Talk:Block (periodic table)

Merge proposal

 * Section header added (the post was added in 2012 or earlier) -DePiep (talk) 16:45, 8 October 2014 (UTC)

Electron shell, Orbitals, Atomic orbital, Electron configuration and possibly periodic table block should all be merged into a single article, preferably by someone who knows what they are talking about. The Anome

Half of f-block seems to actually be d-block
Curium, for example, is [Rn] 5f7 6d1 7s2. 6d is a higher energy level than 5f, so wouldn't that make Curium, and many others, a d-block element? --Lucent 03:05, 28 June 2007 (UTC)

Successive block sizes
Note that each successive block size is 4 elements larger than the previous block and that in the Janet Periodic table there are 2 each of each successive block. Thus, the blocks go:

S1 =                                                2 S2 =                                                2 P1 =                                          6 P2 =                                          6 D1 =                                  10 D2 =                                  10 F1 =                           14 F2 =                           14 with the remainder of each level in the table being filled with elements in the locations of all the previous blocks. Thus the number of elements in each table level becomes:

L1 =                                                2 L2 =                                                2 L3 =                                                8 L4 =                                                8 L5 =                                               18 L6 =                                               18 L7 =                                               32 L8 =                                               32 The implication of this is that the atom's nucleon accumulation process involves the successive accuummulation of 4 additional nucleons into every 2nd series of elemental additions to the atomic structure.WFPM (talk) 13:46, 16 August 2010 (UTC)

Displayed Extended Periodic Table
Note that in both the displayed Extended and the Janet tables, the first thing that happens after the creation of the 4Be8 Beryllium nucleus is for the accumulation process to finish an accumulation of the deuterons needed for the 6 additional elements up to 10Ne20 Neon, and after that to then to accumulate the nuclei of the elements 11Na22 and 12Mg24. This requires that the third alpha particle nucleus be reconfigured from its alpha particle configuration to some other configuration such as to bond with the previously two accumulated alpha particles.WFPM (talk) 18:53, 19 October 2010 (UTC)

However, as an alternative to the Triple-alpha process proposed by Hans Bethe to explain the creation of the Carbon nucleus, you might consider, as I have, as to the possibility for the double-alpha particle to have successively captured 2 deuteron particles as a means of creating the Carbon nucleus, which is consistent with the indication of the 2 periodic tables, as well as with the reported existence of a quantity of 5Be Beryllium atoms, as is reported in the Nucleosynthesis article.WFPM (talk) 03:14, 20 October 2010 (UTC)

Placement and group/column identification of helium in periodic tables involving blocks
I'm inviting multiple editors here to discuss an issue. If you're not interested or if I've done a bad ping, please forgive me because I've never pinged so much before. Of course, unpinged editors are welcome to contribute. Flying Jazz (talk) 11:50, 7 October 2014 (UTC)

As noted by here and  here at Wikipedia_talk:WikiProject_Elements in comments referring to this edit made by, the current version of the template at Template:Periodic_table_(blocks) which is the central focus of this article seems to identifies helium as a group 2 element in contrast to  which identifies it as a group 18 element. DiPiep created that last image this July in order to replace. Flying Jazz (talk) 11:50, 7 October 2014 (UTC)

Discussion about this particular issue for this particular template and image will take place here on this talk page, not at Project Elements, because of the history of tendentious, unfocused, and long-winded discourse unrelated to encyclopedia building that occurs in that project, the limited number of participants who make useful contributions there about periodic table layouts, and other issues occurring with many WikiProjects in science as I described in an obnoxious rant here. In 2006, changed helium's position in this table from column 18 to column 2 with the edit summary "This table is supposed to represent block structure of the PT, not the IUPAC standard. Helium is in the s-block.". This is involved in the editorial issue I'd like to discuss here. Flying Jazz (talk) 11:50, 7 October 2014 (UTC)

Here are several options for consideration about this particular issue. They are neither mutually exclusive nor exhaustive. Please consider the in your decision. Please make user-focused suggestions.


 * 1) Alter File:Periodic table blocks spdf (32_column).svg to place helium in column 2. DePiep wrote he was adding this option to his a todo list.
 * 2) Alter Template:Periodic_table_(blocks) to place helium in column 18.
 * 3) Remove File:Periodic table blocks spdf (32_column).svg from the article Block_(periodic_table).
 * 4) Alter Template:Periodic_table_(blocks) to replace "2" in the Group labels with "2 with He".
 * 5) Alter Template:Periodic_table_(blocks) to replace "18" in the Group labels with "18 without He".
 * 6) Remove all group numbers (and their associated links) from Template:Periodic_table_(blocks).

I'll be indicating my preferences in a day or two. Feel free to create additional numbered options below. I may also be refactoring this talk page if needed.

We are here to discuss the location of helium in this article, the associated template, and the image mentioned above. If there are other periodic table layout matters to discuss, I hope you find the appropriate talk page outside of a Wikiproject, begin a focused discussion there as I have done here on the single topic at hand, and please invite me and others to contribute. If you'd like to ramble on with unfocused babble about dozens of things at once then please consider doing so on a project talk page where this is the norm.

Please be aware that one or two of the editors I invited here seem to have a long history of taking the talk page posts of others out of context and misrepresenting them. Anything that you write here will likely be strategically and politically gamed in a facile and oblivious way on a Project talk page. These same gaming editors may also read what you write and immediately implement the exact opposite course of action with no further comment. I hope you write your opinions here anyway. Please redirect reverts to this talk page until consensus is reached. In the long run, I still believe that others will read what you wrote and smile at the absurdity of how you were misrepresented. The world needs more smiles, and I still think the best ideas are more likely to be achieved in the long run if they are presented with sufficient clarity and focus to make the gamesmanship of others patently obvious. Flying Jazz (talk) 11:50, 7 October 2014 (UTC)
 * Adding:
 * 7. Removal of Template:Periodic_table_(blocks) from the article.
 * (Added for completeness; no my proposal). -DePiep (talk) 08:13, 8 October 2014 (UTC)
 * 8. Use a Janet Left Step PT to illustrate the PT blocks.
 * (added) -DePiep (talk) 16:25, 8 October 2014 (UTC)


 * I favour option 2. the reason is simple- group 18 are the noble gases, group 2 are the alkaline earths. Helium is definitely in group 18, putting He in group 2 is confusing at the very least. When a table with nice rectangular blocks is widely used in teaching then let us, as an encyclopedia, report on it, in the interim lets use the IUPAC standard with colors to indicate the blocks. The table proposed by Janet is already in the article as an alternative take on the concept. By the way the Soviet block - you young folk will have to get your history books out I'm afraid- was not rectangular, and as far as I know no-one was unduly sleep deprived by the idea. Axiosaurus (talk) 08:53, 9 October 2014 (UTC)


 * Do you mean the Soviet bloc? Flying Jazz (talk) 23:12, 9 October 2014 (UTC)

Framing/focus of the discussion topic & talk page behavior
Two questions: why is the question framed into the limited "the template at Template:Periodic_table_(blocks) which is the central focus of this article", while equally graph File:Periodic table blocks spdf (32_column).svg is present?
 * Why is article text not considered in this topic? Of course, the images/graphs must correspond fully with the text, i.e., not contradict or deviate from. (I expect that the prior question to answer is: which scientific statements do we want to show?). -DePiep (talk) 08:13, 8 October 2014 (UTC)


 * The issue under discussion is framed by the title of this talk page section: "Placement and group/column identification of helium in periodic tables involving blocks." I don't understand the remainder of the first question. I've read it aloud multiple times and tried to understand what I'm being asked. I am sorry. I do understand the second question. Article text is not directly considered in this topic because I chose a topic about a visual layout issue. The answer to "why" is "because that was Flying Jazz's decision." If past history is a guide, some editors who (may or may not) stop by to discuss the layout issue might or might not also improve the article text. It's always good when images/graphs match text. It's always bad when they don't. Flying Jazz (talk) 07:03, 9 October 2014 (UTC)
 * So the section title says it is about the placement (in general) etcetera. That includes, at least, both PTs currently present in the article (there happens to be a PT template and a PT image). All fine so far. Then you write about the template PT only: "which is the central focus". That excludes the image. Why? Or cutting short: following the title, the image belongs in the discussion too, as part of the focus.
 * A priori, and by section title, there is no difference in stature of the two PTs. As a consequence of this, numbered points 2, 3, 4, 5, and 6 are applicable for both PTs, and so should be altered. I already added point #7 to match point #3. -DePiep (talk) 07:47, 9 October 2014 (UTC)
 * I don't understand the phrase "difference in stature" in the context of assisting a reader. Some editors believe that a reader will benefit if an article with periodic table blocks as its main focus shows perfect rectangular blocks with helium in the second column while simultaneously at other locations in the same encyclopedia that emphasize electronic structure without emphasis on them as "blocks," a reader will benefit from seeing a standard table that has helium in the rightmost column as usual. I hold this view, perhaps First Harmonic does, and, based on this recent edit perhaps Dirac66 also has this view. Editors with this opinion would not agree that all options ought to apply uniformly to all the periodic tables under discussion here. Issues and options should be framed to maximize opportunities for editor consensus. I'll be refactoring the talk page beginning with "Two questions" because these posts involve meta-issues about topic framing instead of discussion of the topic itself. Flying Jazz (talk) 13:55, 9 October 2014 (UTC)
 * re "difference in stature" in the context of assisting a reader. - that's not the context (or: in that context, there is no difference). The context I wrote is: why do you treat them different? You only mention the template, not the image. -DePiep (talk) 20:50, 9 October 2014 (UTC)
 * I think I'm starting to understand this now. I called the template "the central focus of the article" because it's big, it catches my eye first, and, to the best of my knowledge, the template seems to be linked to the article in a one-to-one manner while the image, at this moment in time, is used elsewhere in other articles. Flying Jazz (talk) 13:28, 11 October 2014 (UTC)
 * OK. -DePiep (talk) 17:57, 13 October 2014 (UTC)


 * As for editor interaction & talkpage behaviour, including the bad faith paragraph Flying Jazz took time to write here at kickoff, I responded at metawiki. -DePiep (talk) 11:44, 8 October 2014 (UTC)

Pedagogical goals, empiricism and theory
What I would say is this: editors need to remember what the periodic table is FOR in the first place: namely, illustrating periodically recurring properties of elements. Helium is a noble gas. What properties does it share in common with magnesium or radium? What would you be helpfully illustrating by putting it in a diagram which lumps it with the 's block'? What pedagogic goal are you trying to achieve? Remember: empircal observation is our only reality. Theories are just made up to explain observation. Play nice, people :) --feline1 (talk) 13:05, 8 October 2014 (UTC)
 * Apart from having an s2 valence electron configuration, nothing – and even that is suspect because that's a full shell in He's case, while it's nowhere near that for the alkaline earth metals.
 * As for what pedagogical goal is achieved by the block periodic table: goodness knows what, but if the only purpose behind that table is to show what "blocks" the elements belong in, then He could well be argued to belong with its buddies in group 2, and since this table isn't trying to show anything else, then I guess I have to support that. Of course this raises the question: of what value are the blocks for pedagogy? Not very much, I think – if they really meant much of anything then group 3 and 12 wouldn't behave somewhat (for group 12, remove that qualifier) similarly to main group elements, unlike the rest of the d-block. They are probably at best an oversimplification that is helpful when first encountering the periodic table but quickly becomes unhelpful when learning exceptions.
 * But enough people have talked about blocks that I reckon that the concept deserves a place on WP. So the question is: do we want a table illustration that treats blocks as primary, and puts He in group 2; or do we want a table which takes the chemical facts first, and colours the blocks behind it, leaving He in group 18?
 * I think, for a simple illustration of what the blocks are supposed to mean, either would work, but He in group 2 would arguably be graphically clearer. So I would support that, as long as a lot of caveats are mentioned about why this placement doesn't make sense if you even take a glance at the empirical facts, because all we are trying to do is illustrate the blocks. It won't take much to change my mind away from this, though. :-P Double sharp (talk) 15:04, 8 October 2014 (UTC)


 * P.S. My current supports, in order, would be: #7, #1, and #2 (the order of the last two variable; I'll think a bit more). Double sharp (talk) 15:12, 8 October 2014 (UTC)
 * To Double sharp's comment I want to add this note, about the teaching purpose of blocks. It starts explaining nicely (to me at least) the steps in the periodic table, related to shells being filled. It is the main or only base for the steps, another structural feature in the PT. This is shown even better in a Janet Left Step PT (so I add this as possibility #8). -DePiep (talk) 16:25, 8 October 2014 (UTC)


 * Replying to Feline1, I'd say that different articles are intended for different purposes and different sub-audiences who are interested in different things. This means that different articles ought to have different pedagogic goals. With this way of thinking, the people who are at an article on blocks in the periodic table would receive a pedagogically appropriate table layout for their interest in blocks. Such a layout would be a blocky layout with perfect rectangles for each block. I believe that this is what First Harmonic meant in his edit summary ("This table is supposed to represent block structure of the PT, not the IUPAC standard.") People who encounter an image about electronic structure in a different article outside the context of blocks would benefit from seeing helium in the column that corresponds with its group. Because of this view and the advantage of having correct navigational aids, I'm leaning toward options #4&5 together (perhaps with a different wording than "with/without") or option #6, but these aren't strong preferences. In the rest of the encyclopedia, empirical observations based on chemistry should rule, but...the standardized Advanced Placement curriculum in the USA changed recently to include experimental observations from photoelectron spectroscopy as an empirically sound basis for the electron configurations of atoms. Having blocky blocks somewhere on Wikipedia would be nice. Flying Jazz (talk) 19:04, 8 October 2014 (UTC)


 * I am just always wary of the tail wagging the dog re: theory and observation. The reason we came up with a model of electronic structure was to explain empirical observation of properties. Far too often, students learn the theory and say "oh, such-and-such is like this BECAUSE it is the s-block", not "we put this in an s-block because it behaves like this". The s-block is a bunch of elements that have a pretty-much-chemically-inert electron core, and then one or two s-electrons which are readily ionised and "do chemistry". Helium does NOT fit in this category. Its two s-electrons are inert-core electrons, it has no readily ionisable ones which "do chemistry". What sense does it make to put it in an "s-block"? It belongs with the other noble gasses. Any student who thinks (or has been led to believe) that helium belongs in an "s-block" doesn't understand what the s-block is illustrating.
 * Having said all this, if there's some interesting spectroscopic or magnetic behaviour shown by helium which bears direct comparison with (say) magnesium, by all means let's hear it :) --feline1 (talk) 18:52, 9 October 2014 (UTC)


 * I'll reply to your final sentence and work upward through your post, gaining momentum and feigned manic enthusiasm along the way. Head over to http://www.chem.arizona.edu/chemt/Flash/photoelectron.html . I'm not a spectroscopist, let alone a photoelectron spectroscopist (PES), so I'm going to use the word "bumpy" instead of "peak." Click "Dual," "Helium," "Activate 2," and then "Neon." Helium in the left window has a lowest-energy bumpy of height 2. Neon in the right window has a lowest-energy bumpy of height 6. Click "Argon." It also has a lowest energy bumpy of height 6. Now click Beryllium, Magnesium, and Calcium. They have lowest-energy bumpies of height 2. With regard to lowest energy bumpies in a PES, helium has more in common with Be, Mg, and Ca than it has with the noble gases. Carbon and silicon also have lowest energy bumpies of height 2, but, unlike He, Be, Mg, and Ca, carbon and silicon's low-energy bumpies have another low-energy bumpy nearby. Whether this is interesting spectroscopic behavior is a matter of opinion. Because the similarity in spectra are unrelated to the ability to "do chemistry," it strikes me as more physics than chemistry. The interesting thing about PES for me is the number of students in US high schools (probably around 140,000) who began to learn about it in the classroom last year when the vast majority of their teachers had never learned about the instrument in college (because there are so many more interesting and useful instrumental doodads to learn about.) Why have 16-18 year-olds learn about PES in a standardized national curriculum? Because a lot of people, including me, share your views about the critical importance of theory following observation in chemistry pedagogy. In the immortal words of AP Chemistry standard 1.B.1d: "Photoelectron spectroscopy (PES) provides a useful means to engage students in the use of quantum mechanics to interpret spectroscopic data and extract information on atomic structure from such data. In particular, low-resolution PES of atoms provides direct evidence for the shell model." Students and teachers in high schools in these grand states are now trained to say, "We can put this in the s-block because it has that PES spectrum" thus having an obedient dog walking forward with a nice tail. Of course, this evidence has nothing to do with the historical adoption of the shell model, but historical bogosity occurs often when forcing students via bullwhip into the comfortable philosophical abattoir of introductory science pedagogy. All of that is indirectly related to the representation of helium in column 2 in this particular template despite the obvious requirement for other tables to have it in column 18, but I'm not ready yet for a full defense of that position. Maybe if I write "the blocks should be blocky somewhere at Wikipedia" one more time then Dirac66 or First Harmonic or someone else will show up to write something more cogent. Flying Jazz (talk) 23:08, 9 October 2014 (UTC)
 * Well, I take your point. Although I pity the poor students who begin to think the "s-block" is a real thing rather than an "idea". I mean, what do they *do* with helium once they've put it in their s-block? Yes, it has a 1s2 ground state... if they can deduce from that that it's chemically inert and has bizarre physical properties close to absolute zero, good luck to them ;) Any article worth its salt would do well to say clearly "but it behaves nothing like the rest of the s-block elements" :) --feline1 (talk) 11:08, 10 October 2014 (UTC)
 * What do high school students do once they've put helium into the s-block? With regard to applied chemistry, not much that I can see. This is why nearly all periodic tables are and should remain with helium in column 18. But with regard to quantum mechanics, the student has learned something that might be "applied" later (depending on the career path of the student) in the pedagogical sense of applying previous knowledge to new knowledge. At Helium_atom are a bunch of equations describing various approximations to the Schrodinger equation for the two electrons in helium. Periodic table blocks aren't mentioned once in that article as far as I can tell. However, $$ n_1=n_2=1,\, l_1=l_2=0,\, m_1=m_2=0 $$ does make an appearance, as it does in quantum chemistry textbooks that cover similar material. To a quantum mechanics person, the visual representation of "$$ l=0 $$ for all valence electrons" corresponds to the placement of an atom in the s-block of the periodic table from way back in grade school. This is why a teensy number of periodic tables are and (in my view) should remain with helium in column 2. Flying Jazz (talk) 11:32, 11 October 2014 (UTC)

Usage in sources
I seem to have incited quite a discussion here, and I thank Sandbh for pointing it out to me. My original intent was to correct the phrase Helium is placed next to hydrogen instead of on top of neon ... which could be taken to imply that He is always placed next to H by everyone, which clearly everyone in this discussion knows is not true. So I pointed out that there are two ways to organize the periodic table. What I did not do, because it requires a lot of work, is to verify how often the organization by blocks (with He in group 2) is actually used in chemistry books and papers. But since Wikipedia is supposed to reflect usage by sources, I think it would be useful for someone to check this out. If the organization by blocks is frequent, we can quote some of the sources which use it. If it is quite rare, then perhaps we should just delete the statement that He is placed next to H. I think this would be a better way to decide what to do, rather than debate the logical basis of the two ways to organize the table. Dirac66 (talk) 01:51, 10 October 2014 (UTC)
 * Editors here would agree that placement of helium in the second column of the table is quite rare if the entire set of "chemistry books and papers" were considered. So, if we were restricted to having a single periodic table layout everywhere at Wikipedia, helium would never appear in the second column anywhere in the encyclopedia. But I see no reason why such a restriction helps readers who are interested in blocks. A reader who comes to Wikipedia for information about periodic table blocks, not the entirety of chemistry, benefits (in my view) by seeing the table arranged into rectangular blocks with helium in column 2 as is done in some sources. If a literature survey were to be done, sources focusing mostly or entirely on blocks in the periodic table would be consulted, but the results of such a survey would be useless in my view because a good article would show both arrangements (as is done in the current version). Flying Jazz (talk) 13:19, 11 October 2014 (UTC)

Physics books usually show periodic table block s with He above Be [seemingly not in physics textbooks; see below – Sandbh (talk) 10:57, 13 October 2014 (UTC)], as do "many spectroscopic periodic systems" (Scerri 2007, p. 281); chemistry books usually show periodic table blocks with He above Ne. The article could have both versions, like it does now, but with better captions for the image and template. Frex, the image caption could read: "Blocks in the periodic table. Helium is coloured as an s-block element but is positioned above Ne to emphasise its categorisation (in chemistry) as a group 18 element." The template caption might read: "Blocks in the periodic table. In chemistry, helium is a group 18 element but is shown here in the s-block, as a group 2 element, to emphasise its 1s2 electron configuration." Sandbh (talk) 02:32, 10 October 2014 (UTC)
 * Scerri ER 2007, The Periodic Table: Its Story and its Significance, Oxford University Press, Oxford, ISBN 9780195305739
 * My experience with reading Scerri has been that he makes careful and precise choices in word usage. From your first sentence before the semicolon, it is unclear to me whether the opinion that physics books usually show periodic table blocks with He above Be is your opinion or Scerri's opinion, and the context of "periodic table blocks" is also unclear. If you have the text in front of you then please type Scerri's exact words from that page into the talk page here. Include the entire sentence and other sentences nearby if relevant. You will not be violating copyright by doing this, and you will be saving other editors here a trip to the library or to google books or elsewhere. I am writing this because your choice of words about Scerri and the literature was not clear to me. My subjective-and-limited experience has been that the majority of physics books do not show periodic tables with He above Be. However, if and when a physics book is discussing periodic tables in the context of blocks, perhaps the majority do. Scerri's exact words will help me understand his view of the matter. Flying Jazz (talk) 13:19, 11 October 2014 (UTC)
 * Here's the passage from Scerri:
 * "There has been considerable debate within chemistry in recent years as to the placement of the elements hydrogen and helium within the periodic system. For example, hydrogen is similar to the alkali metals in its ability to form single positive ions. However, hydrogen can also form single negative ions, thus suggesting that the element might be placed among the halogens, which also display this type of ion formation. Helium is traditionally regarded as a noble gas in view of its extreme inertness and is thus placed among the other inert gases in group 18 of the periodic system. However, in terms of its electronic configuration, helium has just two outer electrons and might therefore be place among the alkaline earth metals such as magnesium and calcium. Many periodic tables appearing in physics books do just that, as do many spectroscopic periodic systems."
 * I note Scerri uses the broader expression "periodic tables" whereas I used the narrower "periodic table blocks". I regret my inexact use of the word "block", which I have now corrected with a strikeout. Sandbh (talk) 23:39, 11 October 2014 (UTC)
 * Scerri is making careful and precise choices in word usage. What Scerri says is correct, as usual, and it is being misinterpreted or misapplied at Wikipedia, as usual. The phrase many periodic tables appearing in physics books cannot be construed in any way to mean Physics books usually show periodic table... as was done above. Flying Jazz (talk) 15:51, 13 October 2014 (UTC)
 * Your experience is on the mark Flying Jazz. I visited my nearest university library. Of 57 randomly selected physics textbooks 56 had He over Ne. Only one had He over Be but this also showed (in the same table) He over Ne, albeit inside a dotted line box rather than a solid line box. I now don't know what Scerri had in mind. I wasn't looking too closely but when these text books were talking about electron configurations they illustrated that in a plain line-by-line table starting with H then proceeding down the page with He, Li, Be etc. I don't remember seeing any of their periodic tables showing s, p, d, f blocks. That seems to be a chemistry textbook thing. He over Ne appears to rule. Sandbh (talk) 10:57, 13 October 2014 (UTC)
 * A gold star for all this library work! Or perhaps a lanthanum (Z=57) star for 57 books. So perhaps we should just say that helium is normally placed over neon because of its chemical inertness, even though this might suggest that it is in the p-block. Dirac66 (talk) 11:32, 13 October 2014 (UTC)
 * As a leading researcher in the history and philosophy of chemistry, what Scerri might have "had in mind" can be approached by reading and understanding my discussion with feline1 above. In addition to choosing the word "many" instead of "usual," Scerri also chose the word books instead of textbooks. I don't agree that this particular editorial decision is aided in any way by attempting informal or formal literature surveys to confirm or deny a mischaracterization of a simple, single statement by one author. It would have been better to have not mischaracterized the author's words in the first place. Flying Jazz (talk) 16:15, 13 October 2014 (UTC)

Omitting j
How is the lack of a j meaningful to such a small periodic table. If the blocks continue at the rate suggested by the Aufbau principle, the first element of the j-block won't be until atomic number 561, which is much too large to talk about right now. Any arguments that a chemical element with an atomic number of 561 exists?? Georgia guy (talk) 15:04, 10 August 2015 (UTC)


 * The order s,p,d,f,g,h,i,k,... for l = 0,1,2,3,4,5,6,7, ... was originally established for atomic orbitals, which can be occupied in excited atomic states from which spectroscopic transitions are in fact observed. It is true that orbitals with l=7 (which by convention are k rather than j) will not be occupied in the ground state of any element to be discovered in the foreseeable future if ever, and therefore the decision that the blocks after the g-block will be h-block, i-block, k-block, ... will probably have never any practical effect. Let's say it is a decision which was made for consistency just in case of any very unlikely discoveries. Dirac66 (talk) 21:11, 10 August 2015 (UTC)
 * OK, now I want to know why the j gets omitted. Sandbh (talk) 11:03, 11 August 2015 (UTC)
 * I vaguely remember the professor who taught me this years ago saying that j was omitted because it is used as a quantum number for total angular momentum (orbital plus spin). But then one would think that l would be omitted also as it is orbital angular momentum, and in fact it is not omitted. We need a source for that question.
 * More important for this article is Georgia guy's implicit question of whether the omission of j is relevant to this article. In fact the article Spectroscopic notation has more detail in the context of spectroscopy (rather than the periodic table) which makes more sense. So I will modify this article to just mention s, p, d, f, g (as we may soon get to the g-block elements), and say that follows spectroscopic notation with a link to the other article. Dirac66 (talk) 13:39, 11 August 2015 (UTC)
 * According to https://books.google.com/books?id=QbQJAgAAQBAJ&pg=PA106, j was omitted because some languages don't distinguish between i and j. More about that is at https://en.wikipedia.org/wiki/J#Use_in_other_languages . However, like Dirac wrote, I don't think this discussion is relevant to this article, and it was a good thing to remove mention of anything beyond g from this article. Flying Jazz (talk) 14:24, 16 August 2015 (UTC)
 * Thank you for the answer and source. Not relevant to this article, but I will add the information to the article on Spectroscopic notation which does go beyond g. Dirac66 (talk) 18:02, 16 August 2015 (UTC)

Comments
Just my first impressions:
 * Lede: "adjacent groups" (1st sentence) seems less defining and incorrect c/w the statement "same orbit".
 * I'd expect Janets Left Step periodic table in here. Quite a more simple/intuitive way to show buildup of blocks, still within periodic law.
 * I'd expect any block description to be about block-related properties. Examplary p-block lists all categories contained, but why a single block can have this variety is untouched. If it is untrelated, then we can omit it?
 * I see no need or use for an 18-column PT. Why add another feature that first must be explained, before one can get to the topic?
 * -DePiep (talk) 18:55, 20 January 2016 (UTC)

chemistry
What happens when na2o2 is dissolved in h20 After khan (talk) 07:28, 26 January 2016 (UTC)

some general comments
As someone with only a modest study of chemistry at the college level, I found this page fascinating and highly readable for beginners. However, there are descriptors that seem like weasel words, specifically "rare" which I assume refers to earth's crust. In that case, Boron ranks as #41, hardly rare: Abundance_of_elements_in_Earth%27s_crust. If we're talking about the entire earth, the solar system, or even bigger natural entities, then this page is worth referring to: Abundance_of_the_chemical_elements

Another comment I offer is that the examples given for applications of various elements are predominantly metallurgical or mechanical, which seems arbitrary if not an unintentional POV. For example, in p block metalloids, there is no mention of biology for antimony, carbon, phosphorus, or selenium.

And the Metalloids subsection is completely devoid of sources. Martindo (talk) 01:51, 17 November 2018 (UTC)

Definition of a block
Surprisingly enough, this is sometimes (and given my difficulty in finding a definition, perhaps often) not defined in the first place. Gary Wulfsberg, for example, starts by listing what elements are in the s, p, d, f, and g blocks in Principles of Descriptive Inorganic Chemistry (p. 4), but does not seem to actually say what a "block" is. Sometimes we see references to simple filling of the respective orbital (s, p, d, or f), or where the valence electrons happen to be. (Which incidentally, never mind the howler on that page where they claim that the valence electrons of the p elements are in the p orbitals, forgetting hybridisation and the fact that it's an octet and not a sextet rule, implies upon correction in particular that helium is an s-block element regardless of where we happen to put it, since this defines blocks in terms of the elements rather than the table. And also, it clearly points to La and Ac as the true f elements instead of Lu and Lr: the latter have core f electrons, but the former two can have valence f electrons in some chemical environments, just like Th!) Differentiating electrons are not always a part of the definition of what a block is, despite what the current lede suggests! Which is expected as chemistry is based on more than just ground-state configurations, and there is no good definition of such a thing: what is the differentiating electron between ground-state vanadium [Ar]3d34s2 and chromium [Ar]3d54s1? The question is not well-defined, as there is more than one! Double sharp (talk) 04:43, 27 March 2020 (UTC)
 * Replaced by a proper definition from Jensen (10.1007/s10698-015-9216-1). Double sharp (talk) 13:03, 28 March 2020 (UTC)

P.S. Have half the mind to get rid of the Stewart quote, which is firstly a primary-source quote for something that is standard and should not need such things; secondly talks about blocks based on chemical similarities, when it is about electronic structure; and thirdly just wrong ("metals with multiple oxidation states" would take in almost everything outside the s-block; "metals so similar that their separation is problematic" is only really true for 4f elements, not true at all for 5f elements, and from a chemical perspective perhaps just as true of Zr vs Hf which is not in the f-block at all). Double sharp (talk) 13:19, 8 February 2021 (UTC)

ENGVAR to be established
The article needs the WP:ENGVAR to be determined. Currently is has both "-ize" and "-ise". Per MOS, earliest applied engvar rules. -DePiep (talk) 07:53, 30 July 2021 (UTC)
 * I don't see a problem here. The conflicting "-ize" and "-ise" both appear only in quotations, which always preserve the exact wording and spelling of the original author. In the article text, the only distinction I see is the presence of colour and analogue, which are British (en-GB) or Commonwealth spellings. ComplexRational (talk) 13:46, 30 July 2021 (UTC)
 * OK. I did not do any research yet. I was triggered by this edit. -DePiep (talk) 21:40, 30 July 2021 (UTC)

Clarification of Symmetry
The sentence "The four blocks can be rearranged such that they fit, equidistantly spaced, inside a regular tetrahedron." is probably referring to Tsimmerman’s tetrahedron, as described in (currently reference 3 on the page) figure 1 Charles haynes (talk) 13:29, 2 October 2021 (UTC)