Wikipedia talk:WikiProject Elements: Difference between revisions - Wikipedia

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::Thanks. "Post-transition metals" is as popular (or unpopular) as "p block metals". I agree with you(!) that the former term is problematic; that is why I used the term "p-block metals". The fact that "halogens" cuts across metallicity is a reflection of how the term us used. There is not enough yet known, with sufficient confidence, about At and Ts, to prompt them being commonly referred to as any anything else than halogens. I no longer argue for merging alkali and alkaline earth metals nor did I raise that possibility in this thread. There is insufficient support in the literature to support such a change. Equally, you once supported La in group 3; now you support Lu. We are in agreement(!) that the business of WP is to reflect popular usage. Between the survey of 3,300,000 abstracts and however big Google Ngram is, there is no support in the literature to confirm your opinion that there is too much flux to support the proposed categories. Quite the opposite in fact. AM, AEM, Ln, An and TM are shoe-ins, as are metalloids, halogens and noble gases. That there are metals in the p-block is universally recognised, That there are nonmetals between the metalloids and the halogens is universally recognised. [[User:Sandbh|Sandbh]] ([[User talk:Sandbh|talk]]) 06:55, 21 February 2023 (UTC)

:::#So you pick "p-block metals" over "post-transition metals" just to avoid a problem over aluminium, never mind that both are equally unpopular. That already illustrates the problem with making colour categories: the point of all these categories was not to classify all elements on the table once and once only, but to just have names for a roughly similar set of elements that are under the author's scrutiny for the moment. That is why people are fine with "post-transition metals", because Al is not a problem unless you want such a category scheme, and it is why people have no problem with the massive overlap between "transition metals", "rare earth metals", "refractory metals", "noble metals", "coinage metals", and "platinum group metals" and use all these terms (but of course a category scheme with colours cannot deal with this). By turning them into a category scheme with colours, you are going against what sources actually use them for!

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:::#:I pick "p-block metals" over "post-transition metals" since both are equally popular, and the 4-block distinction is maintained. The point of the colour categories is to convey a sense of the left-right transition in metallic to nonmetallic character. As noted, our current PT colour category scheme is non-representative. From my survey of 62 books, just 15% of them had 4-colour, block-based colour schemes. The top three tables, PubChem, RSC, and ptable.com, have multi-colour schemes. Even the American Chemical Society PT, which is conveniently printed on the back of their membership cards, is 10-coloured. Worse, even the Encyclopedia Britannica PT has a multi-colour scheme. Yes, there are minor variations in these five schemes which is why I quoted the ''Nature'' article, and Ngram in order to shed light on the most representative categories. In popular media, PT representations are more often shown with a rainbow colour scheme since people like the colours. Of course, there are uber-categories such as [[rare earth metal]]s, and sub-categories like [[refractory metal]]s, [[noble metal]]s, [[platinum group metal]]s, and [[coinage metal]]s, but their depiction is impractical in our main PT and they are instead discussed in the [[names for sets of chemical elements]] article or individual articles.

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:::#It's literally been known almost since its discovery that astatine does not behave quite like the four more familiar halogens. And why is this argument not allowed for chalcogens, when again it's polonium that's the most ambiguous (well, among natural elements)? Seems to be another arbitrary decision to create a classify-everybody-once scheme, that does not follow from the literature.

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:::#:Astatine is most likely a p-block metal. When it was first synthesized it was suspected of being a metal. This categorisation is not yet popularly reflected in the literature due the rarity of At, the fact of its likely metallicity being obscure, and the overwhelming notion of At being a halogen. The metalloid category cuts across four groups including chalcogens, so use of the chalcogen category is excluded on that basis.

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:::#:What is known about polonium? When the Curies announced in 1898 that they had synthesised polonium they wrote of it as a metal.

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:::#:It has a silvery, metallic appearance; it conducts electricity like a metal; it has the electronic band structure of a metal; its enthalpy of fusion is near the average for close-packed metals; it is soluble in acids, forming the rose-coloured Po⁺⁺ cation and displacing hydrogen; many polonium salts are known; and the oxide (PoO₂), which assumes the fluorite structure more typical of ionic compounds/metallic oxides, is predominately basic in nature.

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:::#:Whether polonium is ductile or brittle is unclear. It is predicted to be ductile based on its calculated elastic constants.[1] It has a simple cubic crystalline structure. Such a structure has few slip systems and "leads to very low ductility and hence low fracture resistance".[2]

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:::#:Polonium also has some intermediate or nonmetallic properties. It has an intermediate coordination number, electronegativity, ionisation energy and metallicity ratio; and it can form anionic polonides; volatile and easily hydrolysed halides (which are soluble in organic solvents); and a volatile and unstable hydride (PoH₂). Most of the latter properties are characteristic of the heavier noble metals or post-transition metals.

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:::#:The elements commonly recognised as metalloids (B, Si, Ge, As, Sb, Te) are semiconductors (B, Si, Ge, Te) or exist in less stable semiconducting forms (As, Sb). Polonium is not known to have a semiconducting form. The commonly recognised metalloids have crystalline packing efficiencies of between 34% and 41%; cf polonium at 52%.

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:::#:If the elements are categorised on the basis of whether they are judged to exhibit a preponderance of metallic or nonmetallic properties (or neither, in which case you may have a metalloid) then I suggest the weight of evidence, in the case of polonium, falls on the metal side of the line. A parallel may be drawn with gold, which exhibits several nonmetallic properties, including auride (Au^–) formation, yet is universally categorised as a metal on account of its distinctive metallic properties.

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:::#:::[1] Legit D, Friák M & Šob M 2010, Phase stability, elasticity, and theoretical strength of polonium from first principles, Physical Review B, vol. 81, pp. 214118–1–19, doi:10.1103/PhysRevB.81.214118

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:::#:::[2] Manson SS & Halford GR 2006, Fatigue and Durability of Structural Materials, ASM International, Materials Park, OH, pp. 378; 410

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:::#When I supported La in group 3 it was based on a mistaken understanding of the chemistry and the state of the literature. So I was using different data from what I know of now, and the old data turned out to be wrong. It happens, there is no shame in changing one's mind for that reason. On the other hand, it appears that you are using exactly the same data (the Ngram results) as you did in 2020, but argue for something different. If the same dataset can support two different schemes it must not have supported either one very clearly.

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:::#:I used the Ngram results from 2020 since I don't expect anything has changed. And the Ngram results are consistent with the colour category proposal. The proposed categorisation scheme is consistent with the ''Nature'' report. Sure, there are a few borderline cases but the broad contours are there. And the fact of the existence of some borderline cases is nicely acknowledged in the [[Periodic_table#Classification_of_elements|periodic table]] article, hence, "A periodic table colour-coded to show some commonly used sets of similar elements. The categories and their boundaries differ somewhat between sources." Well put.

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:::#The surveys would be more convincing if there were not so many hard cases. The boundaries you draw between not losing sleep about them (e.g. Al, Hg, B, and P) and drawing panhandles (Sc and Y) do not seem to have any clear reasoning behind them.

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:::#The question is not whether or not there are metals in the p-block. That is indeed obvious. Neither is it whether or not there are nonmetals between the metalloids and halogens. That is also obvious. The question is: ''which elements are they''? Note in passing that it is not even unheard of for the same author to refer to the same element both as a metal and as a nonmetal, e.g. Sherwin and Weston's 1966 ''Chemistry of the Non-Metallic Elements'' has Sb as a metal on p. 7 and as a nonmetal on p. 115. [[User:Double sharp|Double sharp]] ([[User talk:Double sharp|talk]]) 19:26, 21 February 2023 (UTC)

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:::#:Re 4 and 5. There are only a few hard cases, rather than "many". Even here, that there are hard cases at the boundaries is nothing unusual. Al, and Hg are non-starters given Al is a p-block metal, and Hg is a transition metal. It is 50/50 whether Hg is a transition metal or a post-transition metal. Calling it a transition metal is easier. B is counted as one of the elements most commonly recognised as metalloids. P is indisputably a nonmetal albeit black P, the most stable form, has been referred to as a near metalloid. Sc and Y are where they are (i.e. in the pan handle) due to their two-hatted association with the Ln or rare-earth metals, and the TM.

:::#:Which elements are metals in the p-block is easily resolved. Starting with the six elements most commonly recognised as metalloids, that leaves Al, Ga, In, Tl, Sn, Pb, Bi and Po as metals. On the other side of the metalloids, between the halogens and the noble gases, are C, N, O, P, S, Se nonmetals all. That leaves H, which is nonmetal.[[User:Sandbh|Sandbh]] ([[User talk:Sandbh|talk]]) 00:55, 27 February 2023 (UTC)

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:::#*I have restored the wiki-markup to restore proper numbering and indentation that was eliminated by {{u|Sandbh}}'s large edit. I intend to add mini-signatures to make it clear whose text is who's. [[User:YBG|YBG]] ([[User talk:YBG|talk]]) 04:02, 27 February 2023 (UTC)

:::#:Great post, thanks DS. Sums up this thread, into fine conclusions (I underwrite). No need for me to check out details then. [[User:DePiep|DePiep]] ([[User talk:DePiep|talk]]) 15:56, 25 February 2023 (UTC)