User talk:MadeOfAtoms

A belated welcome!


Here's wishing you a belated welcome to Wikipedia, MadeOfAtoms! I see that you've already been around a while and wanted to thank you for your contributions. Though you seem to have been successful in finding your way around, you may still benefit from following some of the links below, which help editors get the most out of Wikipedia:


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I hope you enjoy editing here and being a Wikipedian! Again, welcome! Polyamorph (talk) 10:10, 15 June 2021 (UTC)
 * Thank you kindly Polyamorph . The short list of links is very helpful and the cookies are excellent! --MadeOfAtoms (talk) 20:01, 15 June 2021 (UTC)

Keep up the good work
Keep up the good work. All articles benefit from a new set of eyes, especially longer ones (articles, that is). Agreed: references to answers.com and many related "regurgitators" should be removed.--Smokefoot (talk) 13:09, 29 July 2021 (UTC)
 * Your encouragement and guidance are much appreciated. Thank you also for being a tireless educator and for the inside scoop on fluoride. I have wondered who's been remote-controlling my thoughts lately and figured it was space aliens using 5G to control the nanobots injected with the vaccine, but now I know it was the toothpaste all along. –MadeOfAtoms (talk) 21:40, 29 July 2021 (UTC)
 * I cannot respond fully since the introduction of magnetic nano-drones into my blood steam as part of my so-called "COVID vaccine."--Smokefoot (talk) 02:29, 2 August 2021 (UTC)
 * My condolences, you're not alone. A tin-foil hat works for me — keeps the thoughts echoing inside, remote-control rays out. (Beware of foil that is not actually tin, as aren't the cans and the ears. And why no company called Sncoa — acquired and Snuffed out by Alcoa of at. no. 13? Note the "missing" floor 13 at Trump Tower, like it doesn't exist! Triskaidekaphobia they shout, as if that's a real excuse instead of something the cat typed. Note that the Br-itish, Au-ssies and In-dians spell Aluminum wrong on purpose...but why?? I'll tell you: it evades search engine detection (smart!) and I like that they make an honest effort to speak English. Maps apps conceal all the ways to drive there from the Americas...a secret blockade?) Look both ways, never sleep, and take good care. –MadeOfAtoms (talk) 04:44, 2 August 2021 (UTC)

How to repair any electronic device
(This represents my experience only, and it is not entirely serious.)


 * 1) Is it plugged in?
 * 2) Is it turned on?
 * 3) Did you reboot it?
 * 4) Did you flip every switch and wiggle every connector?
 * 5) Does the fan spin if you vacuum the lint out of it?
 * 6) What about the fuse?
 * 7) Still not working? Bummer, it's broken. Take a deep breath.
 * 8) Open it up and look inside.
 * 9) *Tip: Save most of the screws for later, in case you fix it.
 * 10) How's the battery for the CMOS memory holding up?
 * Tip: You should have saved a copy of the firmware last time this happened.
 * 1) Any charred components? Stains from smoke or flame? Rodents?
 * 2) *Yes: Well, there's your problem.
 * 3) Bright flashing sparks or sharp “tasing” sensation?
 * 4) *Yes: Unplug it right away or put on goggles and shoes. Safety first!
 * 5) Power supply outputs okay?
 * No: Check and repair the:
 * 1) Power switch
 * 2) Bridge rectifier
 * 3) Electrolytic capacitors
 * 4) Voltage regulator or power transistors
 * 5) Still not working? Uh-oh, maybe it's really broken.
 * 6) Get out some oscilloscopes, a signal generator and a spectrum analyzer to show it that you're entirely serious.
 * 7) Do you have the schematics?
 * No: Reverse engineer the whole thing and draw up your own schematics:
 * 1) **Identify every component and trace out every wire.
 * Tip: A four-probe ohm meter can detect the branching pattern, and microvolt drops on the power traces tell you where the current is flowing.
 * Tip: Every time your schematic starts to run off the page, tape another piece of paper to the edge.
 * 1) **Find better schematics that were posted on the web by a benevolent grad student half-way around the world.
 * Tip: Try following the previous instruction earlier.
 * 1) Make it function as shown in the schematics.
 * Tip: You may need to replace “parts”. All transistors are the same so don't worry about NPN versus PNP, and those indecipherable “specs” are just for marketing. When you power it up, wrong ones weed themselves out with a “bang”.
 * Tip: Same story for op-amps. The really hot ones are fine; they're just plugged in backwards.
 * Tip: Remember that a resistor that says “1000” really means “100”. The zero at the end means that there is no zero at the end. I kid you not. If you actually want 1000 Ohms, don't even bother looking, as they were used up long ago. Use nine hundred whatever just like everyone else does.
 * 1) *Tip: Some small parts tend to leave the universe for a time. The ones that return often choose a pant cuff or neighboring room.
 * 2) Screw it all back together. Then try this trick: turn it over and shake it to hear some of the screws you thought you lost.
 * 3) Maybe it works now?
 * No: How much is a refurbished one on eBay?
 * 1) Voilà, problem fixed!

–MadeOfAtoms (talk) 09:50, 5 August 2021 (UTC)

Enantiomer
Thanks for the efforts of taming some of our many articles. I have long been taught, by stern organic colleagues, that there is no such thing as a chiral center because the concept pretends that only part of the molecule is chiral. And even if there were such a thing, it would be called a stereogenic center, a term that directs to Stereocenter. On that note, is there a map of all of our articles on chirality?--Smokefoot (talk) 02:31, 17 August 2021 (UTC)


 * Thank you Smokefoot, it's really good to hear from you. As a interested non-chemist, I hope to do my part to build on your years of work in making these articles clear and readable. I welcome any help and corrections along the way, from you and other chemists, to keep my edits accurate and not too funny-sounding.


 * The only map of chirality-related chemistry articles I know of are the navbox templates: Template:Asymmetric synthesis and Template:Navbox stereochemistry. Molecular symmetry and Prochirality should be on the list too.


 * Maybe I stumbled into a peeve of your stern colleagues when I recently changed a section name in Enantiomers to "chirality centers". I believe that chirality centers, point chirality, etc. can be a well-defined and useful concepts, though the definitions and use are tricky. I struggled for the right terms since stereocenter refers equally to any kind of stereoisomer including cis/trans ones. It is folly to assign a "point" in space that makes an asymmetric object so. But the concept of examining local symmetry such as generalized asymmetric carbon is fruitful. Your thoughts and suggestions are most welcome, especially about how to refer to "chirality centers". The related and tricky idea of "chiral" groups and ligands also needs some further explanations. –MadeOfAtoms (talk) 09:51, 17 August 2021 (UTC)

Cis-trans isomerism
Please elaborate reasons for this reversion. I would like to know the difference between configurational isomerism and spatial orientation of molecules. CrafterNova (talk) 13:08, 11 January 2022 (UTC)
 * Hi, in cis–trans isomerism (or any kind of isomerism) the spatial orientation of the molecules doesn't matter: a cis-1,2-dichloroethene molecule is a different configurational isomer than a trans-1,2-dichloroethene molecule no matter how they are rotated in space. One might say that in different configurational isomers, the functional groups have different relative orientations in space, though I'm not sure that would be a clear explanation. The important thing is the geometry of the molecule, not how the whole molecule is oriented. In any case, thank you for all your work improving Wikipedia. –MadeOfAtoms (talk) 07:21, 12 January 2022 (UTC)

I see you mentioned about spatial arrangement in the article and in its short description. So instead of reverting all changes made by any user in one or more edits, most commonly it's better to edit those revisions, make corrections and inform user(s) accordingly. Also, we need adequate points making differences between chemoselectivity and stereoselective, or else these 2 articles should be merged into a single article. &mdash; CrafterNova talk 05:27, 12 January 2022 (UTC)) 16:15, 12 January 2022 (UTC)
 * I agree that it is desirable (and more friendly) to improve rather than revert other users' work. In this case I reverted your brief edit because I believe it was not accurate, as I explained in the edit summary.
 * I haven't studied the articles on chemoselectivity and stereoselectivity enough to hold an opinion about merging, so I will leave that up to you and other editors. –MadeOfAtoms (talk) 01:55, 13 January 2022 (UTC)

Merger of Alkane stereochemistry into Conformational isomerism
Hi, there has been a recent objection to the merger of Alkane stereochemistry into Conformational isomerism so I was wondering if you would be willing to rejoin the discussion again since the consensus was made a year ago but I want to ensure that this current objection is heard by the original participants of the discussion before I merge and remove this from the backlog. Thanks! -Karthanitesh (talk) 00:57, 19 January 2022 (UTC)

Regarding your comment about the speed bump after the s-block
Since you mentioned that at the Talk:Periodic table RFC: it's not remotely standard (even though a bunch of serious voices like Henry Bent and Eric Scerri like it), but you might be interested in Charles Janet's unorthodox way to deal with that. He put the s-block on the far right of his table (1928), rather than the far left.

Double sharp (talk) 00:02, 25 January 2022 (UTC)


 * Thanks, this is awesome to see! I was pondering exactly this arrangement yesterday, and fretting about what to do with H and He, wanting to treat them as a halogen and a noble gas by moving their little block, but that would wreck other properties. I am really glad to learn that this form's been considered seriously and thank you for going out of your way to share it. Its elegant structure makes it inevitable that helium would be sent back home to its s-block column. Compromises must be made. The traditional group numbers 1–18 also need to be revamped here. Using -16 through +1 could work. No wait — just use the orbital and occupation (call them "Madelung's suggestion") which is already there as column headings...brilliant! –MadeOfAtoms (talk) 08:54, 25 January 2022 (UTC)
 * Glad you like it, it's one of my favourites. :)
 * Janet displayed three different versions in his paper describing his periodic system; the first one indeed had H over F and He over Ne. The second had He over Ne and H outside the table altogether. But the third one has H over Li and He over Be as pictured, and he decided to adopt it, despite some concern that such a placement of helium would not be accepted. :) Double sharp (talk) 10:09, 25 January 2022 (UTC)

Sulfur trioxide
Hi, I wanted to explain that I provided those two references because my point was that the trimer is only observed under specific experimental conditions. Those two papers actually agree with one another. But I didn’t notice that the trimer was already mentioned below, and the revert made sense. Still, I think that the article should explain that under conditions of low vapor density only the monomer is observed, whereas the trimer can be seen at higher density. If you don’t mind, I’d like to have a try at that. KeeYou Flib (talk) 21:48, 2 February 2022 (UTC)
 * Hi, I was just in the process of rearranging to avoid this confusingly split treatment of the trimer when I saw this message from you. I'll quit and let you work on it. Feel free to revert what I have just done if you prefer a different approach. –MadeOfAtoms (talk) 22:09, 2 February 2022 (UTC)

No, this is good! Keep going by all means. KeeYou Flib (talk) 22:11, 2 February 2022 (UTC)
 * Thanks KeeYou Flib, I'm all done for now so please have at it. –MadeOfAtoms (talk) 22:19, 2 February 2022 (UTC)

Please review paragraph in computer program
Your edits in silicon made me think you could help my accuracy in the computer program article. I synthesized different sources to write the MOS transistor section here: Computer_program. Could you check it for accuracy, please? Timhowardriley (talk) 11:35, 8 February 2022 (UTC)
 * Hi, thanks for working to make computer program accurate and well sourced. For the section about History of VLSI, my impression is that it would help a lot to explain how development of MOS and VLSI have influenced computer programs, since that is the title subject of the article. Anything that lacks a clear connection to computer programs could be omitted or moved to appropriate hardware or history articles. The statement about microcode being needed to oversee burning of ROMs sounds unlikely to me, so please check. I believe that the main practice is to store the microcode itself in the ROM. I'm not an expert in these subjects but if I spot inaccuracies I'll make edits or let you know. –MadeOfAtoms (talk) 06:58, 10 February 2022 (UTC)
 * Thanks for the look and advice.
 * * Since you didn't suggest corrections for the silicate minerals --> Siemens process --> polysilicon rods --> Czochralski process -->  monocrystalline silicon, boule crystal --> ... --> MOS transistor chain, I'm now confident of my secondary research.
 * * The external microcode to burn ROMs occurred in the 1960s, according to the source. Yes, microcode is now stored on the same chip.
 * * Yes, hardware improvements enabled software improvements. Your suggestion is inspiring me to add a new subsection in the history section titled "Modern programming environment". It will provide a preview of material presented in the rest of the article. Timhowardriley (talk) 13:40, 10 February 2022 (UTC)

Maestro2016
Hey just to let you know, the main contributor to Mosfet and Mohamed M. Atalla has been banned for being sock puppet of Jagged 85, a well known vandal []. You can see Requests for comment/Jagged 85 and Wikipedia_talk:Requests_for_comment/Jagged_85 for more info about him. I suspected he was Jagged 85 sock puppet but now it is established. If you want to join clean up that would be great. I would start clean up soon. The amount of erroneous information is enormous, so some articles probably had to be stubbed just like in previous Jagged 85 cleanup, but we'll see. DMKR2005 (talk) 20:57, 27 June 2022 (UTC)
 * Thanks for the update and perspective. I really appreciate your work on this problem. I saw bulky inappropriate material on a few dozen articles but had no idea of the scope of the problem. I'd be glad to help clean up on the science and tech articles. Where possible it would be better for the cuts to be done by an editor who is already familiar with the history and has sources on hand, to retain any well-justified material. Otherwise, it shouldn't fall on us to assume that anything is valid after the history of malfeasance, so removing the problem material en masse is a good start, even if some good stuff gets temporarily cut. Let me know if you recommend a different approach. –MadeOfAtoms (talk) 17:09, 29 June 2022 (UTC)
 * Thanks, I think most articles can be cleaned up, but in general if you see exceptional claim backed up by hard-to check-source, just delete it, as it was one of Jagged 85 favorite tactics to introduce disinformation. However I think Mosfet article probably should be stabbed, as it would take too much time to clean up. But we'll see. I'll start a discussion on MOSFET talk page soon, and will list my problems with article. Hopefully other users will jump in and we'll figure out what to do. DMKR2005 (talk) 21:23, 29 June 2022 (UTC)

MOSFET
Hey, just wanna let you know I started discussion here about what to do with MOSFET and MOSFET applications articles. Feel free to chip in. DMKR2005 (talk) 20:23, 2 July 2022 (UTC)

Your expertise needed
Hello, MadeOfAtoms. You don't know me, but I stumbled on some edits by, who I also don't know, involving "de-orphaning" articles. I know nothing about that process, but discovered that you and another editor educated Herravondure on May 2 about those types of edits. But I can see that since then, there have been many edit summaries showing "Successfully de-orphaned!", not to mention the hundreds done prior to your inquiries on the editior's talk page. I just wanted to see if you could review some of Herravondure's de-orphaning edits to determine if they're being done as you instructed. I thought I should let you know in order to prevent an ongoing problem. Thanks much. Stoarm (talk) 13:55, 14 August 2022 (UTC)
 * Hi, I'm not a fan of rote rule-following such as mass de-orphaning by Herravondure, and would rather that editors make thoughful improvements on each article. Even though they are not doing much to finding related articles and add appropriate links as recommended in WP:ORPHAN, I don't see a great deal of harm here. My perception is that the utility of the orphan tag is to serve as a comment to editors that the article needs to be better linked-to (or deleted), something that must have been more urgent in the early days of Wikipedia. I concentrate mostly on science articles and don't see many cases to complain about lately, but will speak up or edit for anything that looks like a problem. If this mass de-orphaning bothers you and you perceive that it is doing harm then I encourage you to put a note on Herravondure's talk page with an explanation and your suggestions. Thanks for working to improve things. –MadeOfAtoms (talk) 07:17, 15 August 2022 (UTC)
 * Hello, again. I received a very similar response from the other editor who addressed Herravondure about the de-orphaning. What you said makes total sense. Those edits don't bother me. I just wanted to make sure this wasn't an issue that could create significant problems. Thanks for your response and kind words, and all your great contributions to this project. Stoarm (talk) 16:25, 15 August 2022 (UTC)

Starbox
This might amuse you, if you haven't discovered it already. Looking at the Sirius article's source, I couldn't see the infobox distance. Perhaps it was looking it up somewhere, I'd have to check the template. Eventually I read in Starbox astrometry (!) that "if dist_ly and dist_pc are omitted, but parallax is present, then the object's distance will be computed from parallax and, if present, p_error" and now I am properly impressed. NebY (talk) 00:46, 21 November 2022 (UTC)
 * Thanks, I had not noticed this and am indeed impressed that the astrometrists (or maybe it's astrometrologists, but definitely not astrometeorologists) have it this organized. And severely impressed that it is possible to use parallax to make reliable distance measurements up to 5,000 parsecs (16,000 ly). –MadeOfAtoms (talk) 08:05, 21 November 2022 (UTC)
 * Yes indeed. We've come a long way – the "Galaxy" entry in The British Encyclopedia, 1933 (within living memory though not mine) ends "Some astronomers believe that the spiral nebulae, of which the Great Nebula in Andromeda is in our view the largest, are external galaxies, and that our galaxy seen from one of them would present merely the appearance of a spiral nebula." NebY (talk) 16:16, 21 November 2022 (UTC)
 * I wish we could be around to see our imminent slow-motion collision with Andromeda, but there is plenty to astonish us just in our lifetimes. Maybe we'll get to see the reflection of our own galaxy as it was a billion years ago by peering into a conveniently located gravitational mirror. –MadeOfAtoms (talk) 10:47, 23 November 2022 (UTC)

Re your thanks
It may interest you that Ba I has [Xe]6s15d1 at lower energy than [Xe]6s16p1, and that (n−1)d AOs are actually involved in MX2 (M = Ca, Sr, Ba). And at least one paper already calls barium an honorary transition metal. :)

I doubt anyone has investigated Fr or Ra. Though, on energetic grounds, Rb and Cs are also suspicious. Double sharp (talk) 11:38, 26 December 2022 (UTC)


 * Thanks for updating and simplifying Transition metal, and for the perspective here on these group 2 members that behave like transition metals. Clearly the definition of TM varies and most of the  definitions have grey areas (and even "d-block" is unclear though I'm glad to see the La-vs-Lu spat resolving). The Definition section explains the complexity well now, but I hoped the lede could express this with the alternative definition about having d orbitals involved in chemistry; that would be in line with a common "practical" meaning of TM and the 1997 Gold Book definition, which specifies d-orbital chemistry but punts on a specifying exactly which elements. (In my imagination, I can just see a bunch of chemistry geezers agreeing to leave it vague after a long day of haggling over the definition, so they can just go home. I'm curious how the process actually worked.)  I think the lede still needs an adjustment where it now says They all can use d orbitals as valence orbitals to form chemical bonds, when group 12 doesn't do that (excluding rare and controversial observations) so that's incompatible with the strict "d-block" definition. Maybe say All except group 12 can use d orbitals...? Thoughts?  –MadeOfAtoms (talk) 23:06, 27 December 2022 (UTC)
 * Zn 3d and the congeners have already been found as bonding AOs in quite normal compounds like ZnF2, see refs 22 to 24. That's been known for Zn since 1971, so it's not particularly new or controversial. The issue is rather that oxidation states in which the (n−1)d electrons are formally lost in the ion are not known. But then again, did you know that the ground state of Pu6+ is [Hg]6p55f3? That doesn't mean that PuVI in actual bonding has any 6p involvement, though. So my impression is that the requirement for ions is one of those simplifications that were thought to be the last word at some point, and still get used in school texts, but now we know more than that. (After all, there is no such thing as a truly ionic bond, not even Cs–F. The cation will always attract some electron density back to itself.) Maybe this kind of thing also explains why the IUPAC definition has been changing: in the Gold Book (I think it's based on the 3rd edition of the Red Book) it wants incomplete d-shells in the ion, in the 2005 Red Book it says groups 3 to 12 (though you can exclude 12), and in the 2011 Principles of Chemical Nomenclature it just says 3 to 12 without any provisions for excluding anybody. Though being a fly on the wall in their meetings would've been interesting. :)
 * But since f-elements also have d valence orbitals, I decided to delete the sentence from the lede as confusing even if not wrong. Probably Cs through Hg all have some kind of 5d involvement, but calling them all transition elements is a bit much, and I don't want to give that impression. :)
 * La vs Lu being mentioned in two different IUPAC reports is a relief, yes. Now if only the textbooks would pay attention to it more often (or at least crack open Landafshitz where it is mentioned that Lu is not really a rare earth).
 * Come to think of it, I should probably add something about the Ca-Sr-Ba triad, since "honorary transition metal" has already appeared in the literature. At the moment "transition metal" and "d-block" are the same thing per the latest statements from IUPAC, but who knows what people will decide later based on those carbonyls. And here's another recent paper. Double sharp (talk) 03:51, 28 December 2022 (UTC)
 * Your reasons make sense for changing "They are the elements that can use d orbitals ...". Good point about group 12 chemistry involving 3 d orbitals; I should have read that paragraph carefully. Agreed that too much meaning is attributed to oxidation states, which are often only remotely related to the named ion. Also, you make a good case for adding a subsection about the esteemed honorary TMs. Cheers, –MadeOfAtoms (talk) 07:32, 28 December 2022 (UTC)
 * Great to hear that! :) I've added a paragraph about Ca, Sr, and Ba as honorary transition metals. (Too bad about Ra, if only someone had looked at it. It probably would be one too.)
 * For some further fun: under pressure caesium becomes a 5d-band metal (here's two papers from the 1970s). There's some question about whether it becomes a 4f-band metal at even higher pressure (another 1970s paper saying yes, a 1980s paper saying probably not). I haven't seen much recent work on this, but perhaps given the properties of caesium metal I should not be surprised. I'm still convinced it will turn out to be another "honorary" transition metal even at standard pressure, but I'm still looking through the literature. In general, the electronic structures of heavy alkali metals K, Rb, Cs is something I'm quite interested in at the moment. :) Double sharp (talk) 07:43, 28 December 2022 (UTC)
 * Yeah, all I find is this 2003 calculation for caesium 5d. But I am not aware that the molecule in question has been synthesised, so K-Rb-Cs will have to wait to be honoured (if they turn out to merit the honour). :) Double sharp (talk) 08:01, 28 December 2022 (UTC)
 * P.S. Do you have access to this? Because I don't. :( Double sharp (talk) 07:53, 28 December 2022 (UTC)
 * Good luck on your Cs 5d publication! –MadeOfAtoms (talk) 09:53, 28 December 2022 (UTC)
 * Thanks! Caesium will have to cooperate (also some other orbitals are of interest), but I suspect it will. If not, then I've learned something as well. I expect less from K and Rb; Fr should be intermediate between Rb and Cs like it usually is. Double sharp (talk) 15:40, 29 December 2022 (UTC)

A postscript for some closure: I think I was wrong about Cs 5d at standard conditions. (Under pressure it is possible, but that is a different story, considering that then even Xe 5d is possible too IIRC.) Well, it explains why Pyykkö's paper has been cited a lot for Ca-Sr-Ba as honorary transition metals, but the possibility for Cs has been mostly ignored since then in the literature. It's just too unlikely to happen when [Xe]7s < [Xe]5d in a bare neutral Cs atom. :(

Oh well, I learned something indeed. And there's always Cs 5p to hope for. (Even if not, Fr 6p should be more likely. But okay, given the half-life, that is not so much "hoping" as "dreaming". :D) Double sharp (talk) 18:01, 18 January 2024 (UTC)


 * Condolences for cesium's deserted 5d. Your persistence in exploring outside the box will surely turn up more interesting surprises. –MadeOfAtoms (talk) 19:07, 19 January 2024 (UTC)
 * On weird things happening to alkali metals under pressure: some calculations on a high-pressure electride phase of Na came out a few months ago.
 * (My personal opinion is that the periodic table is a human-scale-pressure thing. Beyond that, don't be too surprised if all sorts of delightful weirdness happens. Maybe that suggests that there's no need to worry about 8th-row elements' placement; well, on the human scale, Z cannot exceed 100, so don't be surprised if delightful weirdness contradicting periodicity happens past that. It's all still part of the big chemistry family, nonetheless – though I personally don't mind if physicists want a dual-administration regime; after all, the last hurrah of chemically rather than physically identifying new elements was mendelevium in 1955. :D) Double sharp (talk) 16:59, 1 February 2024 (UTC)

Good article reassessment for Manganese
Manganese has been nominated for a good article reassessment. If you are interested in the discussion, please participate by adding your comments to the reassessment page. If concerns are not addressed during the review period, the good article status may be removed from the article.  141 Pr  09:07, 4 February 2023 (UTC)

Regarding Aufbau violations
I agree it is in the wrong place on the Cr article, but the funny thing is, it is kind of explaining the right thing in general. Because in fact 3d has lower energy than 4s in a Cr atom; knowing that, the natural question is indeed really "so why is 4s filled at all", and not "why isn't 4s completely filled"? The Aufbau is often stated sloppily, but really 4s only comes before 3d in the context of "add a proton and an electron, that's the next element" starting from hydrogen. If you add electrons successively to a bare nucleus, then it is a different story.

In individual atoms, interelectronic repulsion explains 4s occupancy. In compounds this can change. When atoms are positively charged, increased attraction to the nucleus wins as screening is decreased, so Fe2+ (also Cr-like) is 3d64s0. A few times +2 is not quite enough to fix things, but normally it is. The exceptions are La, Gd, Lu, Ac, Th, Pa, and probably 6d metals Lr–Cn which due to relativistic effects truly do have 7s < 6d even in the atom. Truly strange things will probably start to happen at Z > 120 when 5g becomes involved, but we'll need more detailed calculations. Anyway, it's not like it'll be of much practical relevance for a long while. ;)

The whole thing is kind of silly though, because the levels of different configurations overlap, e.g. the lowest-energy state of a Ni atom is a 3d84s2 one, but the average energy of 3d94s1 states is lower than the average of 3d84s2 states. And the fact that 7s < 6d for 6d metals doesn't seem to make any difference compared to 6s > 5d for 5d metals; Lr-Hs behave like congeners of Lu-Os anyway. Personally, I'd rather not emphasise it, and simply follow Feynman's lectures in saying that transition elements have multiple configurations close to each other and that the atom's environment plays a large role. Much more correct than all the teachers asking pupils to remember Cr and Cu. :) Double sharp (talk) 03:20, 11 January 2024 (UTC)


 * Hi, I thoroughly agree with your comments. I think it would be helpful to add more discussion of the physical reasoning for how the Madelung ordering comes about, and why there are exceptions. It could extend the Madelung ordering part of the article on the Aufbau principle and a few related articles. Neither of us wants to belabor the exceptions too much for reasons you described, but it would be good to have a description of each Madelung exception in articles for some exceptional elements, such as Cr and Cu, if it is possible to be reasonably brief, broadly understandable, and accurate enough, though that sounds like a tall order. I agree that focusing on it is somewhat silly because the different configurations are close enough in energy that they get reordered (or mixed into superposition) when in a chemical bonding environment, but I think it's still worth trying to explain the main reasons for Madelung and for exceptions. I had intended to add something for Cr saying that 4s13d5 ground state is close in energy to the 4s23d4 specified by Madelung, so they tend to switch or mix; but according the the NIST database of atomic levels (great resource!) the first 4s23d4 level is 0.96 eV higher in energy, which is a third the energy of a chemical bond, so the difference is not so subtle. The difference in the case of V, for example, is much smaller (0.26 eV and of the opposite sign) so why should we consider the difference small for Cr? That's my take on it, but sources such as the Walraven lecture notes on atomic physics do describe the difference for Cr as small: Anomalies occur in the periodic table when two confgurations have approximately the same energy. This holds for instance for the [Ar]3d54s1 and [Ar]3d44s2 confgurations of chromium (Cr) ... and for copper (Cu) ...


 * The general tendency to form half- or fully-filled subshells deserves more coverage. Aufbau principle mentions it but doesn't say why. It seems intuitively attractive that the electrons can get out of each other's way by filling out the subshell with spherical symmetry as in d5 and d10 cases. But that says little about the relative energy of the 5s and 3d and why it shifts. For example, I don't have a proper physical explanation (and a source) for why an electron would prefer to drop out of 4s and into 3d for Cr and Cu, but not for V or Ni.


 * Understanding the precise meaning of the relative "orbital energies" is a goal and a sticking point for me. Its definition is unclear in various sources. It is an attractive idea to define something like an energy that excludes valence electron interactions (which seem to be dominated by Coulomb interactions), and then explain how the Coulomb interactions among electrons shift the configuration around sometimes. There's a beautiful plot of the orbital energies vs Z you may have seen: it appears a few places on the web like here under Aufbau Prinzip, and in Atkins' book "Quanta" under "Building-up principle". I wish we had it as a commons image. But these sources don't say specifically what "orbital energy" means in an atom's deviously complex many-electron system. It's clearly not referring to the hydrogenic orbital energies (which depend only on n). It seems to be something like the energy to add an electron to a specified orbital starting from the previous element plus a proton, as you suggest. It can't be the full energy for adding the electron, taking into account all interactions among all electrons, or that would always give the right configuration. I would have guessed it's the energy assuming no interaction between valence electrons (electrons added after the last noble gas), but that would result in a sudden jump in energies at the transition from the halogens to the next noble gas, by the definition, and no jump appears in that plot. So, do you know what "orbital energy" means in these descriptions? Or is it only a semi-quantitative description, not to be taken too literally? When you say 7s < 6d, and 6s > 5d, what are the conditions for comparing these, and can you suggest a source that clarifies it? I'm waiting to receive a copy of Atkins' "Physical Chemistry", which seems to be the origin of that plot, and I'm hoping that book will make it clearer. Any of your ideas are welcome. –MadeOfAtoms (talk) 21:07, 15 January 2024 (UTC)
 * When I wrote 7s < 6d for the 6d elements, I meant it in the sense of who gets ionised first in bare ions, e.g. Rf2+ is 6d07s2 (removing electrons from 6d before 7s) whereas Hf2+ is 5d26s0. As for what other authors mean, I'll have to look at the context first before answering. :)
 * P.S. the idea that half-filled or full shells are favoured is intuitively attractive, but a look at the electron configurations of the 4d metals shows that it can't be right; Nb is 4d45s1 apparently for the sake of it. Meanwhile, in the f-rows neither Tm nor Md wants to be f14s1 instead of f13s2. :) I don't really have a simple explanation either for why it happens sometimes and why it doesn't, but probably there is not one anyway. But I defend the idea that it is small enough not to really matter, since Nb and Ta are so similar that they were confused after their discovery, and yet their configuration is different: d4s1 vs d3s2. I'd probably say (more or less following something IIRC Christian Jørgensen wrote) that the exceptions are all metals, so they are going to be positively ionised in chemical reactions. Well, not only do most exceptions disappear once you go to +2 charge, but also it's obvious that the excitation energies are less than the ionisation energy. Maybe it would be a problem for the 5g row (due to extreme interelectronic repulsion I can't exclude that an atom of element 126 as [Og]5g68s2 might spontaneously ionise), but there's so far no proof of that and I expect that thanks to too many subshells being open the PT is going to break down there anyway. Double sharp (talk) 03:16, 16 January 2024 (UTC)

P.S. It's truly difficult to find good examples of metals(0) in compounds to compare electron shell occupancy with bare atoms. This is mostly because most examples of TMs in such low oxidation states are in complexes where pi backbonding offloads a lot of electron density away from the central atom, so much so that the oxidation state is not a good measure of the actual state of the electron shells anymore. Honestly, the best example of a true nonpositively charged TM is just Au(−I) in CsAu. Maybe we'd be better off teaching the (n−1)d < ns energetic order that is true within chemically relevant oxidation states. Double sharp (talk) 04:23, 10 February 2024 (UTC)
 * I'm coming around to seeing your point of view since the order of filling for most +2 and +3 cations is (n−1)d before ns. To the extent that these apply to the +2 and +3 oxidation states that are common in compounds (not the actual charge by any reasonable measure, but seems remarkably relevant anyway) the d fills before s. In real compounds there will be partial occupation of each orbital that depends on how you are projecting the occupied molecular orbitals onto your choice of relevant atomic orbitals, but the main idea is surely still valuable. Some post-f elements seem to be a rare exception: Lu+2 is 4f14 6s1. Lots of exceptions post-5f, but those elements are hard to come by. –MadeOfAtoms (talk) 08:55, 11 February 2024 (UTC)

Lament for superheavies
Not for the first time (thanks to collecting lattice parameters) I wish the heaviest elements were more stable. One could predict some of them would be weird from elementary means: well, first you think about what eka-Hg must be like, and then you realise that the staircase between metals and nonmetals would reach the noble gas group in the 7th period. (Although okay, you'd need spin-orbit coupling to predict eka-Pb being mercury-like.) They would really be interesting elements to study.

But maybe this is asking too much; I already cry for Po, At, Rn, and Fr. :( Double sharp (talk) 17:39, 30 January 2024 (UTC)


 * That would be a trip to see a metallic halogen, runny heavy metals and maybe even a gaseous transition metal Cn. Given the chemical variety of xenon, I suppose radon chemistry is very rich and accessible in actual small experiments, though it's awfully hot to the touch. –MadeOfAtoms (talk) 03:29, 31 January 2024 (UTC)
 * Fun fact: RnF2 is involatile and seems best described as an ionic compound(!). It appears to dissolve as Rn2+ in halogen fluoride solvents. So I expect Rn chemistry will be rich indeed, but also that it will be quite unusual compared to Xe.
 * It's not even certain that Cn will be metallic, because the 7s–7p1/2 gap is large and the covalent radius is probably smaller than Hg. I would bet on it being metallic anyway, but I would not be completely flabbergasted if it was not. Surprised, yes. :) Even if it isn't, it seems likely to me that its alloys (eka-amalgams?) would be; incidentally, the "double amalgam" Hg–Cn system would be cool. On the other hand Og seems like it could be a metal (or at least semiconductor) in the noble gas group. What fun. Double sharp (talk) 04:39, 31 January 2024 (UTC)

Polypropylene article
Hello! I can see you're a regular(ish) editor of the Polypropylene article - it's been vandalised by RedsRedHollow again, but it's so long since I edited an article on here that I can't remember how to do it (also, I see that a manual edit is recommended to avoid alerting this charmer). So perhaps you could do it? JaneVannin (talk) 20:40, 22 May 2024 (UTC)
 * Gladly. I see that RedsRedHollow already has a talk-page warning. Thanks for your past edits and for keeping and eye on the damage. –MadeOfAtoms (talk) 21:42, 22 May 2024 (UTC)
 * Thanks very much! JaneVannin (talk) 21:03, 26 May 2024 (UTC)