's go on. Despite these words against the exact ground-state electronic configurations and differentiating electrons, it remains that electronic structure is the mother of chemical properties. Some sort of understanding of electronic structure is needed to explain why the periods are the lengths they are. True, there are many effects; we can't for instance derive oxidation states from electronic configuration, especially all the more so because oxidation state stability is so strongly dependent on the ligands and charge (compare XeF8 vs XeO4, or TlI3 vs TlI4&minus;). But it all comes from there because the outer electrons are participating. That's why we have been saying; let's focus on the orbitals that can be involved in chemical reactions and their occupancy.
 * Done like that, the group 3 situation is immediately resolved 100% in favour of Sc-Y-Lu. Because we have the following situation:


 * The situation is clear. Scandium and yttrium use s, p, and d subshells for their chemistry. Lutetium and lawrencium are the same and act as true higher homologues; they match everything except for the principal quantum numbers of the subshells involved. They have a primary relationship, all four being (dsp)3, and therefore immediately go in the same group. But lanthanum and actinium are not the same; they also use their f subshells. These elements are rather (fdsp)3. True, they have a secondary relationship to Sc and Y, because they do still have three valence electrons, outside a noble gas core either. That is why trends going down Sc-Y-La, as well as Sc-Y-Lu, both look fairly convincing. And these trends are both valid, not only in their own contexts, but in any context. In all contexts, the relationship of yttrium to lutetium is important, and the relationship of yttrium to lanthanum is also important. But from the fundamental perspective of the electronic structure that is the genotype of the elements, Y-Lu must be admitted as the primary relationship.
 * Finally we can see the analogy. Boron and aluminium are (sp)3. Their true primary relationship is of course to gallium and its heavier congeners, which are also (sp)3. But they also have a relationship indeed to Sc and Y which are (dsp)3, and also to La and Ac which are (fdsp)3; all of B-Al-Sc-Y-La-Ac are three electrons over a noble gas, and for that reason they have some similarities. That's not a problem considering that the path from electronic structure to chemical behaviour is full of twists and turns. But we should understand that it's electronic structure that gives us our periodic table, not the matching of chemical properties, as should be clear from the placement of nitrogen and bismuth in one and the same group which are as different as chalk and cheese.
 * When element 121 is discovered, it will have three valence electrons with participating orbitals 5g, 6f, 7d, 8s, and 8p, and it will therefore immediately start a group IIIg. And this region of the table is the last death knell for ground-state gas-phase electron configurations: many superactinides don't even have a single such configuration, because too many configurations are too close to each other.
 * To summarise; under our paradigm, Sc-Y-Lu is fixed extremely simply by exactly one argument: the presence of significant 4f involvement on lanthanum, and its total absence from lutetium. Group 3 is resolved as Sc-Y-Lu. The duplication of parenthesised (Sc) and (Y) symbols over La, without any block colour, simply means that these elements have a secondary relationship to La that should not be forgotten. But it does not mean that La is a member of group 3. It still is not.
 * I know it's difficult to let go of Sc-Y-La; I know it's common; I know it's also difficult because you just got an article published supporting it. I really understand; remember, I worked with you on the 2017 IUPAC submission, I had a stake in the Sc-Y-La form as well. But, after some vacillation, I eventually let go of it. Sc-Y-La just doesn't reflect the fundamental properties of the elements very well and confuses the issue. The basis of the periodic table is not the final chemical properties (if not, N and Bi would never have gotten into the same group – not to mention N and Mc, since Mc shouldn't even have the +5 oxidation state), but fundamental properties that help to rationalise those things in the end. (And even if it was about the final chemical properties, there is not a difference between groups 3 and 4 that is not equally apparent between groups 13 and 14.) I discarded it quite reluctantly, but I did it in the end.
 * I'd like to just add that what convinced you to Sc-Y-La in the first place (previously you were favouring Sc-Y-Lu) was something I said in 2016 when I knew less on my talk page. Now I've learnt more, and I counsel; actually, I don't think it works anymore. I would be glad to explain to you again why I think it doesn't work anymore. But, please, listen to me. I do not like to see you using things that have been superseded in the literature. I know you want to know more about periodicity. Please, don't take this all as too complicated. Please understand: the point of science, as Feynman noted, is "understanding basic phenomena in terms of the smallest set of principles". It's not about how deep we're drilling down; indeed we are expected to drill down very deeply to do it. That's the basis of reductionism. It's about how much understanding we get from just a little. Sc-Y-Lu can help. I know I and Droog Andrey have been harsh, but at least for me, it's partly because I cannot bear to see you continue with misunderstandings and using simplest sufficient complexity, not in how it was intended to be used (Occam's razor), but to stay with something that has already been refuted.
 * I feel the 18-column form is not better, because cutting out the f block rather makes it more difficult to see the point: elements that are secondarily or tertiarily related to each other are the same distance from a noble gas, skipping the blanks. So you can find some secondary relationships by drawing the elements again in a way that ignores the gaps. This neatly rationalises the f block relationships in a way that I feel becomes significantly less obvious if we cut out the f block (so that the fifth period no longer neatly seems to go Rb-Sr-(Y)-(Zr)-(Nb)-(Mo)-... and then -(Sr)-Y-Zr-Nb-Mo-Tc again). Incidentally, it seems to me that whether or not we have to scroll off the screen is not so much a matter of Nature as it is a matter of aesthetics and technical limitations. ^_^
 * There is indeed more to it than oxidation states (otherwise the diagonal relationships wouldn't mean anything), but it seems to me necessary to have some sort of oxidation state match if you're going to have a relationship that's strong in any way. You may recall that I strongly criticised your approach towards H over B there as a bunch of disconnected facts. While I think my tone was a bit too harsh, I still agree with my sentiment.

It is, in fact, very simple to decide what observations are to be regarded as trivia. How connected are they with everything else in chemistry? And can such arguments be produced for almost any combination of elements? The latter would be a strong argument to consider an observation trivial. You "make an observation and proceed from there to see if other observations, including those made in the literature, are supportive". But do you look for the avalanche of other observations that are not supportive? I add the Wason selection task with its picture straight from its article as an illustration and a question. ... Double sharp (talk) 07:54, 14 June 2020 (UTC)
 * That's the standard I counsel that you hold yourself to. Please, don't just look for things supporting what you like. In order to truly prove something, you need to try to knock it down. By all means, formulate hypotheses to your heart's content. But then pretend you're neutral about it. And ask yourself: "OK, pretending that I don't know the answer like I didn't a few months ago, would this convince me? And what would convince me that this isn't right?"
 * I close with a quote from Sengcan:

If you want the truth to stand clear before you, never be for or against. The struggle between 'for' and 'against' is the mind's worst disease.
 * Yes, we all have our preferences. But when searching for truth, we have to try to pretend they're not there.
 * Maybe YBG thinks DA's form is beautiful. But he said something that in my view is more important. He said "It illustrates the secondary relationships in a much more economical and self-explanatory way than Sandbh's group resonances. It is if you will resonances of elements rather than of groups. I think what it expresses is identical or nearly so. It just requires less hand-waving to explain and less head-scratching to understand."
 * That's what I think science should be here for: explaining the most with the least. That's simplest sufficient complexity as it was always intended to be. Explanatory power is beauty. Double sharp (talk) 10:46, 7 October 2020 (UTC)

I understand all of this. As you have explained it to me, it is not DA's periodic table per se that provides the basis for Sc-Y-Lu-Lr, it is (1) atomic number, and (2) the structure of the electronic cloud. Do I have that right? Sandbh (talk) 05:59, 8 October 2020 (UTC)
 * Yes, that's correct. DA's periodic table is just also based on those two. Double sharp (talk) 08:22, 8 October 2020 (UTC)

Resonances not recognised
I didn't recognise C-Si over Ti as a resonance. That was a judgement call. G&E mention the relationship between group 4 and group 14 very briefly. There is not much to it. Siekierski & Burgess (2002, p. 104) write, "In fact, except for the maximum oxidation state +4, the Group 4 elements have little in common with the group 14 elements, even with the three heaviest (Ge, Sn, Pb)."

I ignored DIM's 8-column table as I was concerned only with the 18-column form. I have read criticism of much of DIM's mixing of the A and B groups as being largely shallow. But that may be a Western bias. I do however recognise the n, n+10 relationships seen in the 18-column form.

It seems to me that whatever the resonance, some forms do a better job showing the periodicity of some properties than other forms. That applies regardless of the basis for choosing the form in the first place (which should always be set out up front). That was what I tried to emphasise in my article. Sandbh (talk) 00:58, 6 October 2020 (UTC)
 * On the contrary, there is quite more than that, as expressed in Rayner-Canham's article. TiCl4 and SnCl4 are both tetrahedral and hydrolyse in water (that's also true of all the group 14 tetrachlorides), but more than that have very similar melting and boiling points. TiO2 and SnO2 are isostructural, and reversibly change colour on heating. More than that, but vanadium also shows significant similarities with phosphorus. And in fact, DIM's 8-column table with the A and B groups in the same columns works precisely because of the n, n+10 relationships. And these similarities seem to me to be way stronger than whatever similarities can be found for hydrogen to carbon; at least these actually share a common oxidation state. As we know, stoichiometry is extremely important in chemistry: that's why Mendeleev's table had the formulae for hydrides and oxides listed (R2O, RO, R2O3, etc.).
 * All the periodicities always exist, and as shown above it seems to me perfectly possible to create a table that shows all the ones with chemical significance, while stressing exactly how they arise. (Of course something like the lack of Zn-Cd-Dy being shown doesn't bother me; yes, technically, formally it is a valid secondary, but it has zero chemical meaning.) As you know, I do not feel that there is a need to set out the bases universally because it seems to me that electronic structure, being as fundamental as it is, is a good enough basis for pretty much every normal use case. Let me repeat for clarity: I don't consider the situation to be "in some cases one resonance is more important and in other cases another is more important". I consider the situation to be "in all cases all resonances are important and should be understood". For me it's not "sometimes Sc-Y-La is better and should be shown, sometimes Sc-Y-Lu is better and should be shown"; it's "Sc-Y-La and Sc-Y-Lu are both always important and should be understood, but it should also be understood that the first is secondary and the second is primary". That's why I favour either explaining how to get secondary and tertiary relationships (count equal columns ignoring f and/or d block gaps from the edges of the table), or using parentheses to explicitly show the most important ones.
 * In fact, I actually think that overemphasising one resonance at the expense of others can be quite harmful. I would consider that a form with explicit Sc-Y-La actually does a worse job at showing the resonance Sc-Y-La than a strict Sc-Y-Lu or the one above, because it gives the implication that Sc-Y-La is a direct, primary relationship, that there is no significant 4f involvement in La, that there is a markedly stronger 5f involvement in Th, and that Sc-Y-La is a significantly stronger resonance than B-Al-Sc because the latter isn't shown. I think the data is against all of these statements. And I think the absence of La from at least one study of 4f involvement in the lanthanides (here it is) may be a bad consequence of the common Sc-Y-La form; because La visually appears to be before the 4f series, that may contribute to people not investigating its 4f involvement precisely because they think there's no point and that it can't have any. (Yes, the same problem would impact Lu if Sc-Y-Lu were the common one, but at least then it's actually correct that Lu doesn't have any significant 4f involvement, and we know it because it's been investigated in that paper; if even hyper-electronegative and small fluorine and oxygen cannot coax it out, like can happen for Zn 3d, then it's just not going to happen.) But you may disagree. Double sharp (talk) 10:35, 6 October 2020 (UTC)

Thank you. Yes, I now recognise the C-Si over Ti relationship. H over C (or B) I've addressed above. Yes, I agree with you. Overemphasising one resonance at the expense of others is unhelpful. They all have validity within the applicable context. I said previously that electron structure is fine for its context and that, as with all attributes of interest, it shows some aspects of periodicity no better or worse than others. As noted in my article it is ironic that, akin to a game of whack-a-mole, attempts to improve regularity in the appearance of the periodic table increases the number of irregularities amongst various other properties and relationships across the table, and cognitive dissonance with respect to chemical relationships between or within groups or series of elements. Like Plato's cave, no form of PT is capable of capturing all aspects of periodicity.
 * Please, see my response in the previous section. Double sharp (talk) 10:48, 7 October 2020 (UTC)

A "radical" eight-colour scheme


This proposal is based on the following premises:


 * 1) Scerri's contention that, “The periodic table has now become as much the property of physicists, geologists, astronomers and others as it is of its chemical originators.” (2020b, p. 7).
 * 2) Our periodic table article is an article about the periodic table rather than a strictly chemistry-based periodic table.
 * 3) In this context, the AE and AEM are not worth separate colour categories, for the literature-based reasons set out previously.
 * 4) The Ln and An can be marked as such, rather than needing separate colours.
 * 5) YBG's preference for fewer categories per 7±2
 * 6) The most common names found across the literature for each category.

Premise #2 is the most important premise. Not observing it has been the cause of all our difficulties. IUPAC does not own the periodic table.

The radical proposal has four metal categories; one metalloid; and three nonmetal. Given metalloids have a predominately non-metallic chemistry, this results in four metallic and four non-metallic categories. Speaking boldly, as I see it, it appears to be the first table to solve all issues raised in past discussions. Note the treatment of Al (per Deming), Th, Lu and Lr.

Whatever you believe is missing or should be removed can be added to the categories section of our periodic table article.

It was liberating to throw off the IUPAC shackles and to apply more of a cross-disciplinary perspective rather than being unduly concerned about what a chemist would think. Chemists don't own the periodic table.

Could you please let me know how it looks. Sandbh (talk) 11:19, 6 October 2020 (UTC)
 * In fact, I don't like it; my apologies for that. Whatever reason there may be for it, it remains that AM and AEM are way more common than "pre-transition metal". And of course, there's no way to appeal to all groups simultaneously. I suspect that astronomers are going to be much more interested in how the elements were made (BBN, stellar nucleosynthesis, s process, r process, p process, decay chains, synthetic) than their actual properties. And as I said above, although one may argue about how chemists shouldn't own the periodic table, the fact of the matter is that they are de facto its custodians, with some joint ownership from physicists. Which organisation makes statements about categories? IUPAC. Which organisation is deliberating the group 3 issue? IUPAC. Which organisations evaluate discovery claims for new elements? IUPAC and IUPAP – and there are complaints that IUPAC dominates the process too much, because this is more physics than chemistry and has been ever since nobelium and lawrencium were discovered, but chemists cling to the process! So we should, IMHO, continue to be concerned about what chemists would think.
 * I continue to prefer either V5a with "other nonmetals" instead of "light nonmetals", or no change from status quo. That's also a compromise on my part: my secret inner preference is what I show at User:Double sharp/Periodic Table (only blocks + metal/nonmetal; of course, those group numbers need some outside appearance first). It seems to me that V5a with "other nonmetals" has a chance of getting a consensus: things near the edges (throwing out categories or throwing out IUPAC) seem unlikely to get a following, but something near the middle probably has more of a fighting chance. So, whatever we really want deep down, I suggest we stick to a compromise that everyone at least can agree is an improvement over the status quo, rather than try to change a lot at once and end up in a situation where everyone wants a change, but no one can agree on what the change should be to, and so nothing happens. Double sharp (talk) 11:27, 6 October 2020 (UTC)

Thank you; no need for apologies ^_^ All part of the discussion process.

Please correct me if I am misguided: our periodic table article is about the periodic table in general, across all disciplines. It is not the periodic table (chemistry). If the latter was the case, then sure, AM and AEM stay. Even then, the chemistry literature recognises the difference between the two categories is more of degree than kind; and that the chemistries of the two categories resemble one another to a large degree!

Appealing to all groups simultaneously is not required. I suggest we are obliged to, in the best encyclopedic tradition, give due consideration across disciplines, rather than paying undue heed to chemistry, chemists, and IUPAC.

IUPAC relevance is limited and mixed. Yes, with IUPAP, they recognise and approve names for new elements.

While IUPAC also approve names of sets including (a) AE: (b) AEM; (c) lanthanoids; (d) actinoids; and (e) rare earth metals, items (c) and (d) are widely ignored in favour of lanthanides/actinides; and "REE" is more common than REM. IUPAC further incorrectly note groups 3−11(12) are commonly referred to as "transition elements" whereas the elements involved are actually way more commonly referred to as transition metals. Even Jensen, a chemist, off-handedly disparaged IUPAC:
 * "As scientists we should base our conclusions on a critical examination of the chemical and physical evidence and not on an appeal to authority or the arbitrary whims of committees and popularity polls. Above all, such demands should be tempered by the sobering recollection that IUPAC is the organization that brought us density in units of kg/m3, 4πε0 in the denominator of Coulomb’s law, and the finger-count labels 1–18 in the periodic table."

Not forgetting IUPAC are of no help with regard to nomenclature for the so-called post-transition metals; metalloids (repeatedly criticised by them, with their confusing suggestion to use "semimetals" instead never mind the mix-up with the physics-based sense) and the orphan nonmetals.

I contend the views of the metallurgists and representatives of the 19 other fields of study I mentioned in "notes on the other nonmetals", here, are as important as those of chemists.

I like V5a too. Houston, we have agreement. Yahoo!

I wouldn't've posted this radical proposal but for Scerri (chair of the IUPAC group 3 project, no less) writing that the PT has now become as much the property of physicists, geologists, astronomers and others as it is of its chemical originators.

I agree the way ahead in terms of introducing possible change requires careful consideration. I'm not there yet; I'm still in the background-information-gathering, discussion, and sounding-out stage. Sandbh (talk) 03:08, 7 October 2020 (UTC)
 * Except I am not convinced at all about how you interpret what Scerri says. As a statement that the PT is used also significantly by those other fields, surely I agree. But I don't agree that they have equal relevance when it comes to the categories used on the PT, and I don't see that in what he says. Exactly what are those other disciplines using the table for, if not to rationalise the chemical properties of the elements that are of interest to them? That's not so much another claim to the table, in my opinion, as it is. The fact of the matter is that IUPAC is the organisation making statements about the periodic table. Sure, they're not always listened to, but apart from a few things from IUPAP no one else is doing it. Is there something similar coming from geologists or astronomers? I rather doubt it but I'm ready to be convinced if you can show me such.
 * What Jensen says is completely, 100%, correct when it comes to the situation he's writing. It is, however, not correct for Wikipedia. The whole thing about WP:NOR is precisely about appealing to authority and popularity polls; you need to reflect the situation in the literature and not add something to it even if you feel the situation is completely inadequate. And that's exactly why, even though I agree with you that the difference between AM and AEM is not that significant (it's really just valence), I still oppose getting rid of them as categories. On WP, we're supposed to reflect the literature and not try to change it. That literature, as I see it, seems to be that chemists are de facto first among equals when it comes to deciding what the PT looks like, with physicists as a close second and everyone else far behind. Whatever you think about IUPAC (and I admit I'm not that impressed by them all the time either), it remains that we don't have much else that's better.
 * Anyway: I think V5a is good, except that I would prefer "other nonmetals" still for the above reasons. In fact, I would even prefer "other metals" because Post-transition metal shows that there's lots of names for this or a similar set of elements, none of which have any sort of official stamp, and none of them are really dominating in the literature. I think an "other" category better reflects that. And besides, I think having "other" categories is more or less forced on us by the simple fact that these categories were never really intended to become exhaustive and mutually exclusive in the first place; they were just invented to group similar elements together. It's not particularly surprising to me anymore that an element like hydrogen with such unique chemistry is very difficult to put in anything other than an "other" non-category. But to me, that's not like throwing it into a dustbin, but an acknowledgement that these elements are really special and don't fit well into categories grouping together similar things. But, since "post-transition metal" at least seems to have more currency in the chemistry-based literature than "light nonmetal", I won't insist on changing to "other metal" as well. Double sharp (talk) 11:24, 7 October 2020 (UTC)

I note:


 * IUPAC only "approves" collective names for like elements.
 * The use of these names is not mandated.
 * IUPAC has not approved a collective name for group 3 to 12!
 * As you note, and I suspect R8R might agree, the divide between the AM and AEM is more a divide for the convenience of having a divide, rather than a divide of major significance e.g. between blocks, or within the p-block, where all kinds of hell break out.
 * From the COPTIC database of 62 more recent chemistry textbooks, AM and AEM have only a 10% appearance frequency!
 * The higher level PT graphic is not the same as the detailed contents found in an actual chemistry textbook that would mostly include e.g. a group-by-group discussion of the TM or the light TM in period 4 and the heavy TMs in periods 5-6. Thus, why do we not separately colour-code each individual TM group or p-block group on our graphic? Because the great majority of chemistry text-book authors recognise the distinction between a higher-level graphic, and the main corpus of the book.
 * Deming, a chemist, and the guy who popularised the 18-column table, sensibly wrote that the AM, AEM, and Al were light metals. He retained the AM and AEM nomenclature, but gripped up the two sub-categories into the LM category. And in his chapter on the LM, after discussing their shared properties, he still allocated separate sections to the AM and AEM, and Al, since that is what a text book is for.
 * D thereafter distinguished between the transition heavy metals (groups 3-10); rare earth metals; and the heavy or post-transition metals (groups 11-16). In the rest of his book he had chapters on hydrogen; the halogens; the sulfur family (group 16; why the "sulfur" family?); nitrogen; carbon; and silicon and boron.
 * There is no basis in the literature, per the COPTIC database, to insist on the inclusion of the AM and AEM on our PT graphic (as opposed to any footnotes).


 * Per YBG, 4+4 is all we need in our graphic. Sandbh (talk) 07:30, 8 October 2020 (UTC)


 * Please please keep distincting "colours" and "categories". We can have 'category' talks, and 'color' talks separately. -DePiep (talk) 21:21, 7 October 2020 (UTC)

ACS Division of Inorganic Chemistry 32-column PT Logo
It seems they have revered to the La form, judging by recent e-mails I have received from them.

That is odd, since Eric had reported the logo was withdrawn due to the controversy associated with the Group 3 question. See note 15, here. Indeed I remember getting e-mails from the ACSDIC with a 32-column Lu logo. I remember thinking at the time that was an odd choice since it replaced one controversy with another.

I have no idea what's going on. Sandbh (talk) 03:23, 7 October 2020 (UTC)

If we really want the "Other" categories
My point here is that if we have "other" categories, those categories must come at the end of the list ... other metals at the end of the metals, and other nonmetals at the end of the nonmetals. Note that by this graphic I am not endorsing a particular scheme. my main point is simply that the "other" must clearly be at the end of the list.

This legend includes some things that I like and some that I abhor. A few additional notes --- YBG (talk) 07:37, 7 October 2020 (UTC)
 * 1) I prefer "Active metals" to "Light metals" for a number of reasons, but primarily because it makes more sense to me and because I'd prefer to exclude Aluminum..
 * 2) I prefer "Inner transition" because I think it is a well-known term and because by combining the Ln and Ac we reduce the number of categories. My only hesitation is that I don't know if the two series are chemically similar.
 * 3) I rather like PTM, but the point here is to illustrate how to incorporate "Other-X" category names. But it is nice to have two parallel "Other" categories, M and NM.
 * 4) I use "noble gas nonmetals" intentionally, so that it it is clear which categories are nonmetals and that metalloids are not nonmetals.
 * 5) I still dislike separating the reactive nonmetals, but it is nice to have four categories on each side.
 * 6) I dislike the term "halogen nonmetals" and I dislike subdividing the reactive nonmetals, but if you must have the split ...
 * 7) I dislike the "Other nonmetals" name, but I find it significantly better than "light nonmetals", which unfortunately excludes the 2nd lightest nonmetals (He) making the name seem misleading, and of course, there is the unfortunate issue of including Se which is sometimes called a heavy metal. Very puzzling for something to be categorized both as a heavy metal and as a light nonmetal.
 * 8) I am making no statement about color choice; I merely tried to stay as close to what we have as I could.
 * I find it a but disingenuous that I use terms like "prefer", "like" and "dislike" as it makes everything seem to be a matter of personal esthetic preference. Well, in many ways, that is what it is. And frankly, I prefer (!) prefer/dislike over other ways of expressing things given recent difficulties which have made the past few months sadly the most un-collaborative I have experienced in my years at WP:ELEM.
 * The main point of this post is simply that if we wish to restore "Other-X" categories, a legend scheme like this just might avoid the horrid sound of the "other-X" category names.
 * If we end up with more than eight categories, I have no idea how the legend could even approach being aesthetically pleasing.
 * I am fully aware that using a legend like this would wreak havoc with the legend options in our PT templates. Resolving that issue is by no means trivial, and I will say this: if we cannot figure out a way to present "Other-X" as last in the list of X's, then I would oppose the resurrection of those category names. For me, this is a non-negotiable, trumped only by my respect for consensus.


 * Let me answer briefly:
 * I still don't like "active metals". These are not the only active metals around; the early lanthanides are pretty reactive too. I'm against getting rid of AM and AEM here just because these names are way more common in the literature than any name for a combination of the two. And they are distinguished in one particular way; the valence (almost always +1 for AM and +2 for AEM).
 * The Ln and An are not that chemically similar (which is mostly the fault of the first half of the actinide series). On the other hand, the actinides are not even that chemically similar to each other in the first place (which is again the fault of the first half of the actinide series). Such a unified category would probably be OK because it would have about the same amount of internal diversity as the transition metals. The only problem is that "inner transition element" is defined by IUPAC as the f block and therefore I am hesitant to suggest it because it depends on the group 3 issue. Now, I know you, ComplexRational, and Droog Andrey are for a change back to Sc-Y-Lu, and so am I. Previously Dreigorich, when he was active here, also supported it, as did Officer781. But we have R8R and Sandbh who are against it. I know R8R prefers Lu himself and is only against it because he feels the literature doesn't justify it (which is a point of disagreement with me; I have a source list explaining why I feel it does), but Sandbh just published an article supporting La. Consensus doesn't require unanimity, but this isn't really one yet, and the feelings at WP:CHEM should probably also be considered. I have posted something about the group 3 issue above, so we can discuss it there. But because this is somewhat fraught, I would probably avoid suggesting Ln and An unification until a real consensus rather than an agreement to disagree arises here on group 3 (assuming it ever does).
 * I do like "other metals" for WP. I think, we have to admit from the list at Post-transition metal that there isn't really a single name for the elements in this category, so in my view we shouldn't create one. "Other" may be wringing our hands in despair, but at least it's justified despair. Same goes for "other nonmetals".
 * I like putting the "other" categories at the end of our list. It makes it very clear that they're the leftovers.
 * In fact, I think it's good to have "other" categories because it makes one thing pretty clear: these categories were never supposed to be exhaustive in the first place. They were not invented to fulfil your rules, but rather to lump together some sets of elements that are pretty similar to each other, with no worries about whether an element ends up in more than one category, or if some elements end up outside categories. (Hydrogen, having a very unique chemistry compared to everyone else, seems almost guaranteed to end up as a leftover, for example.) So to some extent, I think the fact that avoiding "other" keeps giving us awkward names that are not quite standard in the literature suggests that we have the wrong goal here. Double sharp (talk) 11:14, 7 October 2020 (UTC)


 * for 4+4. Could we not "flag" the AM and AEM per the radical proposal? Sandbh (talk) 06:31, 8 October 2020 (UTC)

Some passing comments, which will be buffeted by the outcome of other discussions:
 * “Pre-transition metals” is a crisp term for groups 1–2 and Al (noting the Be-Al diagonal relationship) and is found in the chemistry literature; see e.g. Inorganic chemistry by Cox (2004, p. 185).
 * “Poor metals” is ×12 times more common than post-transition metals.
 * ”Light metals” is ×14 times more common than poor metals.
 * There is no puzzle about Se. It’s sometimes classified as a heavy metal since its waterborne chemistry is similar in some respects to that of As and Sb. By its density it’s a light metalloid even though it’s more generally recognised as a nonmetal proper. It’s the usual fuzziness at the boundaries
 * Inner transition metals is fine; IUPAC only comments that the f-block elements are sometimes referred to as inner transition elements, that is all. Even then inner transition metals is more common.
 * Other categories are preferably avoided, IMO, as they result in a lack of considered study of the attributes shared by the elements in question, not to mention a multiplicity of category names. Sandbh (talk)

Regarding the latest additions to Periodic table
I have to admit that I am not too happy with User:Sandbh's additions on categories to the Periodic table article. I have not reverted anything, it is all still up there, but I would like to discuss it here.

(Forgot to link to what I was talking about: it's the section Periodic_table. Double sharp (talk) 20:53, 8 October 2020 (UTC))

The first complaint I have is that there is a great paucity of citations. That does not seem proper for an WP:FA.

The second one I have is that the text does not appear to be NPOV, but rather skews towards overemphasising things Sandbh seems to be personally in favour of, and underemphasising things he seems to be personally not in favour of.


 * The viewpoint Sandbh favours that the alkali and alkaline earth metals are not really that different from each other in kind, just in degree, is given prominence by collecting them as one section and explicitly saying it. Certainly, there is a citation – but is this really a representative one? Most books seem to treat the two categories rather separately. Pretty much every chemistry text that's organised by group like Greenwood & Earnshaw or Holleman & Wiberg would do so. There are many opinions in the literature, but is this one that is common enough to put into an introductory-level article like periodic table?
 * Sandbh calls out the noble metals as a separate category in themselves. Again, that's something he's proposed before. But that category has a fuzzy border and is not often used to explicitly divide the table up this way. Worse, he excludes Ag from the list of the metals that are generally included as noble metals, and writes a note saying "Silver is too reactive to be considered as a noble metal". Why? On the basis of one source (Rayner-Canham) that does so. The source says "This author would contend silver is so much more chemically reactive…that it should not be considered as a 'noble metal.'" So that's what one author thinks. Does that justify a bald statement "silver is too reactive to be considered as a noble metal" without any attribution, as if this was something generally agreed like "silver has atomic number 47"? Moreover, that says nothing about whether or not Ag is generally included. On the contrary, if you go to noble metal, you will see a cited statement (to Holleman & Wiberg, a standard German inorganic chemistry textbook) that Ag is among the metals generally included as noble. It would be a reasonable reflexion of the sources, IMHO, to say "Ru, Rh, Pd, Ag, Os, Ir, Pt, Au are generally considered noble metals, although concerns have been raised about Ag due to its greater chemical reactivity compared to the other seven". But to leap to the idea from one voice of dissent that Ag suddenly isn't generally included as a noble metal seems to not follow what the sources actually say.

Every one of these viewpoints given prominence, that I mention above, is one that Sandbh has made statements favouring. Other viewpoints are not listed. And to make things clear: I do not have a general automatic feud against whatever Sandbh says, and I even agree with the viewpoint he favours about the alkali metals and alkaline earth metals. This is about WP:UNDUE in my opinion.
 * The pnictogens and chalcogens are IUPAC-approved category names (names for sets of like elements); surely, as IUPAC is the International Union of Pure and Applied Chemistry, their statements are worth considering. See p. 51 of the 2005 Red Book. In fact, it seems to me that their statements are more worth considering than those of non-IUPAC-approved categories like "noble metals". Yet if you read the section on categories you would get no indication that "pnictogen" is a category name. You would only get, in a later section, the indication that it is a group name – which IUPAC does not say. So we currently have IUPAC-approved categories getting less weight than non-IUPAC-approved categories. Is this a fair reflexion of the status of IUPAC?
 * Sandbh writes "Lanthanum and actinium in group 3 are shown as a lanthanide and actinide respectively yet both are also transition metals", presupposing that La and Ac are in group 3 without any mention of the controversy. It is, as clearly stated in Periodic_table, not agreed in the literature whether La and Ac are in group 3, or Lu and Lr are. I think my work-in-progress list of sources speaks for itself. This could so easily be written around just by saying "The heavier members of group 3 are shown as a lanthanide and an actinide, yet both are also transition metals". But he doesn't do that. And, of course, Sandbh has been a strong advocate of the -La-Ac form here for months, and has recently published an article presenting arguments in support of it. Even if it's not his intention to be biased towards -La-Ac here (and I don't think it is), this sort of thing, combined with earlier not giving a note about group 3 on his preferred PT images until I stepped in and suggested it (while other notes about things he was interested in were present), makes me concerned.

(Added later: I understand that this is likely to be unintentional; we all have our own preferences, and no doubt they bleed out when we write when we don't think about it. But, still; I think we should do some more to curb them. Double sharp (talk) 23:11, 7 October 2020 (UTC) )

But the one I have most of a complaint with is the line just before the sections for the categories:

Scientists need not, "lose sleep over the hard cases as long as a classification system is beneficial to economy of description, to structuring knowledge and to our understanding, and hard cases constitute a small minority."

This is a quote he has often referred to in our discussions here. In that context it's perfectly fine. But exactly what is it doing in this article on the periodic table? It's cited, so let's look at the citation. It's not from a book about the categories of the periodic table. It's not even a book about the periodic table. It's not even a book about chemistry. It's a book about the dwarf planet Pluto! And here are the names of its chapters:


 * 1) The Solar System
 * 2) The discovery of Uranus, Neptune and Pluto
 * 3) Pluto: a diminishing world
 * 4) Pluto's family
 * 5) Surfaces, atmospheres and interiors of Pluto and Charon
 * 6) The Edgeworth-Kuiper belt
 * 7) Is Pluto a planet?
 * 8) The New Horizons mission to Pluto [and beyond]
 * 9) Pluto: gateway to beyond?

I admit, I haven't had time to read the whole book. I have things to do in RL and it's over two hundred pages. But these chapter titles don't give me any confidence that the book is generally relevant to chemistry at all, let alone the periodic table!

Exactly where does this quote come from? From p. 171, at the chapter "Is Pluto a planet", where classification in science in general is briefly discussed for a total of two pages (bottom of 169, 170, and most of 171). That's it. And in these two pages, the chemical elements as something to classify are not even mentioned once. The example given for the general discussion is crystals, which is at least semi-related to chemistry, but the relationship to categorising the elements into various categories is extremely strained if it's present at all. The rest of this chapter is about the classification of Pluto.

I don't see how this is relevant. How is the opinion of an astronomy professor on classification, expressed in a context that does not even mention the chemical elements, not WP:UNDUE when it is put on an article that describes classifying the chemical elements? I don't think it is. Maybe others may disagree with me on this, but I think my concerns are enough to justify the next step of the WP:BRD cycle: we go back to something we agree on, and discuss how to improve the version that has been boldly put up. (Added later: I'm willing to forgo the R part of the cycle in good faith, and go straight to discussion. Double sharp (talk) 23:11, 7 October 2020 (UTC) )

I have not edited anything in this section, and I'm reluctant to say this in the first place, but to me this in particular seems to be getting uncomfortably close to WP:SYNTH. I find this use of sources problematic, especially for an WP:FA.

So, in the spirit of WP:BRD, could we perhaps have this addition discussed, hopefully without drama, as it is not uncontroversial? Double sharp (talk) 19:18, 7 October 2020 (UTC)


 * I would appreciate your views on this matter as well to facilitate building a consensus. Double sharp (talk) 22:39, 7 October 2020 (UTC)
 * 1st: Great reading, thanks for spending time on this to get it clear. 2nd: later ;-) -DePiep (talk) 22:54, 7 October 2020 (UTC)
 * Thank you, and looking forward to your view of the matter. I added a few afterthoughts above in parentheses, incidentally. ^_^ Double sharp (talk) 23:12, 7 October 2020 (UTC)
 * Thanks for raising your concerns here rather than reverting. I like your style. I see you also gave me permission to revert one of your own edits at PT (which I haven't looked closely at yet). Nice! Sandbh (talk) 23:58, 7 October 2020 (UTC)

Sandbh comments

 * Preface
 * Speaking personally, I was taken aback by how I interpreted the tenor of this post, and the words "complaint"; NPOV; WP:UNDUE (×2); WP:SYNTH; and WP:BRD. I feel there are better, more collegial ways of saying these things within a project. I feel particularly slighted by the need to invoke so many WP policies.


 * That said, I intend to presume WP:GF and respond in a civil and collegiate fashion per the sentiment of your request rather than (as I personally saw it) the superficial and hopefully unintended connotations of the words involved.


 * Items of concern
 * As I see it, all of these are easily dealt with. All the following is IMO, and shared within our project as colleagues.


 * 1. A "great" paucity of citations. The content referred to is general knowledge. Citations are only required for "any material challenged or likely to be challenged", per WP:CITE. That is the case for any article, regardless of its classification, including WP:FACR In an event, anybody is welcome to add citations should they feel so inclined. When I posted the context in question it included ~10 citations. Wither great paucity?


 * 2. Lack of NPOV?


 * a. AM/AEM. Consistent with most books, we continue to show AM and AEM as separate categories, with their own colour categories. Contradict me if I am wrong but the similarities between the AE and AEM are plainly evident; ask any chemist. I included two non-controversial citations. I gave another eight citations related to the similarities of the AM and AEM, here. Regarding, "…is this one that is common enough to put into an introductory-level article like periodic table?" Since our article on the periodic table is not an "introductory-level" article, I don't understand what concern is being raised here. In any event, I don't know how much more introductory it could be to note the similarity between AM and AEM. Even their names are similar.


 * b. Noble metals No, I did not call "out the noble metals as a separate category in themselves." What did I write? Here it is:


 * "Among the transition metals, the noble metals (generally Ru, Rh, Pd, Os, Ir, Pt, and Au)[n 3] correspond to the noble gases.[37]"


 * Note that:
 * I didn't refer to the NG as a "separate category";
 * I used the qualifier "generally", cognisant of what we spoke about before;
 * I didn't "highlight" silver within what I said; rather, for interest, I added a footnote[n3] (our PT article has 21 such footnotes);
 * I provided an explicit supporting citation, Wiberg no less, regarding the equivalence of the noble metal and noble gas categories. Ask any chemist about this. I wiki-linked the reference to the noble metals, in the best WP tradition, so that anybody whose interest was piqued could follow up on that.


 * You rightly wrote, "But that [noble metal] category has a fuzzy border…". This fact has no relevance. Fuzzy borders are a general feature of classification science. At least the following of our categories have fuzzy borders: AEM (Be and Mg are not AE metals); TM; PTM; metalloids; and "other" nonmetals. I'll pick up this theme again when we get to the quote by Jones.


 * I do like your suggestion i.e: "Ru, Rh, Pd, Ag, Os, Ir, Pt, Au are generally considered noble metals, although concerns have been raised about Ag due to its greater chemical reactivity compared to the other seven". Perhaps we can regard Ag as the Rn of the noble metals.
 * Suggestion DONE. Sandbh (talk) 00:05, 9 October 2020 (UTC)


 * 3. Other viewpoints not listed
 * You wrote:
 * "Every one of these viewpoints given prominence, that I mention above, is one that Sandbh has made statements favouring. Other viewpoints are not listed."
 * That's because: 1. I read, I write (here or in the article space or for the literature), I cite; I refine; and 2. I seem to be the only one with a 10,000 hour interest in classification science matters as it relates to the periodic table. You've seen the work I did on tidying up the metalloid article, and related work on heavy metals; metal; nonmetal; post-transition metal; and my publications, submission, and articles in the literature. And to think all that started when I saw the edit war as to which elements were metalloids, nearly ten years ago.


 * 4. WP:UNDUE


 * a. Pnictogens. Double sharp is concerned that I mention noble metals in the categories section, but not e.g. chalcogens. The latter term is recognised by IUPAC; the former is not. My understanding is that our PT categories are based on metallicity, as YBG noted recently. In that context, I mentioned the noble metals noting they correspond to the noble gases, per Wiberg. Double sharp, you mention that there is no mention of chalcogen in the categories section? Why would we do so when the categories section is about WP categories, not IUPAC-approved collective names for like elements? For that matter why do we not mention the pnictogens and the rare-earth elements (even though REM is more popular in the literature)? Why do we refer to transition metals when the IUPAC-approved name is transition elements?


 * b. La-Ac in group 3. That is a good suggestion. Regarding, "This could so easily be written around just by saying 'The heavier members of group 3 are shown as a lanthanide and an actinide, yet both are also transition metals.' But he doesn't do that." I didn't do that because I'm not a mind reader nor did it occur to me at the time. That's all.


 * Suggestion DONE. Sandbh (talk) 00:05, 9 October 2020 (UTC)


 * 5. Most of a complaint re the quote by Jones/WP:SYNTH
 * The quote, which is from a reliable source (Cambridge University Press), deals with classification science. The context for the quote is the previous paragraph in the periodic table article…


 * "An individual category is not necessarily exclusive according to its name, boundary, or shared properties."


 * …followed by three examples.


 * Thus, while there might appear to be some flaws in the category names (themselves derived from IUPAC-approved collective names) such as AEM, there is no real drama in classification science terms.


 * Similar themes, re atypical properties at the boundaries and boundary overlaps are explored in the Linking and bridging groups section; in the lede of the metal article where differing conceptions of what a metal is in physics, chemistry, and astrophysics are discussed; and in the metalloid, post-transition metal, and nonmetal articles. (WP:COI declaration: I've edited all these articles.) We have discussed blurry boundaries within our project for many years wrt to e.g. the other metals, metalloids, and other nonmetals. Similar discussions can be found in the literature concerning e.g. whether or not groups 3 and 12 are TM groups; and the location of the metal-nonmetal dividing line.


 * Here's a related quote concerning the importance of classification in science generally noting that, from the last I heard, chemistry is regarded as the central science:


 * “At any given time, during the historical development of a scientific discipline, classification of available evidence offers itself as the explanandum that asks for a theory (or alternative theories) able to explain it. But this is just one segment in a potentially unending chain of recursive relationships between classification and theory. Theory and classification indeed change over time. As a consequence, the theory that provides explanation for the data organized in a classification at a given time can influence subsequent classificatory effort, and so on. “By means of this a discipline advances: each new pattern raises questions that call for explanations, and each verified phenomenon or fact gives a new pattern” (p. 163). What counts as a fact or a theory is a matter of temporal relativity. The authors’ “concern is that we do not replace observation with theory and think that we have made some progress. Science is founded upon empirical observations, no matter how these are tied up with local and cross-disciplinary theoretical commitments or stances. Once we abandon this aspect of science…science becomes little more than a matter of worldviews and epistemic statements of faith” (p. 163).”
 * -- Minelli, A.: The nature of classification: Relationships and kinds in the natural sciences—By John S. Wilkins and Malte C. Ebach. Systematic Biology. 63 (5), pp. 844–846


 * The general discussion of classification science occurred in a science-based book, written by an Emeritus Professor, with a PhD in experimental solid-state physics, in a Department of Physics and Astronomy. While he was addressing the controversy surrounding the classification of Pluto, the principles of classification science involved are universal.


 * I remain genuinely puzzled as to the nature of your WP:SYNTH concern. Since when did we seek to quarantine and hide knowledge? A great encyclopedia illuminates the cross-disciplinary nature of scientific knowledge (as well as other kinds of knowledge).


 * Subject to your interest, and as warranted, I'm keen to continue the discussion in WP:CIVIL manner. I hope I've kept the SQ (snarky quotient) to a minimum. Sandbh (talk) 04:02, 8 October 2020 (UTC)

Suggestions DS1: blocks alone
Since has previously talked about some possible category mergers, and has so far said "Though I am not yet prepared to give up our enwiki metalicity categories", here is an explanation of why I like blocks alone as categories.

Firstly, if we look only at the categories of metals, the blocks actually stand out as particularly natural mergers of similar categories.


 * s-block: We are, I think, in agreement that there is not a significant difference between these (excepting Be and to some extent Mg) other than the valence. Where we disagree is whether there is a good name in the literature that has equal recognisability to the "alkali" and "alkaline earth metals" categories, that could be a replacement for a merger of the two. As expressed above, I don't think either "active metals" or "light metals" really cut it for our purposes. But it seems to me that there is a fair replacement: s-block metals. The term s-block is obviously common in the literature (IUPAC in the Red Book refers to blocks too, albeit not defining them), and it contains exactly the elements we want.

If we use an "s-block metals" category, then consistency of theme suggests that we carry on with the block theme for the rest of the categories as well. Luckily, this is almost exactly what we already have.


 * f-block: YBG has previously suggested a merger of the lanthanides and actinides. I tend to agree that this would be a good idea; the differences between them are about the same order as the category-internal ones within the transition metals. It so happens that IUPAC in its Red Book already gives the name "inner transition element" for the f-block elements, so "inner transition metal" could be fine. "Inner transition element" seems to be equally official to "lanthanoid" and "actinoid". However, for consistency of theme, I think "f-block metals" would be preferred. An advantage of this is that, going one step closer to fulfilling YBG's rule #6, we lose the overlap that occurs between the Ln/An and the TM at the edges of the categories.


 * d-block: The current "transition metal" category can be extended to the other IUPAC-allowed sense of groups 3–12 rather than 3–11 to match the d block. While it is true that the group 12 elements do display a significant reduction of metallic character, and a loss of the typical transition metal property of easily variable oxidation state, to my mind this is not a deal-breaker. Firstly: we used to have it this way. Secondly: it's very common to have it this way especially at the introductory level. Thirdly: in terms of coordination chemistry, the Zn group is actually not so far removed from the Cu group. Fourthly: this reduction of metallic character is more or less what you'd expect just because the block has ended – you start to get a similar reluctance to oxidise beyond +2 at nobelium as well. Fifthly: groups 3 and 4 also have weak expression of anything but the group oxidation state (even for Ti, +3 is readily oxidised to +4), as do Nb, Ta, and Db in group 5, but no one tries to remove them from the transition metals. Sixthly: the elements Zn, Cd, and Hg do show usage of their d orbitals for chemistry, which is like the metals of groups 3 through 11 but unlike the ones in groups 13 onwards. Therefore, I submit that the old group 3–12 definition, approved by IUPAC as it is, is more internally consistent with regard to how group 3 and group 12 are treated. Since the literature is somewhat evenly split, this should be no problem.

An advantage of using "d-block metals" instead of "transition metals" is that we no longer need a footnote about group 12 to be spread everywhere, incidentally.

Regarding the exact composition of group 3: I still think I am going to propose Sc-Y-Lu as the first-placed one, with Sc-Y-La as the footnote, as Polish Wikipedia does. There are a few reasons for this. It goes without saying that this is how I see the issue, and there is no obligation on anyone else to accept it.
 * 1) This is what the majority of participants in this project's discussion have supported. I support it; User:Droog Andrey supports it; User:YBG supports it; User:ComplexRational supports it; User:Dreigorich supported it when he was here; so did User:Officer781. In opposition we have User:R8R (who seems to personally support it but have qualms regarding whether or not it's the best reflexion of the literature), and User:Sandbh (who, of course, recently published an article supporting Sc-Y-La). In the following points I hope to address your opposes.
 * 2) IUPAC isn't of very much help here, because they are in the middle of deciding the issue. The 2005 Red Book shows a Sc-Y-* table, but the task force that is deciding on group 3 is explicitly not considering that as an option. The 1990 Red Book, which besides the 18 column form also shows an 8 and a 32 column form, however does show Sc-Y-Lu in the 32 column form (whereas Sc-Y-* is shown in the 8 and 18 column forms). Moreover, the context behind the compromise on Sc-Y-* seems to be between a majority showing Sc-Y-La and a minority pointing out with arguments (that convinced Fluck, who prepared this report for IUPAC) that Sc-Y-Lu was better. Therefore, as far as IUPAC recognition goes, it seems to me that Sc-Y-Lu is not out of the question.
 * 3) If we consider the sources that consider the issue of periodic table placement, a majority tends to support Sc-Y-Lu: see User:Double sharp/Group 3 sources for an as yet incomplete list of such sources. There is a precedent for considering majority status in such cases rather than across all textbooks when the tenor of the journal sources is that textbooks are in error: consider the case of hypervalence, where most textbooks will tell you d orbitals are involved for main group elements, but journal articles focusing on the matter will insist that they aren't. Here we follow the journal articles. Admittedly, the number of Lu articles is inflated by the fact that most of these authors seem to think that one argument is enough to resolve the whole issue, whereas the most prominent La article (Sandbh's) collects many arguments. While I am in agreement that really only one argument is necessary, this is a point that can be discussed. But I believe points 4 and 5, not to mention 6, partly address this.
 * 4) Sc-Y-Lu is not confined to journal articles. It also appears both in popular science books about the elements (e.g. John Emsley, Nature's Building Blocks) and standard textbooks about chemistry: Clayden et al.'s Organic Chemistry, Jerry et al.'s Techniques in Organic Chemistry, Oxtoby et al.'s Principles of Modern Chemistry, Jones and Atkins' Chemistry: Molecules, Matter, and Charge. And, of course, it appears on the common resource WebElements. It seems unlikely to me that new readers will be unfamiliar with this form.
 * 5) The most prominent La source, which is currently User:Sandbh himself, magnanimously notes that "different approaches to the Group 3 question...will continue to have their uses", and stresses the need to explain the relevant context. The context of this is an introductory-level article on the periodic table. The Madelung rule is surely going to be listed, but we don't really have the time to go into the individual chemistry of the group 3 elements and their neighbours as Sandbh's article does in order to support Sc-Y-La. Leaving aside the question of whether I agree or not with his analyses (I don't, and I think chemistry, while not so relevant for the question, supports Sc-Y-Lu as well), it seems to me that if the context is just an introduction with the Madelung rule given as a match for the periodic table's structure, a Sc-Y-Lu table is more appropriate for this context because it better matches the Madelung rule's statement: 4f before 5d, not one 5d hanging up before 4f starts.
 * 6) If we are going to do a block-based scheme, then it seems to me that the argument we have stated above becomes quite important. La and Ac have low-lying f orbitals that are implicated for their chemistry, whereas Lu and Lr have no such thing. In fact, the 4f and 5f orbitals of La and Ac are available for hybridisation and are occupied in excited-state configurations that are low-lying enough to have a significant impact on chemistry, but this is not true of Lu and Lr. Importantly, this also treats Ac and Th analogously: both don't have 5f occupied in the ground state, but may use it anyway. That isn't just our original research, but is also pretty much the argument used by Jensen in this paper. It seems to me that this becomes especially important if we outright call the blocks out: it's very odd to call Lu an f block element, when it doesn't have f valence involvement. You can either take this as I do as a statement of general importance, or following Sandbh's approach as looking at the context: if the context is a block-based scheme, then Sc-Y-Lu seems more relevant.
 * 7) The secondary relationship that even Jensen grants from La and Ac to Sc and Y seems to be slightly more graphically obvious (yes, I know, weak argument) in the Sc-Y-Lu form, than the relationship from Lu and Lr to Sc and Y is in the Sc-Y-La form. In this form, we have Sc-Y-Lu-Lr vertically aligned in group 3, but La-Ac can also be vertically aligned under group 3 and preserve the next relationships Rayner-Canham (among others) has noted of Th to group 4, Pa to group 5, and U to group 6. In the form Sc-Y-La, it isn't possible to preserve the relationship to Lu and Lr, which end up falling under group 17 (which isn't related at all). Faced with a visual distinction between Sc-Y-Lu-Lr-[gap]-La-Ac, and Sc-Y-La-Ac-[gap]-[nothing] + F-Cl-Br-I-At-Ts-[gap]-Lu-Lr, I think the former does better.

I believe points 3 and 4 together address the opposition of R8R, and that points 5 and 6 (perhaps also 7) some way to addressing the opposition of Sandbh.

Merely supporting Sc-Y-Lu as a default does not mean that I wish to force it on WP with no room given to Sc-Y-La. On the contrary, I would support continuing to do what we currently do on the infoboxes, i.e. referring to the block Lu is in as "d-block (sometimes considered f-block)", adding notes to the group 3 assignments of these elements stating that they are under some discussion among scientists, and so on. It merely means that I think the context we are writing in is better served by a Sc-Y-Lu default table with a footnote about Sc-Y-La, than it is by a Sc-Y-La default table with a footnote about Sc-Y-Lu.


 * p-block: The last advantage of annexing group 12 to the transition metals, as many texts do, is that the problem of what to call the remaining metals naturally solves itself. They are the "p-block metals". While "post-transition metal" has the problem that Al is arguable, and the other category names aren't really so widespread, "p-block metals" at least unites two common terms: "p-block" and "metal".

This thus neatly divides the metals into four categories: s-block metals (AM + AEM), f-block metals (~ Ln + An), d-block metals (~ TM), and p-block metals (~ PTM). So far, the number of categories has fallen by two.

Now we come to the metalloids and nonmetals. It seems to me rather odd to only use a block division for the metals; it seems to carry a connotation that such a division is not applicable to the nonmetals. This is not true; it's just that most of the nonmetals and metalloids are in the p-block, so we don't get much information out of it. But I think there is a case for more mergers.


 * Halogens and noble gases. It seems to me that since the categories are really the intersections of groups 17 and 18 with "nonmetals", it's not completely necessary to actually call them out. It is not clear in the literature whether "halogen" means the whole group or just the category F-Cl-Br-I or maybe F-Cl-Br-I-At. (To put it another way, it is not clear if Ts automatically becomes a halogen, or if it has to pass the bar of actually behaving similarly to the halogens we already know are halogens.) So instead of making "halogen nonmetal" sound like a real term in itself, it seems to me that's it not necessary to have three separate nonmetal categories when two are just calling out common groups.

An advantage is that we then get one single category: there's no need for "other nonmetals", we just have "nonmetals". Including both current reactive nonmetals and noble gases. Yes, the noble gases are maybe somewhat distinct, but we put noble metals with transition metals, so it seems all right to me. The range of behaviour of the TM category from yttrium to gold is quite extraordinarily large already, so this doesn't seem too bad.

We can get away with deleting one more category.


 * Metalloids. I would personally favour deleting this category altogether. First of all, there is a sort of inherent contradiction in the name: anything that's not a metal should kind of obviously be a nonmetal. Second of all, IUPAC doesn't seem to like it very much, as Sandbh has noted.

Now, what should we do with the annexed elements? The obvious solution is to take the name seriously and to classify them all as nonmetals. But this raises another question: what exactly is a metal? Here the problem is not so much that the term is not used (it is used very often, including by IUPAC) but that it is used without being clearly defined much.

The IUPAC Gold Book sheds a little bit of light on the situation with its definition of metal-nonmetal transition (or metal-insulator transition) here: "A transition characterized by a sudden change in electrical transport properties (conductivity) due to a reversible change from localized to itinerant behaviour of the electrons." But this is a definition for substances, not for elements. There is no definition of that.

In the absence of this, I feel that due to WP:OR it is not a good idea to state exactly which elements are metals and which are not. I am also somewhat in sympathy with this notion: to me it is rather that an element can form a metallic simple substance, and that "is an element a metal" is not a particularly important question to ask. The chemical properties common of metals are not so much defining features, but tend to correlate with the physical ones because easy delocalisation of electrons also tends to imply that they are easily lost. But it's clearly not something universal: germanium doesn't have the physical properties but has some of the chemical properties of a metal (rather weakly expressed, but they're there), whereas tungsten is mostly lacking in the stereotypical high-school metal properties but is physically an excellent metal.

The precise location of the metal-nonmetal line is not agreed on between authors; nonetheless its rough location is pretty commonly agreed. So we can obviously discuss the metal-to-nonmetal trend on the periodic table. But I think it is not a good idea to outright say which elements are metals and which elements are not on WP when there is no clear agreement on that in the literature.

This also has the benefit that instead of the intersections "s-block metal", "p-block metal", and so on, we finally have a complete set of categories that are mentioned by IUPAC in the Red Book and are standard in the literature: "s-block", "p-block", "d-block", and "f-block".

At the level we are looking at, I suggest that this is the most useful presentation for our context. The periodic trend that says that metallicity increases to the left and to the bottom of the periodic table is of course useful to know and can be covered at a general level; but the minutiae of chemical details that are needed to clearly explain why something or another is chosen to be a metal or not are, to my taste, not exactly relevant to something which will be on articles that aren't about the classification issue. At this level, I suggest that only the very basics are needed: the Madelung filling order is among them, as it appears in chemical courses way before the excruciatingly detailed investigations that are needed to decide which of some contentious elements are metals or not, or whether the chemistry merits Sc and Y to be moved (I do not think it does, but you know that already). So I suggest that for the present context, Sc-Y-Lu + blocks alone is enough.

And therefore I propose annexing the metalloid and nonmetal categories altogether to the respective blocks and colouring by blocks alone as follows. Let's call this version DS1A.



Now, if the voices against blocks alone are too strong, I can offer a compromise that still includes the metal-to-nonmetal trend. This would involve colouring categories as "s-block metal / s-block nonmetal", "p-block metal / p-block nonmetal" etc. But it would force us to make editorial calls on exactly which elements are metals. In the absence of some sort of consensus in the literature, or even a sort of consensus with two major options alone as we have for Sc-Y-La vs Sc-Y-Lu, I feel this would go too far into WP:OR and therefore would only go to this reluctantly.

The way I have done it above seems to me to be free of any possible sign of WP:OR, appropriate to the introductory level expected of a template that expects to be used in many different contexts, and has the advantage that there are no more "other" non-categories. The only major IUPAC-acknowledged block-related dispute, far from leading to a multitude of different classifications, can be safely listed in a footnote giving the two alternatives.

You'll notice that I don't list the helium saga because IUPAC hasn't acknowledged it officially.

Finally, this category list shows perfect compliance with all seven YBG criteria:


 * 1) Clear. The division is by blocks alone as the only criterion.
 * 2) Unambiguous. Well, as soon as an author has decided on the group 3 composition, the blocks are straightforward even if not often defined properly.
 * 3) Meaningful. As these valence orbitals are the underpinning of about 100% of chemistry, it seems clear that the division has a real meaning.
 * 4) Referenced. Quite clearly so.
 * 5) Specific. Indeed. There are even no "unknown" elements because the superheavies tend to get provisionally assigned to blocks anyway. That's inherent in where they're placed on the table in the first place.
 * 6) Unique. Clearly, the categories are mutually exclusive.
 * 7) Complete. And equally clearly, they are jointly exhaustive.

Moreover, with just four categories, we are free to have a very clear colour-based distinction. As discussed earlier, even the colours used themselves for the blocks have some degree of standardness!

As the icing on the cake, such a "blocks alone" scheme is in fact not something we're making up ourselves, but is in fact extremely common in the Russian-speaking world. It is also the only exhaustive and mutually exclusive scheme that appears in the IUPAC Red Book: "Optionally, the letters s, p, d and f may be used to distinguish different blocks of elements."

Of course, I would support a discussion of categories in the main periodic table article. And of course, you can see that for the one flaw in this (the ongoing group 3 dispute), a long footnote is added.

Finally, I should note that it is not a must for me that we change back to Sc-Y-Lu in order to use such a scheme (although that would naturally be my personal preference). Such a breakdown into blocks alone, plus a similar reciprocal footnote, can be added just as well with a Sc-Y-La format, and may be called version DS1B.



My preference order is: DS1A > DS1B > Sandbh V5A with PTM changed to other metals and "light nonmetals" changed to other nonmetals > Sandbh V5A with "light nonmetals" changed to other nonmetals > current status quo > others.

Opinions requested. Double sharp (talk) 15:32, 8 October 2020 (UTC)

Sandbh comments

 * From the COPTIC database, only 15% of sources take a "blocks-only" approach.
 * "s-block metals" for a unification of the AM and AEM is a good "crisp" idea.
 * Extending the block approach to the rest of the periodic table on consistency grounds, when there is no such periodic table colour category consistency in the literature has, as I said, no basis in the literature. I feel this hides knowledge.
 * Calling the inner transition metals "f-block metals" is OK by me, as a long as we include the lanthanide and actinide labels in the graphic. As a bonus, f-block metals is shorter.
 * Calling the transition metals the "d-block metals" is not OK by me.
 * With respect to the p-block, all kinds of hell break out here due to the meeting of the metals and the nonmetals. Getting rid of the metalloids and noble gases, and excluding the halogens, is non-encyclopaedic and, I feel, hides knowledge.
 * An encyclopaedia tells the story as it is, as best as it can, regardless of whatever inconsistencies there are in the literature.
 * A 4-category block table belongs to our Block (periodic table) article, rather than being the focus of our periodic table FA.

What do we have then? Quite a bit, in my view. YBG, DS and I broadly support an AM-AEM unification. YBG and I support 4+4. DS and I support a division of the reactive nonmetals; R8R previously expressed in-principle support for such a division.

We're circling around the same star, in slightly different orbits. Crudely and broadly, we have:

† similar; soft; single-valent (+1 or +2); sensitive; some sizzle in water ‡ "footnote" metals ^_^ ¶ we have or haven't discussed:

Notes
 * A. The literature records such terms as (a) "light lanthanoids" and "heavy lanthanoids"; (b) "light actinides" and "heavy actinides"; and (c) "light transition metals" (period 4) and "heavy transition metals" (periods 5 and 6).


 * The (a) and (b) set features a vertical divide; (c) has a horizontal divide.


 * Since the "non-halogen non-inert gas" nonmetals span periods akin to the Ln and An, and groups akin to the TM, "light nonmetals" would then refer to the nonmetals in groups 1 and 14-16, with a vertical divide = 16|17, and in periods 1-4, with a horizontal divide = 4|5. Such an approach is consistent with established nomenclature practice.


 * B. Wulfsberg (2000): "Most of the moderately active metals and nonmetals (the electropositive metals and electronegative nonmetals) are reduced from their oxides…using carbon."


 * Welcher (2001): "The elements change from active metals to less active metals, to metalloids, to moderately active nonmetals, to very active nonmetals, and to a noble gas."


 * Perlman (1970): "Between Groups I and VII there are gradations from active metals (Col. I) to less active metals to moderately active nonmetals to volatile nonmetals (halogens Col. VII)."


 * Sorokhtin at al. (2007): "Nitrogen is a moderately active element, reacting weakly with natural inorganic compounds."


 * Gelender at al. (1959): "This oxidation may be accomplished by: (a) The use of suitable oxidizing agents for moderately active nonmetals."


 * Timm (1950): "Oxygen is a moderately active nonmetal and will combine directly with nearly every other element to form an oxide.

Legend 4 (featuring 4+4)
Per table 1, what distinguishes the halogens is that they're the only nonmetals each having high values for IE and EA and EN. The noble gases are distinguished by, among other things, not having any EA.

In general, the higher an element's ionisation energy, electron affinity, and electronegativity, the more nonmetallic that element is: Yoder CH, Suydam FH & Snavely FA 1975, Chemistry, 2nd ed, Harcourt Brace Jovanovich, New York, p. 58. --- Sandbh (talk) 07:25, 9 October 2020 (UTC)

Shared attributes of the moderately active nonmetals
Here's an update:

The moderately active nonmetals H, C, N, O, P, S, and Se feature a rich array of shared characteristics. Summarising, they are distinguished by their:
 * 1) sub-metallic, coloured or colourless appearance, and brittle comportment if solid;
 * 2) moderate net non-metallic character;
 * 3) covalent or polymeric compounds;
 * 4) prominent biogeochemical roles;
 * 5) proclivity to catenate (form chains or rings);
 * 6) multiple vertical, horizontal and diagonal relationships;
 * 7) uses in combustion and explosives;
 * 8) uses in nerve agents;
 * 9) uses in organocatalysis;
 * 10) interstitial or refractory compounds; and
 * 11) dualistic Jekyll (#4) and Hyde (#7, 8) behaviours, including being unified by their shared attributes despite their diverse individual natures.

10. Capacity to form interstitial or refractory compounds It was known from an early time (West 1931, p. 121) that light nonmetals, including the metalloids boron and silicon, formed refractory (hard, high-melting) compounds among themselves or "interstitial" compounds with some transition metals, often of a similarly refractory nature. It was initially thought that the non-stoichiometry of many of the transition metal compounds suggested the nonmetal atoms were occupying some or all of the interstices in the metallic lattices, without altering the lattice types. The formation of such compounds was then facilitated by the smaller-sized nonmetal atoms and, seemingly, ionization energy values, "sufficiently low to avoid exclusive ionic bond formation" (Glasson & Jayaweera 1968). It is now clear that the lattice types are frequently distorted from those of the host metals (Wulfsberg 2000, p. 791).

The subject compounds include interstitial hydrides (e.g. VH0.05; NbH0.11; TaH0.22)[n1], and refractory carbides,[n2] nitrides (TiN; ZrN),n3 oxides (ThO2; m.p. 3300 °C),[n4] phosphides (PuP)[n5] and sulfides (Ce2S3; ~2000 °C). Here, selenium is a borderline interstitial-compound-former (Goldschmidt 1967, p. 43). In the case of the carbides, many thousands of tons of the refractory interstitial compound tungsten carbide (WC) are produced annually around the world and used in cutting tools, industrial machinery, sports equipment, abrasives, surgical equipment, and jewellery. Refractory oxides can be heated to white heat without melting (Wulfsberg 2000, p. 685). More generally, refractory compounds are used in furnaces, kilns, incinerators, and reactors, and to make crucibles and moulds for casting glass and metals.

In the search to design new superhard materials, there are two main approaches. "In the first, light elements, including boron, carbon, nitrogen and/or oxygen, are combined to form short covalent bonds. In the second, elements with very high densities of valence electrons [i.e. transition metals] are included to ensure that the materials resist being squeezed together. Purely covalent bonding (such as in diamond) is best, and some ionic character is acceptable. However, highly ionic or metallic bonding is the same in all directions and therefore poor at resisting either plastic or elastic shape deformations." (Kaner, Gilman & Tolbert 2005).

Notes
 * 1. (a) The fractions represent the largest amount of hydrogen that can be accommodated without distorting the lattice structures of the host metals (Wiberg 2001, p. 258). (b) In palladium hydride, the lattice is not altered and is never stoichiometric, with no more than 0.8 hydrogen atoms per palladium atom (Wulfsberg 2000, p. 792). (c) Niobium forms a series of non-stoichiometric hydrides NbHx (0 < x ≤ 1) which, at low hydrogen content, retain its body-centred cubic metallic structure (Housecroft & Constable 2010, p. 703).
 * 2. The binary compound 4TiC + ZrC has the highest recorded melting point of 4215 °C (MacKay, MacKay & Henderson 2002, p. 314)
 * 3. (a) A thin film of TiN was chilled to near absolute zero, converting it into the first known superinsulator (cf. superconductor), with its resistance suddenly increasing by a factor of 100,000 (Vinokur et al. 2008). (b) The Boeing company (2010) has a patent for the use of zirconium nitride as a hydrogen peroxide fuel tank liner for rockets and aircraft.
 * 4. Highest known melting point for an oxide
 * 5. Listed as a ceramic material (O’Bannon 2002)

References --- Sandbh (talk) 06:04, 10 October 2020 (UTC)
 * Glasson, D.R., Jayaweera, S.A.A. Formation and reactivity of nitrides I. Review and introduction. J. Appl. Chem., 18: 65−77 (1968)
 * Goldschmidt, H.J: Interstitial alloys, Butterworths, London (1967)
 * Kaner, R.B. Gilman, J.J, Tolbert, S.H. Designing superhard materials. Science. 308, 1268-1269 (2005)
 * West, C.J.: A Survey of American Chemistry, National Research Council (U.S.). Division of Chemistry and Chemical Technology, Chemical Catalog Company, New York (1931)
 * Wulfsberg, G.: Inorganic chemistry. University Science Books. Sausalito, CA (2000).

R8R comments
I think Double sharp’s DS1 proposal has its merit. I am afraid to think, however, that we lose some important knowledge in this scheme. Transition metals and noble gases, for example, are of superb importance and they don’t clash with anything. The metalloid category is fuzzy indeed, but we have a good understanding where it is located in the PT. As an encyclopedia writer, I feel we’re losing out without such categories.

I think Sandbh’s proposal is rather inconsistent. While Double sharp suggested a proposal, in which all categories were chosen based on the same principle (PT block), Sandbh’s table composed mere blocks with actual chemical categories. I don’t believe this is good, and my feeling is strong about this. To mirror Sandbh’s words, if it’s not okay to call transition metals “d-block metals” (something Double sharp never proposed in the first place: he went for “d-block”) then by applying the same principle, it is not okay to call alkali and alkaline earth metals “s-block metals”. In both cases, chemical names are known very well. I could see us use DS1 even if I think we’d lose lose out a bit by doing that; I can’t see us combine “s-block metals” and “transition metals.”

Our goal is to reflect common knowledge. We are losing out by ignoring those two well-known names and going for generic “s-block metals,” especially if this is inconsistent with other names. The same goes for “f-block metals”.

For an encyclopedia writer, reactive nonmetals leave room for discussion. The same can’t be said of either the s-block or the f-block, where we have four well-known and IUPAC-approved names.—R8R (talk) 11:15, 10 October 2020 (UTC)
 * Thank you for your comment. I would like to wait on a reply before the ANI thread reaches a conclusion and we know how the discussion should proceed from here on, but I want to make it clear that I have seen it and will think about it. ^_^ Double sharp (talk) 12:41, 10 October 2020 (UTC)


 * I'd like to continue the discussion regardless of ANI. I feel stressed by ANI. In contrast, it's good to be able to discuss matters here amongst knowledgeable colleagues. YMMV however.


 * I have no particular stake in retaining "s-block", or "f-block metals". I supported the "s-block/s-block metal" suggestion since a merge of the AM and AEM has good support from three of us. Since all of the elements in the d-block, as far as we know, are metals, I treated the terms "d-block" and "d-block metals" interchangeably. So, I'm happy to keep "transition metals" even though that term is neither approved nor endorsed by IUPAC! So much for consistency! ^_^


 * Like the metalloids, the orphan nonmetal category can be fuzzy, but we have a good understanding of where it is located in the PT.


 * Regarding consistency: I submit there is no such thing in the literature. As I see it, we are once again seeking to hold ourselves to a standard with no basis in encyclopaedic terms. I say "we" in the sense of our project, absent of informal consensus., as you wisely observed, if one wants to write a book one can "consistently" knock one's self out in any way one likes; in an encyclopedia this is unjustified and uncalled for.


 * There is no need to lose out on AE and AEM. I have previously suggested adding a note to the legend saying that in the unified colour category, group 1 are the AE and group 2 are AEM. Nothing is lost.


 * I have no stake in f-block metals. I was trying to retain the best parts of Double sharp's suggestion. I'm not sure what the issue is with f-block metals, in any event. It doesn't hide anything. The Ln and An labels can be retained. As noted, there is no consistency in the literature on these matters and I'm puzzled as to the WP- or encyclopaedic-basis for raising a concern about this. Even IUPAC, for once, recognises the optional use of the letters s, p, d or f to distinguish blocks.


 * The term "reactive nonmetals" has little support in the literature (ngram = ~1). It conceals a relatively extensive amount of knowledge—included a marked distinction between the halogens F, Cl, Br, and I(At), and the orphan nonmetals—rather than reflects knowledge, and is non-encyclopaedic from that perspective.


 * For the category names of s-block or f-block metals, nothing would be lost. The four approved IUPAC names will continue to appear in the graphic. Knowledge would be added rather than concealed via "s-block" and "f-block"; reader interest has the potential to be piqued, in the best tradition of any encyclopaedia.


 * The Red Book says, "the elements of groups 3–12 are the d-block elements. These elements are also commonly referred to as the transition elements, though the elements of group 12 are not always included; the f-block elements are sometimes referred to as the inner transition elements." Therefore, "transition elements" and "inner transition elements" are acknowledged by IUPAC. There is no acknowledgement for a name for the s-block metals.
 * I have not made a comment on reactive nonmetals; I merely said that there is room for discussion. This is not something I'd want to discuss at the present moment.
 * The best part of Double sharp's suggestion is that it only features blocks, leaving aside all questions like what is a metal, not to mention which nonmetals are very reactive and which are merely moderately nonreactive. Back when I went to school, the periodic tables in both the chemistry classroom and the physics classroom featured only blocks. Having three categories in the s-block, one in the f-block, three or four in the d-block, and five in the p-block defeats the entire point of DS's suggestion.
 * Let's try and mirror the note argument. Say, we'll leave the AM and AEM categories and add a note mentioning "very reactive metals" or any other name suggested below for it. Would that note make much sense? I'd say not, and as such, it seems clear AM and AEM are more important, and that's what we should strive to reflect as an encyclopedia.--R8R (talk) 14:17, 11 October 2020 (UTC)
 * Thanks. I've seen this too. ^_^ Double sharp (talk) 18:42, 11 October 2020 (UTC)

The Red Book + blocks
Thank you R8R. Good to hear from you.

We have chosen to ignore the Red Book, since we use "transition metals" yet that is neither endorsed, recognised or approved by IUAPC. Rather, "transition metals" is an adaptation. The IUPAC Red Book says, "Optionally, the letters s, p, d and f may be used to distinguish different blocks of elements." In the same way, "s-block metals" is an adaptation. Mostly this question has become superseded since, according to the literature, the preferred term is "Early main group metals", per the twenty-five quotes listed below.

We have chosen to further ignore the Red Book by including metalloids but not including rare earth metals—an IUPAC-approved term—and despite the popularity of this term or variants in the literature, being ×2.5 as popular as "noble gases", for example.

After IUPAC (1970) recommended abandoning the term metalloid, its use increased dramatically. Google's Ngram Viewer showed a ×4 increase in the use of the word 'metalloid' (as compared to 'semimetal') in the American English corpus from 1972 to 1983. There was a ×6 increase in the British English corpus from 1976 to 1983. As at 2011, the difference in usage across the English corpus was around 4:1 in favour of 'metalloid'.

I suggest The Red Book is a consideration but as well being outdated and unclear in itself, parts of it are widely ignored by the chemistry establishment.

On blocks, the COPTIC database shows that only 15% of textbooks show just the blocks; 35% show metals-metalloids-nonmetals; 50% show categories. That is why I'm not in favour of limiting our table to just blocks. It's not reflective of the literature, and is non-encyclopedic since such an approach hides knowledge—knowledge which is easily displayed in a graphic.

I don't understand the mirror-example basis for adding a note to the legend saying the AE and AEM are very reactive. We don't add a note saying the metalloids are chemically weak nonmetals, or that the halogens are very reactive nonmetals. Or that while we show astatine as post-transition metal, it is a halogen according to the Red Book.

Since the PT graphic appears in the lede, it is more of a high-level summary. As such, YBG's aim for 7±2 is a relevant consideration. In this context, I suggest the following quotes from the literature are relevant too:


 * "The chemistry of these elements [AEM] resembles that of the IA metals to a large degree. (Hamm 1969, p. 369)"
 * "The difference between the Group I and Group II elements (except Be) is more of degree than kind." (Choppin and Russell 1972, p. 334)
 * "Alkali (Group IA) and alkaline earth metals (Group IIA) share a host of common physicochemical attributes." (Arevalo 2016)

Also relevant, as noted, the chemists refer to the group 1 and 2 metals as early main group metals, which is precisely and concisely captures the alkali metals and alkaline earth metals, and is more accurate than either individual term, neither Be nor Mg being AE for example.

As an encyclopedia, we can get closer to 7±2 AND we can retain the AM and AEM by way of adding a note to the legend. There is no need to settle for an "either (x) or (y) but not both" outcome. I have tried to show this in the accompanying basic value template (from Hampden-Turner’s (1994) dilemma theory). --- Sandbh (talk) 03:04, 12 October 2020 (UTC)


 * I somewhat agree that we shouldn't use a category just because the Red Book includes it. Still, I consider such an inclusion an important argument for its usage. I recall you said that the Red Book mentioned the "noble metals" as a way to support your argument back then (it doesn't, but that's beside the point). I feel it would be inconsistent to agree with it on one occasion and not agree on another.


 * I feel that the COPTIC argument, as it is stated, is incomplete. What kind of categories does it primarily use? Bocks, after all, are categories, too, or is it blocks vs. metal-nonmetal vs. anything else? What info you have given is not sufficient to make an argument on its own, though maybe there is more to it. By any chance, do those categories include alkali metals and alkaline earth metals?


 * That's precisely it. It doesn't make much sense to add the reactive note if such a category is not present, but it does make sense to include a AM and AEM note if these categories aren't present. That is because AM and AEM categories are encyclopedically important, and "reactive metals" are not nearly as much. (The astatine argument is unclear to me and seems to be an argument against notes in general.)


 * It doesn't matter if the categories are similar. What matters is that any common category is much less common than either AM or AEM. We should reflect sources rather than make a perfect categorization.


 * I tried to see how common the term "early main group metals" really is, and Ngram tells me this: Ngrams not found: early main group metals.


 * 7±2 has nothing to do with being an encyclopedia. It is a good rule, but it has nothing to do with writing an encyclopedia, and it's only approximate anyway. I'd much rather sacrifice the reactive nonmetal division because while "reactive nonmetal" is not a common term, neither is "other nonmetal" or whatever it might be.


 * We need to follow sources, not try to create a better categorization than most sources would do. "Alkali metal" is a well-established compound noun; "early main group metals" is not.--R8R (talk) 19:45, 12 October 2020 (UTC)

Since IUPAC recommendations have a notable record of being ignored I’m not sure why (necessarily) a category recognised by IUPAC counts as being an important argument for its usage absent of other considerations. In any event I'm supporting the inclusion of the AM and AEM as notes to the legend, as a synergistic outcome. On noble metals I never said the Red Book included them. If I did then I’d be fascinated to see where I did. If noble metals had indeed been included in the Red Book, I would’ve been trumpeting that to the world, which I didn’t, since it isn't.

The COPTIC database is based on the “lede” periodic tables in 62 more recent chemistry textbooks. Only 15% showed blocks only; the rest showed metals-metalloids-nonmetals and/or sundry categories. About 8%[!] showed AM and AEM. Your ngram experience is the same as mine. That said, I provided 25 quotations (1978−2020) for "early main group metals"from the literature, and there is a lot to them as it turns out. As Double sharp helpfully observed there was never a historical effort to ensure equal support for the use of all categories. Instead, there was the usual iterative interaction between science and theory or observation, and classification science. Early classification schemes get superseded by “better” schemes, in a stop-start, in whole or in part, in a haphazard fashion, across different fields. Hence there is no perfect scheme, as you said. All we can strive for is an encyclopaedic representative scheme.

7±2 is a good aspiration to keep in mind when trying to break down a complicated concept into digestible reading and learning chunks. I sometimes do that here with a big bullet point list. I break the list up into units of five bullet points. This kind of “conceptual chunking” approach is highly relevant in writing for an encyclopaedia.

We need to follow the sources in an encyclopaedic manner. “Encyclopedia” means “complete instruction" or "complete knowledge”. They do this by drawing on the literature and applying judgement as to the best way depict or attain complete knowledge. The founders of the original WP PT categories attempted to do the same thing. Sandbh (talk) 07:51, 13 October 2020 (UTC)


 * That's not exactly what I said. I said that historically, the categories were never intended to be mutually exclusive and jointly exhaustive; they were only intended to group together similar elements. I then said that it hence isn't a surprise that trying to make them so inevitably leads to either "other" leftover categories or categories without significant name recognition. Therefore I submit that there is no point in striving for an "encyclopaedic representative scheme" when many sources seem uninterested in creating any such scheme at all. They seem only interested in creating a bunch of categories without paying any attention to how good the boundaries are. In that situation, any complete scheme we create at all cannot possibly be representative.
 * I feel that it is not correct to apply such judgement to find the "best way" to depict or attain complete knowledge. That is something that should be done only if one has one's educator hat on, to take a leaf out of User:EdChem's book. It's a matter of applying judgement as to what the relevant literature as a whole is saying, even if we think that that is not complete knowledge. Double sharp (talk) 09:39, 13 October 2020 (UTC)

I tend to agree. When I have read authors writing about their category decisions they acknowledge the fuzzy boundaries in some fashion, usually explaining the reasons for this or that decision, sometimes noting differences of opinion, and then they move on. The schemes involved are representative to the extent that each supports the author in setting out the subject matter of their book. That’s all. Of course, they do pay attention to the boundaries only to the extent they feel it is necessary to do so. That goes back to the classic line about not losing sleep about the hard cases as long as the scheme provides an economy of description and is beneficial to the structuring of knowledge and our understanding.

A good example of an encyclopaedic PT is the Encyclopedia Britannica colour category periodic table. Here we have a table that matches ours mostly, except it notably divides the nonmetals into other nonmetals (inc. mushing in the metalloids); halogens; and NG. I looked into the history of the EB table; it predates the WP colour category table! That’s what I call an encyclopaedic PT! Good enough for them; should be good enough for WP. Note theirs is better than ours in that it includes the rare earths as a category, with the Ln mentioned in the legend as a subset of the RE, consistent with IUPAC (although IUPAC refer to REM rather than REE, but TM as TE—go figure).

In any event, with the gold standard delineation of the metalloids, there are no overlaps worth worrying about other than what we say about atypicality at the boundaries in each category, in the four WP articles I mentioned. To the L of the metalloids are the AM, AEM (separate or merged), TM, Ln/An, and “fusible metals” (another term found in the literature); to the R are the CHONPS or whatever nonmetals, halogens, and NG. That’s where the literature overall has settled down. I’ve been watching more recent mentions of the metalloids and my impression is that they are more consistently than ever converging on the gang of six.

BTW any group 1 and 2 merge should be first tested via an RFC on the PT talk page. I don’t believe that would be required for a split of the reactive nonmetals given we have had such a split for most of the history of our PT colour categories. We could not think of something “better” than other nonmetals. Well, it turns out there is such a literature-based term in the form of moderately active nonmetals, as suggested to me by an off-list chemist when I asked him how he felt about light nonmetals. Sandbh (talk) 10:36, 13 October 2020 (UTC)


 * I feel that the applicability of this argumentation is somewhat dependent on where one stands. I feel there is a sensible inconsistency between these two phrases, which come from the same paragraph: "since IUPAC recommendations have a notable record of being ignored I’m not sure why (necessarily) a category recognised by IUPAC counts as being an important argument for its usage absent of other considerations" and "If noble metals had indeed been included in the Red Book, I would’ve been trumpeting that to the world." Inclusion in the Red Book should either be consistently a strong argument or consistently not be a strong argument (I wouldn't presume you were talking about trumpeting what you did not consider a strong argument). My own take is that it's a strong argument, even though it's not decisive.


 * The phrase about the noble metals is this (from ): "no mention of noble metals, a popular and IUPAC-endorsed name." I would expect that an endorsement from IUPAC should be stated in the Red Book of all places, so that's why I looked there. If you meant a different endorsement, please let me know.


 * Okay, that's really interesting. 15% showed blocks and 8% showed AM and AEM. What did the other 77% show? Could it be that most of these sources merely showed metals, and only metals? I feel that what we know so far is not enough to make a solid argument based on this because we still don't know what exactly the majority of the sources in that database says, but this argument could potentially be expanded upon.


 * "7±2 is a good aspiration" -- yes, and let's leave it at that. I was merely doubting this particular phrase: "As an encyclopedia, we can get closer to 7±2." Indeed we can, but we simply can get closer to seven plus-or-minus two by ourselves, not as an encyclopedia. I feel that as an encyclopedia, we may have as many categories as we should; seven plus-or-minus two is a good consideration but not an encyclopedic one. I'm not rejecting it, merely clarifying what exactly words are worth here.


 * "“Encyclopedia” means “complete instruction" or "complete knowledge”" I actually never knew if that was the case. Our encyclopedia article says, "The word encyclopedia (encyclo|pedia) comes from the Koine Greek ἐγκύκλιος παιδεία, transliterated enkyklios paedia, meaning "general education"" -- that's not quite the same, wouldn't you agree? (I remember reading that Jimbo Wales thinks that a very rare point of view, however correct, should not be featured in Wikipedia, and that was the consideration that raised my suspicion about that etymology.) Anyway, we can always give more knowledge in the article text, we can describe both "pnictogen" and "metalloid" even if the two overlap. We don't need to describe both in our general PT.


 * "The founders of the original WP PT categories attempted to do the same thing." -- I can't help but think this is a very retrospect statement. In what way could one know that? Those founders came up with "alkali metals", "alkaline earth metals", "lanthanides", and "actinides," after all, so the argument could very well be in favor of keeping those categories.--R8R (talk) 11:37, 17 October 2020 (UTC)

Noble metals
Red Book significance. R8R, thanks for your interesting response. On the significance of the Red Book, I agree it's a consideration. Is it an important one? You think it is, which is fine. I think its importance requires a degree of judgement. For example, if a category is in the Red Book does this merit its inclusion in a metallicity colour category PT? No. We do not show rare earth metals; pnictogens; chalcogens; or halogens, all of which are in Red Book. If a category is not in the Red Book does this imply we should not include it in a metallicity colour PT? No, it does not. We include lanthanides; actinides; transition metals; metalloids; and reactive nonmetals even though none of these are found in the Red Book. Clearly the importance of the Red Book is vague. What "annoys" me is then making arguments based on the Red Book to suit one's position absent of what clearly are many other considerations.

IUPAC and noble metals. I was wrong about IUPAC endorsing "noble metals." What I wrote was:


 * "Our colour categories appear to be arbitrary in at least three aspects:


 * 1) no mention of rare-earth metals, a popular and IUAPC-endorsed name;
 * 2) no mention of noble metals, a popular and IUPAC-endorsed name; and
 * 3) the absence of two categories for the "reactive" nonmetals, contrary to the literature."

Noble metals is not in the Red Book. I don't know what planet I was on when I wrote that! I may have intended to refer to:


 * IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997). Online version (2019-) created by S. J. Chalk. ISBN 0-9678550-9-8. https://doi.org/10.1351/goldbook.

Here you will the term noble metals mentioned in the entry on furnace pyrolysis. These Gold Book Terminology definitions:
 * "published by IUPAC are drafted by international committees of experts in the appropriate chemistry sub-disciplines, and ratified by IUPAC's Interdivisional Committee on Terminology, Nomenclature and Symbols (ICTNS). In this edition of the Compendium these IUPAC-approved definitions are supplemented with some definitions from ISO and from the International Vocabulary of Basic and General Terms in Metrology; both these sources are recognised by IUPAC as authoritative. The result is a collection of nearly 7000 terms, with authoritative definitions, spanning the whole range of chemistry."

This is not Red Book endorsement. That said, it appears in the Gold Book as a part of an IUPAC-approved definition (which, as I have acknowledged, many chemists ignore, so again, an element of judgement is required).

I see you recently removed the graphic from our noble metal article, as well as an accompanying table of standard reduction potentials. I may revert these deletions, which I feel are consistent with your "no category" agenda, rather than seeking to improve the graphic, accompanying table, or article. A citation required tag for the 0.4 V benchmark would have sufficed, for example, rather than removing the whole table. Your concern about ruthenium and silver could have been addressed with a citation to Rayner-Canham, and his reservation about silver.

Chemistry text book PTs (blocks alone verboten). Of the 62 more recent chemistry textbooks I examined just one (1.6%) showed blocks alone! The other 61 tables added some combination of:
 * metal-metalloid-nonmetal;
 * An, Ln and some variation of TM;
 * the rest of the categories that we do or do not show;
 * group names including AM and AEM (8%); and
 * sundries like main group element; representative element; gas-liquid-solid; main group metal; or metal (main group).


 * 35% show at least metal-metalloid-nonmetal.
 * 50% show at least Ln, An, TM.
 * Two tables (3.2%) showed no classifications.

WP encyclopedia definition. R8R, your extract from our entry on encyclopedia is incomplete. Here it is:


 * "The word encyclopedia (encyclo|pedia) comes from the Koine Greek ἐγκύκλιος παιδεία,[8] transliterated enkyklios paedia, meaning "general education" from enkyklios (ἐγκύκλιος), meaning "circular, recurrent, required regularly, general"[9] and paedia (παιδεία), meaning "education, rearing of a child"; together, the phrase literally translates as "complete instruction" or "complete knowledge".[10]

How do I know what the founders of the WP PT categories thought? I did my homework. You can read about it starting from archive 1 of the periodic table talk page, and there is some related commentary here: Template talk:Periodic table/Archive 1. --- Sandbh (talk) 06:03, 19 October 2020 (UTC)


 * Excuse me, but it is not a matter of my "agenda", whatever that is. It is a matter of the reliable source situation. And the problem was not the 0.4 V cutoff, but the entire table.
 * If you look at the talk page Talk:Noble metals which I pointed to in my edit summary, you will see that I referred to the source situation. For example: from what I see, the sources are only for what standard electrode potentials these elements do have. I am not aware of them making any point about what these standard electrode potentials mean for chemical nobility. Just look at the sources. The first is Wulfsberg, which on the listed pages 247–249 makes absolutely no point about how standard electrode potentials relate to chemical nobility of a metal. It simply draws the redox predominance diagrams for the elements up to nobelium (except Fr and Ra, where I guess data must be thin on the ground, and He which is not interesting to draw for obvious reasons). The second is Bratsche, which likewise makes no such point, but only lists standard reduction potentials. I don't have the third source, but it's cited to one page in what seems to be an appendix, which makes me strongly suspect it is yet another bald list. And the fourth one I know, and it just lists the predicted standard electrode potentials for the superheavies without relating them to the chemical nobility. Putting them there, to cite the table, on this article, hence relating it to the chemical nobility, is going beyond the sources. According to my understanding, that is exactly WP:SYNTH, and I was acting according to policy in removing it outright. Why not just a citation needed tag? Because I am very sure the whole idea of this table being included here is false: there is a blatantly obvious counterexample. Comparing Ru to Ag, the electrode potential is higher for Ag, yet it is also the less noble one. So, exactly as from WP:NOCITE:

If the material added appears to be false or an expression of opinion, remove it and inform the editor who added the unsourced material. The template may be placed on their talk page.
 * I admit I did not inform the editor in question, which now I see I was supposed to, but since User:Achim1999 has been inactive since 2012 it likely would not have made a big difference. The one who added the table was User:AwesoMan3000 in 2016; he's also not very active, but OK, I just informed him about it.
 * Same thing goes for the uncited periodic table mixing together various categories. And we have had already two significant chemistry editors complain about this article on the talk page. First User:Physchim62:

Re polonium: "Po dissolves readily [in dilute HCl] to yield pink solutions of PoII" (from Greenwood & Earnshaw). It seems that this article is currently repeating a substantial amount of original research which has been brought over (in good faith) from German Wikipedia. The simplest way to help our German colleagues would be to clean up the article here! Physchim62 (talk) 22:45, 29 June 2009 (UTC)
 * And Smokefoot:

What about merging this article with Platinum group? Platinum group (or better platinum group metals) is a well defined concept, so we would not have the definitional issues etc. Anyway, I have never heard of the term "noble metal." And I've worked with the area for many years. The IUPAC goldbook (http://goldbook.iupac.org/list_chemistry.html) does not define Noble metals." "Noble metals" is not mentioned in the Dictionary of Inorganic Chemistry Encyclopedia of Inorganic Chemistry). For all we know, the article was initiated by someone unfamiliar with chemistry. Views?--Smokefoot (talk) 00:53, 27 June 2009 (UTC)

...

The article contains a lot of "synthesis", the well-intentioned product of editors earnestly writing about a topic that is pretty poorly undefined. So dont fret about whether this flakey article is complete or not. --Smokefoot (talk) 17:19, 10 July 2014 (UTC)
 * But we may ask User:EdChem to chip in to confirm whether or not I acted according to policy in my removals. Double sharp (talk) 09:13, 19 October 2020 (UTC)

A little bit of homework would have revealed quite a few sources referring to the 0.4 V criterion. As for citing 6–10+ years old talk page discussions, and accepting them in a non-critical manner, well, WP has come a long way since then. Gosh! Noble metals is mentioned in the IUPAC Gold Book! Gosh! Noble metals is mentioned in Hawley's Condensed Chemical Dictionary (1993)! And in the Oxford Dictionary of Chemistry! And in Wiberg! And G&E! And C&W!

A list of standard reduction potentials, plus a citation supporting the 0.4 V criterion, would have sufficed to address your concerns. Not to mention, as I said, a citation for Rayner-Canham's discussion about the status of silver as a noble-metal. What do you instead? You wipe the whole thing so the next editor has to start from anew, instead of planting a few more helpful indicators. With my best R8R German accent: Categories are verboten!

And once again you cite WP policy (WP:SYNTH, WP:NOCITE) rather than adding a cite required tag to encourage an improvement to the article. Obviously we must ban the cite required tag and hunt down those editors who fail to mindless apply WP:NOCITE and instead choose to encourage improvement.

I’m not impressed.

Next we will have to get rid of our FA articles on heavy metals, and metalloids, as these to are too category-focused and, worse, the categories are fuzzy! Sandbh (talk) 04:55, 20 October 2020 (UTC)


 * Oh, yes, they are mentioned. And exactly where are they defined? See User:Smokefoot's comment:

Well I was thinking that the term "noble" is a term used by lay people and chemists alike, but a wide range of metals could be called noble. Thus the term noble metal is appropriate for Wiktionary (http://en.wiktionary.org/wiki/Wiktionary:Main_Page). Otherwise this article will continue to collect anectdotes and possible devolve vs evolve. Let's see if we hear anything from people that edit chemical pages.--Smokefoot (talk) 13:05, 27 June 2009 (UTC)
 * So let's look at each of the sources you present.


 * What is in the IUPAC Gold Book? Nope, there's no definition of "noble metal". As you admit it appears only in passing in the entry on furnace pyrolysis: "In the case of mercury this can also be done by amalgamation with a noble metal." No definition is supplied, much less one that mentions the electrochemical idea. The term is simply thrown out there.


 * Hawley's Condensed Chemical Dictionary: does it really have the term "noble metal"? According to a Google Books search, no! The closest it gets is the entry on "sacrificial protection": "For example, when zinc is in contact with a more noble (less reactive) metal in the electromotive series". So it isn't even using "noble metal" as a specialised term, it just uses "noble" as an adjective to mean the opposite of reactive. Of course, we then should note that on the electromotive series iron and lead show up as more noble than zinc. And exactly how either of those could be called "noble metals" is as clear as mud. Iron rusts. Lead is kind of the poster child of base metals, as evidenced by how alchemists kept trying to turn it into gold.


 * And if Google Books is anything to go by, the Oxford Dictionary of Chemistry does not have an entry for "noble metal" either. It simply occurs in passing in the entry on "aqua regia": "...will dissolve all metals...including such noble metals as gold and platinum, hence its name ('royal water')." So we still have no definition! All we know is that Au and Pt are among them.


 * What about Holleman and Wiberg? They use the term, but they don't define it. On p. 1328, it finally, for once, uses the standard potentials. But what it says is "According to the standard potentials (cf. potential diagram below), titanium is a non-noble metal (less noble than zinc, but somewhat more noble than scandium; cf. Append. VI)." And on p. 1291 they make it crystal clear through words like "more noble" that to them noble is simply an antonym of "reactive". They still don't define exactly what metals they think are noble (they just say at one point that Hg is one of them), and in this comparison they are still not supporting the ability to rank the noble metals explicitly because they're only ranking non-noble ones (Zn is far from being noble).


 * Greenwood and Earnshaw is just a bald use of the term without definition: "certain refractory or noble metals" on p. 612, "purify noble metals" on p. 790, "coated with a noble metal" on p. 862. Ah, the next one at least gives it a historical use: "It was because of their resistance to attack by air, even when heated, that gold and silver were referred to as noble metals by the alchemists" (p. 1179). Still not a complete definition and it's explicitly explaining a historical usage. Is anyone surprised at this point to hear that the term does not appear in the index?


 * Finally, "noble metal" does not appear in the index to Cotton and Wilkinson either, which raises suspicion that it's not actually universally regarded as a term but just as an adjective "noble" with the meaning of "not reactive" modifying a noun "metal".


 * So, no. No source for the standard reduction potentials would have addressed my concerns. What is still missing is a source that clearly gives the idea that these things are related to chemical nobility of a metal by using it to compare actually noble metals. Holleman & Wiberg comes the closest but I see no comparison between actual noble metals there, only confirmation that Ti is not noble. And we'd still be missing any other sources that might make it clear if this is a standard pedagogical idea or just one that one textbook adopted.


 * So, yes. Of course I wipe the whole thing, because looking at this situation, a new editor should not be starting to overreach from the sources like that anew!


 * This stuff has been in the article for years. There has been ample time for citations to be found that explicitly support the idea. Where are they?


 * As for heavy metals, the FA: I remind you of what User:Smokefoot wrote on the talk page.

Shakey foundations

The article is premised on weak or non-existent definitions. Otherwise the lede or lede+1 would be loaded with high quality references. The opposite is found here. It is thus, in my opinion, a well intentioned OR project dressed up with a lot of jargon. If Wiki administrators or whatever want to evaluate important topics, they should first of all make damn sure that the topic is a topic, and not some loose term that caught some random editor's fancy. We all fall in love with topics and write a lot about them, me too, but that affection is not the foundation of an encyclopedic topic. Having said that, the article does no harm. --Smokefoot (talk) 13:26, 6 June 2016 (UTC)


 * Yes, you answered him with sources, but how reflective are the sources of the wider literature?


 * Therefore, no. It's not "categories are verboten". It's simply "this category is not clear, and even what's used to define it is not clear". So we should not harp on one particular definition, when there seems to be no agreement in the literature on it, and simply state that the term has been used with a variety of meanings and some have defined it in different ways. Full stop.


 * But let's have User:EdChem opine too. Double sharp (talk) 09:12, 20 October 2020 (UTC)


 * and, please STOP! This is going in an increasingly unhelpful direction.  I will expand upon this in my next post, but please both stop.  EdChem (talk) 10:17, 20 October 2020 (UTC)


 * , you posted that Double sharp I see you recently removed the graphic from our noble metal article, as well as an accompanying table of standard reduction potentials . I may revert these deletions, which I feel are consistent with your "no category" agenda, rather than seeking to improve the graphic, accompanying table, or article. A citation required tag for the 0.4 V benchmark would have sufficed, for example, rather than removing the whole table. Your concern about ruthenium and silver could have been addressed with a citation to Rayner-Canham, and his reservation about silver.

This needlessly addresses a content issue with a behavioural complaint. The diffs quoted are approaching two months old and have gone unchallenged since then, which suggests that it has either gone unnoticed or was controversial. Yes, applying BRD, you could revert it but I think that would be inappropriate because (a) the change is not recent in the sense of last 24 hours or so and (b) started an article talk page discussion at the time. A more appropriate response would be to join the discussion that was started. If you have good content reasons to oppose the change, you should be able to persuade others in a content discussion at the article talk page. If there are insufficient participants, you can seek a third opinion, or come here... but keep the discussion on the content of the change. Attributing the edit to an agenda on Double sharp's part risks derailing the discussion into a personality conflict.


 * To address what I guess you are thinking, you have the choice to ignore the behavioural concerns that you have and to play a straight bat to the content topics, or you can decide to act on the behavioural issue. If you decide that you need to act (and that is a reasonable decision for you to take), the important point for the sake of the encyclopaedia and the rest of the editing community is that neither here at WT:ELEM nor the article talk page is the appropriate place for that discussion.  One proper approach would be to raise it at user talk:Double sharp.  If that doesn't work, you can seek input from others.  If there are more than two editors involved, or you want to try a more conciliatory approach, you can start a thread at your own talk page and invite others to join you.  If you think it might be a large discussion, you can set up a user space page for it... this has the advantage that if you all come to some conclusion but don't want any harsh words to remain, you could set it up with a header stating that the intention is that it be deleted once it has served its purpose.  You can (collectively) agree a set of rules / guidelines for the discussion that suits you, if you want a different framework.  If these options don't work, you can ask other editors (admin or no) who you trust for their perspective.  You can go to ANI.  But please, keep what you have to say about content separate from content, as far as possible.


 * Double sharp, I can understand why you would be aggrieved by comments on your agenda. You stayed focussed on content in the first reply, for the most part... though it reads to me like there are other comments being made by implication.  Sandbh replies with mentions of being "not impressed" and about homework, which not only reduces the persuasiveness of the content comments, but are also reflective of a level of ongoing antagonism between the two of you.  The tone gets worse as the thread continues.


 * The way the discussion has gone is likely (IMO) to discourage others to weigh in on the content issue, and yet that is actually what you both want. I did look at the article earlier and thought it was another in need of change.  Seeking out references to support a position is understandable when addressing a content point in an existing article.  However, it is risky when writing a new article or doing major changes as it starts from a perspective / understanding which is to be validated rather than starting from the RS and what they say.  It is also helpful to contemplate the comments from outsiders as they can point out situations where the text does not provide a clear understanding or where the interpretations of text leads a reader to infer something other than what the writer meant to imply.  EdChem (talk) 10:50, 20 October 2020 (UTC)


 * Now that I've cooled down thanks to some RL stuff, I'll say: thank you for stepping in before this became worse. I admit that I was rather aggrieved by the comments about my agenda, but I agree that I should not have let that colour my reply. So, I'll let this cool off, and if you want you can comment in more detail and I will contemplate it in silence for a day or two. Double sharp (talk) 12:13, 20 October 2020 (UTC)


 * , I am not surprised that you felt aggrieved. I agree that delaying responding / stepping back to reflect can be an effective way to let your head temper the emotional response that might otherwise be posted.  There are definitely content issues that are worth discussing in the above, and contributions from others are far more likely if the discussion stays content-focussed... which I admit is vastly easier for me to type than for anyone (myself included) to achieve.  I am wondering whether hatting this and starting a new thread on the content in the article, perhaps with a summary of the points made above, might be a good way to reboot this conversation.  Thoughts?  ?  Please note, if a new thread is thought a good approach, may I ask that neither of you try to write the summary of the above points?  Thanks.  EdChem (talk) 21:59, 20 October 2020 (UTC)


 * I think it would be a good idea – though given what we've said, perhaps we should give it a day or two before we start a new discussion on this issue. And I will certainly not try to write any summary of the above points, indeed! ^_^ Double sharp (talk) 23:02, 20 October 2020 (UTC)

Thank you both. Before I post some comments, I respect and value Double sharp's expertise and contributions (mostly) a lot. If I come over snarky that is an honest expression of how I feel. I would probably not do that to an editor I did not know (unless I felt goaded into it). Double sharp and I have been working so long within WP:ELEM that I know not to take offence at well-intended (usually creative) snarkiness. That is one thing I learnt from WP:ANI. There is huge tolerance bandwidth for unacceptable and incivil behaviour. Some of the appalling behaviour I saw there, which resulted in absolutely no action, would never be tolerated outside of WP. Yet it is at WP. So be it.

Anyway, DS and I agree the expression "noble metals" is mentioned in the IUPAC Gold book, not as a definition, but as part of a definition, all such definitions going through a rigorous IUAPC approved process.

Yes, DS, Hawley's Condensed Chemical Dictionary sitting in my bookcase does have a definition of noble metals (1993, p. 834).

Yes, the Oxford Dictionary of Chemistry sitting in my bookcase does have a definition of noble metals (2016, p. 383). See also the online entry.

Yes, as you note DS, Wiberg use the term. Yes they don't define it: I never said they did. They simply draw the analogy to the noble metals (p. 1133).

Yes, as you note DS, Greenwood and Earnshaw use the term. Yes they don't define it: I never said they did. Double sharp: Please don't set up paper tigers and then knock them down.

Yes, as you note DS, C&W use the term. No, it is not in their index; I never said or implied they it was. That's another paper tiger.

Yes, as you note DS, this stuff has been in the article for years. Yes, there has been ample time to put in the citations; no one did, simply like many tens of thousands of other articles. Until some interested editor comes along e.g. in the case of the metalloid article, the heavy metals article. There has been ample time to put in citations, yet no one did simply like the many tens of thousands of other articles. Until I started on the two examples.

The heavy metals article attained FA status on 22 October 2016 and appeared as TFA on November 13, 2016. Smokefoot's older comment of 6 Jun 2016 is no longer relevant, other than as an historical artefact.

There is no time limit on a revert. I didn't revert since I thought it would be appropriate to let DS, as a fellow project member, know of my thoughts, which I did. No I do not intend to turn a molehill into a mountain of discussions; persuading others; getting a third opinion; engaging the rest of the editing community seeking input from others; starting a thread on my own talk page; (collectively) agreeing a set of rules / guidelines for the discussion; or going to ANI (which is akin to the Wild West, in terms of due process). The term noble metals is so widely used within chemistry, being about as popular as noble gases, that all it needs is a few citations, which I intend to provide (eventually). Whole books have been written on noble metals so I expect this will be like falling off a log. Sandbh (talk) 05:12, 21 October 2020 (UTC)


 * I've updated the noble metal article. The standard reduction potential table has bee restored, along with further citations. I've added EN and EA values, and explained their relevance, as per the literature. I'll soon add a PT graphic along the lines of the post-transition metal article graphic. I never knew there was so much to know about noble metals. I can now see why silver doesn't cut the mustard, whereas the other seven noble metals do. Thank you. Sandbh (talk) 06:00, 22 October 2020 (UTC)
 * Any chance of you creating a lists of noble metals article along the lines of lists of metalloids? As long as you've been cracking the books, I think it would be helpful to record the data. YBG (talk) 06:12, 22 October 2020 (UTC)


 * I intend to, now that my interest has been piqued courtesy of User:Double sharp (thank you!). It looks to me to be somewhat of a hodge-podge situation. The oldest reference I saw to noble metals was to gold and silver, in days of yore, being regarded as noble metals whereas the other five metals of old were regarded as base metals. Hg was regarded as a bit of a rouge, up until it was established that it could be frozen. Later on, when the PGM became more well known, they came to be referred to as noble metals, for reasonably obvious reasons. Copper was always regarded as a coinage metal, with coinage being associated with nobility. So the differing historical strands came together, with none of the experts in each field talking to one another, which is not unexpected for scientists, and when someone used the term noble metal they presumed the other people they were talking to were thinking the same thing, whereas of course, this rarely happened. I include here the dentists, who have a tradition of regarding Hg as a noble metal.


 * So you can lift the lid on each so-called noble metal and see how it came to be regarded as such. I only don't know yet why Re supposedly came to be regarded as a NM. It has barely anything going for it: lowish SEP; sub-2.0 EN; and rubbish EA. That's a mystery waiting to be unpacked ^_^ Sandbh (talk) 06:42, 22 October 2020 (UTC)


 * The noble metal article now has an accompanying colour coded periodic table, in the style of our post-transition metal article. There is more work to be done to further improve the article. This is a good start. Sandbh (talk) 23:37, 22 October 2020 (UTC)

And why is all this going into the article now, when it should be clear that it is controversial, and when User:EdChem has already suggested that we reboot the conversation by starting a new thread about the content? Can we not discuss things before sweeping changes are rolled out into the mainspace? Double sharp (talk) 23:51, 22 October 2020 (UTC)


 * Thanks for your interest. Anybody can improve an article anytime they like. As you can see YBG has already taken a keen interest in my efforts to do so. I'm not doing anything different to the approach I took to metalloid and heavy metals. There is no controversy of any significance as I have improved the article consistent with the approach I took to the PTM article, the metal article, and the nonmetal article. As I said to EdChem:


 * "No I do not intend to turn a molehill into a mountain of discussions; persuading others; getting a third opinion; engaging the rest of the editing community seeking input from others; starting a thread on my own talk page; (collectively) agreeing a set of rules / guidelines for the discussion; or going to ANI (which is akin to the Wild West, in terms of due process). The term noble metals is so widely used within chemistry, being about as popular as noble gases, that all it needs is a few citations, which I intend to provide (eventually). Whole books have been written on noble metals so I expect this will be like falling off a log."


 * I don't understand your reference to rolling out "sweeping" change into the mainspace. WP:ELEM does not own any articles in the mainspace. The first improvement I made was to restore (and improve, with citations) the electrode potential table that you deleted. The second improvement was to restore (and improve, with citations) the colour coded periodic table that you deleted. As you said on the talk page, "…I remove the text pending actual citations that use this as a benchmark. For similar reasons I also remove the periodic table." I have now addressed your "pending actual citations" suggestion.


 * Compared to "metalloid" and "heavy metal", and "metals" my experience with improving the noble metal article has indeed been like falling off a log. The force of the literature is strong in this space.


 * As I said earlier, I appreciate having my interest in the topic of noble metals, being piqued by your own interest. It's a much more interesting topic, technically, and historically, then I'd ever appreciated. Funnily enough, one of the references I stumbled upon said:


 * "Table 12: Definition of metal families. Some families like the noble or precious metals or the rare earth elements are well defined, whereas others like base metals, minor or special metals are only loosely defined and overlapping."


 * --- Economic evaluations in exploration (2013), Friedrich-Wilhelm Wellmer, Manfred Dalheimer, Markus Wagner, Springer Science, p. 143


 * Said with no any fuss or bother; simply a statement of the situation. Their table 12 reminds me of the approach we (YBG helped) took in the heavy metals article. I go now to mow my lawns, before it starts raining. Sandbh (talk) 00:36, 23 October 2020 (UTC)

I invite anyone who has concerns bouquets or brickbats about my improvements to the noble metal article, to comment here. Thank you. Sandbh (talk) 00:42, 23 October 2020 (UTC)


 * You have not addressed anything. I have already stated objections following User:Smokefoot's old ones (that, as I see them, still apply ) to your approach of article writing in general). Misplaced parenthesis. Double sharp (talk) 21:16, 23 October 2020 (UTC) You have not given any new citations to the text before the table explaining the relevance of the standard reduction potentials, but simply restored the old references, which I critiqued above. For the 0.4 V cutoff, the source you provide is obviously simply using "noble" as an adjective, because it refers to "the less noble metal (with an electrochemical potential less than 0.4 V)" and "the noble metal (with higher electrochemical potential)". There is nothing in there clearly stating that the "less noble metal" is not also "noble". This usage seems more like "less electronegative", for instance, and no one would expect "electronegative metal" to have a clear bound. One or two people may define one for themselves, but it's hardly going to be a generally accepted thing. All this makes me think that it is rather "nobility" that is the actual chemical idea, that was then applied to metals and gases. It got a clear and accepted new meaning as "noble gas", but for "noble metal" that is hardly clear to me. One of your newly added sources even goes out and says in the first sentence that 'Humans have appreciated the “noble” metals for millennia, yet modern chemistry still struggles with different definitions'. If that's the case, then exactly why is the first sentence of our lede giving a definition "In chemistry, the noble metals are metals that are resistant to corrosion and oxidation in moist air (unlike most base metals)."?
 * And now you just say again that you do not intend to persuade others, and you disparage WP:ANI as "akin to the Wild West, in terms of due process" when the people there are surely much more well-versed in exactly how to interpret WP policy than any of us are. So, are we going to have a discussion to determine WP:CONSENSUS, or not? And are we going to respect WP policy, or not? And could you perhaps understand that just because some of us oppose your views does not mean we are not trying to improve the encyclopaedia? Double sharp (talk) 09:10, 23 October 2020 (UTC)

I’ll consider these concerns and post a response. Sandbh (talk) 09:33, 23 October 2020 (UTC)

1. I object in the strongest terms to your libellous characterisation of my, “approach of article writing in general.”

2. I took the same approach to my work in attaining FA status for the articles metalloid and heavy metal.

3. I have added new content to the noble metals article, with multiple supporting citations explaining the relevance of standard electrode potentials.

4. I do not refer to the entry for 0.4 V as a cut-off, contrary to what you wrote above. Nor do I say that metals above 0.4 are noble metals, nor do I say that metals below 0.4 are not noble.

5. I agree with the concern about the lede. It needs to be better expressed. Do you have a suggestion? There are many better “definitions” set out in the literature.

6. No, I do not intend to persuade others more than I can do by my editing or, by discussions here, as appropriate. Yes ANI is the Wild West of due process, IMO and experience. Ask R8R how he feels. I have zero interest in WP:POLICY and the opinions of the bush lawyers at WP:ANI. I have zero interest in citing POLICY within our project. My only interest is in building a better encyclopaedia and in discussing matters of mutual interest here with other editors. I regularly speak with chemists, authors, or teachers outside WP and I can assure you all we talk about is ideas and viewpoints and, as appropriate, setting out our arguments in the peer-reviewed literature. That is no different to what I do here.

7. There is nothing needing consensus wrt to the noble metals article. It was already there as an article, in need of improving. You removed the PT graphic and the SEP table, pending some citations. IGF I restored the SEP table, improved it, and added new accompanying text and citations. I reinstated a PT graphic supported by citations. That said, I am happy to discuss matters of mutual interest concerning the article.

8. Your most recent contribution was to delete about 7500 characters, and do nothing else apart from waiting for somebody to else to improve the article. I came along and fixed the issues you raised and added a whole lot more, with supporting citations.

9. If your view of improving WP is to remove information you believe to be “wrong”, without providing citations, and then walk away rather than adding a “citation required” tag so as to pique interest in a possible contribution from another editor, then you and I have antithetical world views about how to go about improving WP, and encouraging same.

10. I agree the noble metals article needs more work.

11. I support Smokefoot, when he said, “So dont fret about whether this flakey article is complete or not.” Ditto the old saying, re scientists not needing to lose sleep over the hard cases. It is no longer such a flakey article so there is waaaay less need to fret or lose sleep about it. YBG hasn’t; I haven’t, aside from making some improvements, as thousands of WP editors attempt to do to their articles of interest every day. Sandbh (talk) 10:44, 23 October 2020 (UTC)
 * Thank you for your response. However, your statement I have zero interest in WP:POLICY and the opinions of the bush lawyers at WP:ANI does not give me any confidence that this issue may be resolved in this forum. Therefore, I have elected to take the situation back to WP:ANI at the thread WP:ANI. I hope to see you there, where I hope the situation can be resolved. Double sharp (talk) 21:52, 23 October 2020 (UTC)

4+4 options
All category names are found in the literature. How do these options appear?

Legends 5 to 8
Legend 6

Legend 7

Legend 8

As noted, the moderately active nonmetal category name was suggested to me by a non-WP chemist with several publications, in response to a PM I sent them asking how they felt about the term "light nonmetals". ('Not happy' was the start of their reply).

In all four cases, the labels Lanthanide and Actinide are included in the graphic, adjacent to the start of the 4f row and 5f row, respectively. One note is added under the legend, referring to group 1 as the alkali metals and group 2 as AEM.

Active metals: 16 of the top 20 places in the Standard electrode potential (data page) league ladder for metals are occupied by group 1 or 2 metals. The interlopers are Pr, Er, Eu and Ho, representing the usual boundary overlap.

Light metals: this includes aluminium, per Deming (1940) and Cox (2004). Yes, there are overlaps at the boundaries, once again, since Sc, Y and Ti can be regarded as light metals, too. They are, however, widely regarded as TM. Ra, too can be regarded as a heavy metal.

Bear in mind when considering these options that there are: --- Sandbh (talk) 02:18, 11 October 2020 (UTC)
 * no perfect categorisation schemes;
 * only schemes that are more or less encyclopaedic in nature.

Legend 9 (for the 19th century)
Could be a bit too radical? It's been known since at least 1894 (yep, that's the 19th century; and here we are in the 21st) that metalloids have a predominantly nonmetallic chemistry. Sandbh (talk) 05:34, 11 October 2020 (UTC)

Legend 10 (yes, A & A metals is in the literature)
--- Sandbh (talk) 06:47, 11 October 2020 (UTC)

Legend 11: Early main group metals
Legend 11a

Legend 11b

There it is, this is what chemists refer to the group 1–2 metals as:
 * 1) "The lightest metal lithium (in [LiCH3]4) and the heaviest natural metal uranium (in U6O4(OH)4(SO4)6) undergo metal-metal interactions. The number of compounds with metal-metal bonds formed by the metals lying between these two extremes varies; a maximum occurs in the middle of the transition metal series, and that is where the main emphasis of this article lies. The early main group metals, and the lanthanide form a few compounds of this type, while the post-transition elements form many; combination with transition metals provides a means of forming stable metal-metal bonds for all metallic elements."(1978)
 * 2) "As small-volume cationic charge centers and as a source of unoccupied valence orbitals, the early main group metals have a well-documented but remarkable organometallic chemistry." (1990)
 * 3) "The hope is to further elucidate the nature of these bonds between p-block metals and early-main-group metals and to assess the structural trends within these compounds." (1991)
 * 4) "Recently we have explored the bonding between early main group metals M (alkali or alkaline earth metals) and heavy p-block metals E such as In, T1 (group 3), Sn, Pb (group 4), and Sb, Bi (group 5)." (1992)
 * 5) "carbonyl derivatives of the early Main Group metals are rare and elusive species" (Downs 1993, p. 215)
 * 6) "In addition, this versatile ligand has been shown capable of bonding to the early main-group metals through N…" (1995)
 * 7) "Secondly, the use of phosphorus-carbon ylides (1, where X = CH,) as neutral donors to early main group metals is only a small conceptual step from the use of…" (1995)
 * 8) "…especially emphasizing bonds between transition metals and more electropositive (early) main group metals…" (2000)  (2000})
 * 9) "Three‐center, two‐electron bonds involving hydrogen as a bridging atom are a common feature in the chemistry of early main group metals." (2001)
 * 10) "Predictions as to metals with the unfilled 3d shell and early main group metals having no d electrons are not so unambiguous." (2004)
 * 11) "…has been incorporated into complexes with early-main-group metals…" (2006)
 * 12) "Complexes of the early-main-group metals are only known as polymeric salts [M(NH2)x]" (2007)
 * 13) "This paramagnetic ligand can be stabilized through chelation, eg, to early main-group metals." (2008)
 * 14) "Presumably, this process will occur for any ion with a reduction potential more positive than that of iron and hence gives access to many late transition metals and early main group metals." (2008)
 * 15) "This paramagnetic ligand can be sthbilized through chelation, e.g. to early main-group metals (Canadian Journal of Chemistry 2009, p. 461)
 * 16) "This can to some extent be seen as a result of the greater degree of covalency involved in metal–ligand bonding as compared to more electropositive early main group metals (resonance form B, Scheme 1)." (2010)
 * 17) Molecular early main group metal hydrides: synthetic challenge, structures and applications (2012)
 * 18) "Thus, the synthesis of gallium–gallium multiple bonds, stable chromium compounds with fivefold bonding between the two chromium centers, the unexpected coordination of early main group metals with the f-elements…" (2012)
 * 19) Early main group metal catalysis: how important is the metal? (2015)
 * 20) "Recent years have seen a renaissance in the field of early main group metal chemistry. Breakthroughs were achieved in the isolation of complexes with metals in a low oxidation state (MgI, CaI), “heavy” Grignard reagents have been isolated and characterized (RCaI), the chemistry of strong mixed-metal bases and TURBO Grignards was further developed, and highly reactive heavier alkaline-earth metal benzyl, allyl and hydride reagents have been isolated. Apart from applications in classical synthetic chemistry, early main group metals are increasingly topical in areas varying from catalysis to new materials and hydrogen storage." (2018)
 * 21) "The potential application of early main group metals as catalysts has remained a widely underexplored research field, despite the apparent ecological and economic benefits." (2018)
 * 22) Early main group metal catalysts for imine hydrosilylation (2019)
 * 23) Introduction to early main group organometallic chemistry and catalysis: "This short summary of working principles in catalysis is followed by a discussion on the mechanism of substrate activation by early main group metals… The organometallic chemistry of the highly electropositive early main group metals could not have started without the isolation of these elements in the metallic state." (2019)
 * 24) Early Main Group Metal Catalysis gives a comprehensive overview of catalytic reactions in the presence of group 1 and group 2 metals (2020)
 * 25) "In general, early transition metal compounds, lanthanides, and early main group metals all are strongly oxophilic… (2020)

Precise. Doesn't take up too much room. --- Sandbh (talk) 13:12, 11 October 2020 (UTC)

Legend 11c

There is an interesting Russian connection here (#9):
 * 1) "Organogens - Oxygen, azote, hydrogen, carbon…Sulphuroids. - Sulphur, selenium, phosphorus" (Hoefer 1849, p. 40)
 * 2) "…and are hence called organogens (generators of organic bodies). RETROSPECT OF THE ORGANOGENS (OXYGEN, HYDROGEN, NITROGEN, AND CARBON)" (Stöckhardt 1853, p. 113)
 * 3) "They [C, H, O] are the organogens, without which organization can not exist." (Gatchell 1869, p. 339)
 * 4) Introduction to crystal chemistry, book 2, Moscow University Publishing House (Bakii 1954, p. 458): Treats all the nonmetals, bar the noble gases, as organogen elements i.e. B, C, N, P, O, S, Se, H, F, Cl, Br, I.
 * 5) "There is a considerable variation in the content of the organogens (Ca, K, P, S) and biohalogens (Na, Cl and excess S) in the ash of the discarded plant organs." (Academy of Sciences of the U.S.S.R 1964, p. 157)
 * 6) "The characteristic feature of the litter fall in deciduous forests is the high concentration of the main organogens (Ca + K + P + S)." (Rodin 1968, p. 151)
 * 7) "Organogens should be singled out and subdivided into: (a) absolute organogens without which the existence of organisms is utterly impossible (hydrogen, carbon, oxygen, nitrogen, phosphorus, sulphur, potassium, magnesium)…" (Lapo 1982, p. 93)
 * 8) "The highest selenium content, in some cases exceeding 1 mg/kg, has been found in organogenic soil." (Ylaranta 1988)
 * 9) "…all Russians are selenium-deficient; for this reason, the Chief Sanitarian of Russia G. G. Onishchenko signed in 2000 the Order On Correction of the Quality of Potable Water for the Content of Biogenic Elements[3], including selenium. (Russian Journal of Physical Chemistry, vol. 78, 2004, p. 1980)
 * 10) "Microbes and environment environmental conditions such as temperature, light, nutrition, organogens (C, N, P, S, H, O)." (Rao 2007, p. 27)
 * 11) "It is believed that only certain non-metals C, N, O, S and Se are able to create stable polymeric structures in normal conditions of contemporary environment (Skalny 2011, Bioelementology as an interdisciplinary integrative approach in life sciences: Terminology, classification, perspectives)
 * 12) "It can be seen that most of the essential elements (including organogens) are located in the first few periods of the Periodic Table" (Georgievskii et al. 2013, p. 16)
 * 13) "Biogenic nanoparticles of elemental selenium: Synthesis, characterization and relevance in wastewater treatment" (Jain 2015)
 * 14) "Production, recovery and reuse of biogenic elemental selenium" (Staicu et al. 205)
 * 15) "In roots [the] difference in quantity of organogens and halogens is insignificant – 2.03 and 2.04 mg-eq …(2018) . Comment: Note the distinction between organogens and halogens.
 * 16) "The use of iron electrode at a current density of 300 mA allowed for binding over 96% of the biogenic elemental selenium nanoparticle release from effluent to form stable iron-selenium complex sediments with a reticular structure." (Nancharaiah et al. 2019, p. 122)

--- Sandbh (talk) 03:04, 12 October 2020 (UTC)

Droog Andrey's comments
Vote for DS1A for obvious reasons. Droog Andrey (talk) 21:56, 12 October 2020 (UTC)
 * Thank you! I am working on a more formal proposal for DS1A (explicitly listing sources) according to some help we got on the current WP:ANI thread – should come up soon (but am busy this week). My apologies if this means you may need to !vote again later on the same thing – I am not 100% clear on the protocols. But your support means a lot to me. ^_^ Double sharp (talk) 22:22, 12 October 2020 (UTC)

The Halogens question, again
Again: where or how has it been established that the group halogens is the same as the category "halogens", proposed in these settings? AFAIK, At has not been reassigned convincingly. -DePiep (talk) 20:53, 11 October 2020 (UTC)

Despretz's natural classification (1829–1830)
Wow, how close did he get to DIM? Sandbh (talk) 23:53, 11 October 2020 (UTC)

1−4 Nonmetals 5  Intermediate group 6−14 Metals


 * Bertomeu-Sánchez, J. R., Garcia-Belmar, A., & Bensaude-Vincent, B. (2002). Looking for an order of things: Textbooks and chemical classifications in nineteenth century France. Ambix, 49(3), 227–250.

Legend 12 (with blocks)
Since there is some interest in showing these too.

Out of interest only, I added alt-names. Now with group ranges, too. Sandbh (talk) 06:40, 15 October 2020 (UTC)
 * I have corrected this legend to reflect that hydrogen and helium are s-block elements. Feel free to revert me but please have this consideration in mind.--R8R (talk) 11:44, 17 October 2020 (UTC)



Legend 13 (Blocks up front)
In this arrangement, per, only the blocks are coloured. Helium stays over neon and will therefore show as s-block. The metallicity categories are retained but instead delineated via unnamed dividing lines as per my earlier 16DL post. The category names are situated above or below each dividing line, as appropriate, depending on design considerations.


 * Updated for H in the s-block per DS observation, below. Sandbh (talk) 21:46, 15 October 2020 (UTC)

There is a reduction in the number coloured regions from ten to four, per YBG. The AM and AEM are retained per R8R.

I do worry that giving the blocks so much prominence is not reflected in the literature, per the COPTIC database, but there it is. There is also the lack of any agreed definition of what a block is (other than in an idealised sense) and which elements belong to which block at the boundaries.

The only notes needed in the resulting compact legend are the two IUPAC ones as suggested by Double sharp re group 3, and the PTM. Sandbh (talk) 09:58, 15 October 2020 (UTC)
 * I'll post my explicit proposal in a few days (exact date depending on how busy I end up being), but this is indeed getting closer to what I would like. However, I would not give explicit categories because they don't totally match the blocks (H and He are not alkali and alkaline earth metals) and because if you don't colour things in by categories, and are no longer forced into the not-really-achievable goal of mutual exclusivity and joint exhaustivity, then it suddenly becomes difficult to justify why "chalcogens" is less worthy of inclusion than "CHNOPS nonmetals". That would leave a lot of possible categories and I feel that for simplicity it's better to discuss these only when more detail is needed than a PT template. So, in the PT article, I'd be happy to discuss a whole range of categories, including both post-transition metals (and the other names for that bunch) and pnictogens even though they can overlap. I just wouldn't want to overcomplicate the templates and infoboxes.
 * Also: although there is so far no universally agreed definition of what a block is indeed, AFAICS there is actually no dispute about block placements except for the elements caught up in the group 3 dispute. Apart from WebElements everyone seems to agree that helium is an s element even if most people still do place it over the p element neon. If you have any sources (hopefully within, say, the last 60 years or so) that give unusual block classifications outside La-Ac and Lu-Lr, and do so as if they're explaining something standard rather than going out of their way to propose something new, then please do share them with me. ^_^ Double sharp (talk) 10:37, 15 October 2020 (UTC)

As mentioned above, here's a blocks and categories table. The notes refer to the group 3 situation; the undetermined properties of 113–118; and clarify the nature of the two different kinds of boundary line, firm and fuzzy. Sandbh (talk) 01:04, 18 October 2020 (UTC)