Talk:Nonmetal/Archive 4

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How many types

resolved. YBG (talk) 06:29, 26 January 2024 (UTC)

@Sandbh, we had previously agreed on the wording, but you just now changed “four” to “three to four”. The list following the colon is a list of four items, no more and no less, and so imo the number in the paragraph should be four. One of my previous suggestions had been “four types of elements”, to which you inserted the word “nonmetallic”, but you can remove it if that makes the number four more acceptable. Just please don’t change it back to “3 to 4” without a discussion and agreement to change our previously agreed wording. Thank you! YBG (talk) 06:42, 22 January 2024 (UTC)

@YBG: Thank you. It hadn't occured to me that the adjective "nonmetallic" could in fact accomodate "four types" at the same time as addressing Double sharp's request to refer to three types of nonmetals. I remember the discussion about why I use "nonmetallic". I don't recall having a discussion specificlaly about agreering on either "four" or "three to four" although I know the article has used either expression at varying times.

@Double sharp: Since you expressed a preference for three types of nonmetals, does "four types of nonmetallic elements" works for you?

BTW YBG are there any other remaining concerns you have about the article? Sandbh (talk) 23:19, 22 January 2024 (UTC)

@Double sharp: Does either of these work: four types of nonmetallic elements or else four types of elements? YBG (talk) 04:04, 23 January 2024 (UTC)

@Sandbh: I do not agree with "four types of nonmetallic elements". That outright implies that metalloids are nonmetallic. They are so in some salient chemical properties, but (noting Friend) so are some early transition metals like Mo and W (whose oxides are glass formers, like those of metalloids), and no one would call molybdenum a "nonmetallic element" without a lot of context. And in various other properties, metalloids cluster better with metals. Their thermal conductivity tends to be within the range of metals, and their electronegativity and ionisation energy ranges completely overlap those of metals. And as you already agreed, you could not find a majority of chemists who consider metalloids to be outright nonmetals, so it stands to reason that they should not be emphasised to a greater extent than polonium in metalloid (where you equally well cannot find a majority considering it a metalloid). I would be a lot more comfortable with putting the metalloids as something apart, included for comparison as some of their properties are nonmetallic, but others are not. (Chemically weak metals with a tendency towards amphoterism or worse, like Pb or Mo, may equally well be mentioned briefly.) Double sharp (talk) 08:39, 23 January 2024 (UTC)

@Double sharp. Is a bare four types of elements acceptable? The bullet list itself says metalloids are sometimes instead considered a third category distinct from metals and nonmetals. If that is not strong enough, perhaps we should change “sometimes” to “often”?

Note: the question being addressed in this section is primarily the text of the lead-in to the bullet list. I am trying to avoid the clumsiness of saying “three or four” to introduce a list of four items. YBG (talk) 15:02, 23 January 2024 (UTC)

@Double sharp and YBG: I've boldly changed the topic sentence to refer to three types of nonmetals; and added a sentence between the unclassified nonmetals and metalloid nonmetals that says, "A fourth set of elements are sometimes recognised as nonmetals:". Double sharp, this achieves the "metalloids as something apart" that you said you would be a lot more comfortable with. Does this now work? Sandbh (talk) 05:34, 24 January 2024 (UTC)

Brilliant solution! This allowed me to boldly simplify the lead-in sentence. Unless there is an unexpected objection, I think we can regard this topic as resolved. YBG (talk) 06:52, 24 January 2024 (UTC)

@Sandbh and YBG: I agree: this is an excellent solution that resolves the matter. :) Double sharp (talk) 10:09, 24 January 2024 (UTC)

@YBG and Double sharp: Far out! Thanks for your high praise. I'm suitably chuffed! Good going all! --- Sandbh (talk) 06:02, 25 January 2024 (UTC)

Lead-in to types bullets

resolved YBG (talk) 06:32, 26 January 2024 (UTC)

@YBG: I've changed the mention of number of types to read "three or four types of nonmetallic elements can be most commonly discerned". This is more consistent with the opening paragraph of the section. It also clarifies why "three to four" in that these are the most common approaches. I've used "discerned" rather "seen", as "seen" often refers to the act of visual perception, whereas "discerned" implies a deeper process of understanding, interpreting, or making out something that might not be immediately obvious. I feel this is especially appropriate given the subject matter, including the "are they?/aren't they" nature of the metalloids. --- Sandbh (talk) 00:23, 12 January 2024 (UTC)

@Sandbh What do you think of how it is now? YBG (talk) 18:20, 13 January 2024 (UTC)

I thought this: "In the periodic table, above and to the right of the metals, four types of elements are commonly recognized, from right to left:" was clumsy with its reference to nonmetals being "above" the metals, and the two mentions of "to the right" and "right to left". I've ce'd it to read, "In the periodic table, to the right of the metals, four types of nonmetallic elements can be recognized (proceeding from most to least nonmetallic):" I hope that works. --- Sandbh (talk) 01:00, 14 January 2024 (UTC)

Yea, I think you're right about the clumsiness of my wording. Yours is definitely better.

I am surprised you restored "nonmetallic"; I thought it was the reason for saying "3 or 4" instead of "4". YBG (talk) 01:24, 14 January 2024 (UTC)

Types

resolved. YBG (talk) 06:33, 26 January 2024 (UTC)

@Double sharp: after a very long discussion between @Sandbh and me, I think we’ve come about as far as we can. Would you please read the last paragraph of § Types, the one just before § Noble gases dealing with metal reactivity. Is it acceptable in its current form? If not, what changes do you think are necessary? Is the article better with this paragraph or without it? Thanks! YBG (talk) 03:25, 7 January 2024 (UTC)

Personally, I still do not see the point of having this paragraph in the main text. Nonetheless, it is fairly short, and I would be fine with it as a note. Since it is this short, I would also accept leaving it as it stands, although this is not something I would consider ideal. Double sharp (talk) 04:28, 7 January 2024 (UTC)

@Double sharp and YBG: Thanks. I'll look more closely about moving the paragraph into a footnote. Sandbh (talk) 00:49, 8 January 2024 (UTC)

@Double sharp and YBG: I've moved the paragraph into a footnote, at the end of the four bullet points setting out the four types of nonmetals. Sandbh (talk) 05:33, 8 January 2024 (UTC)

@Sandbh, thank you for accommodating this. I think it works as a footnote, but I wonder about the placement and its relevance as it’s current position makes it look as though it is just related to the metalloids.

Currently the lead-in to the four bullets says:

• ... four types of nonmetallic elements can be discerned:

I’m wondering if it would be better like this:

• ... four types of nonmetallic elements of varying degrees of reactivity^{[n 24]} can be discerned:

@Double sharp, before Sandbh it^or I make any changes, I’d appreciate knowing, Do you agree with my concern about placement of the note?

Also, @Sandbh and @Double sharp, what is your preference order for these seven options (and why?):

1. The separate paragraph as it was before Sandbh converted it to a footnote. -- see special:permalink/1194284385#Types
2. The footnote as Sandbh placed it at the end of the metalloid bullet. -- see special:permalink/1194284904#Types
3. The same footnote placed in the lead-in to the bullets, with the added text 'of varying degrees of reactivity' as I showef above.
4. The same footnote in the lead-in but without the added text.
5. Not including the information, neither as a paragraph nor as a note.
6. Remove the reactivity descriptions from the bullet list of nonmetal types and add this sentence separate from the bullets: The halogen nonmetals are notably reactive, the unclassified nonmetals vary widely in reactivity, the metalloids are generally unreactive,^note and the noble gases are generally inert.^note This could be added to the fuzziness paragraph, either as its first or last sentence, or as a one-sentence paragraph between the bullets and the fuzziness.
7. In a separate paragraph just before § Noble gasses, as special:permalink/1195032848#Types.
8. Some other idea (what?).

I can see advantages and disadvantages to the idea I’ve shown above, so I certainly don’t want to propose it until I’ve heard what others think. Thanks in advance for your input. YBG (talk) 06:33, 8 January 2024 (UTC)

@Sandbh and @Double sharp, I’ve added another option to my list. I’m still interested to know your preference order of these options, and whether you share my concern about the placement of the note. YBG (talk) 14:48, 8 January 2024 (UTC)

@YBG: I feel the way the paragraph reads now works well (#2). I like the reactivity descriptors. They give the reader mental markers. --- Sandbh (talk) 11:33, 9 January 2024 (UTC)

@Sandbh How do you prioritize the other options? YBG (talk) 19:24, 9 January 2024 (UTC)

@YBG: I've changed the footnote back to main body text, and added it the end of the section. I feel that the new intro to the resulting para. i.e., "For context", works very nicely. Of the other options my priority list would be 1 (as modified); and then 2 (as modified). None of the other options work for me: 3. because there's more to the types than reactivity; 4. because talking about metals in the lead-in is out of place; 5. because it's inconsistent (the article mentions other comparisons with metals) and non-encyclopedia; 6. because it removes the mental hooks for the reader. So, I guess what I've now done matches 7. --- Sandbh (talk) 00:39, 12 January 2024 (UTC)

@Sandbh - I was hoping you'd wait for @Double sharp to weigh in before making changes. DS, I'd really appreciate knowing how you'd prioritize the options, including the newly added #7? YBG (talk) 03:45, 12 January 2024 (UTC)

@YBG: Personally, I favour a hybrid of what Sandbh has done and #2. I think the wording is fine and good, but my first preference is still for that paragraph to be a footnote, as it is an addition for context that is not directly related to the article's subject. My second preference is to leave things as they currently stand. Double sharp (talk) 03:53, 12 January 2024 (UTC)

@Double sharp: If it is a footnote, what are your preferences for where to place it? YBG (talk) 03:56, 12 January 2024 (UTC)

@YBG: In the same place it would have been as a paragraph, i.e. as a note attached to the previous paragraph. Double sharp (talk) 03:58, 12 January 2024 (UTC)

@Double sharp. OK, you like the present wording, and you prefer footnote > body text. How do you rank omitting it entirely? (a) footnote > body > omit, (b) footnote > omit > body, or (c) omit > footnote > body? YBG (talk) 16:44, 12 January 2024 (UTC)

@YBG and Double sharp: I like Double sharp's solution. YBG: I'm not sure what the basis for the "omit" option is. The article compares nonmetals and nonmetals at four points in the Physical properties section; the same in the Chemical properties section; and comparisons are again made in the Suggested distinguishing criteria section, and the Comparison of selected properties. An article whose name derives from the "metal" word, would presumably include coverage of the contrasts, overlaps, and similarities. --- Sandbh (talk) 07:02, 13 January 2024 (UTC)

@Sandbh, at one time @Double sharp expressed the opinion that the article would be better without what was then a paragraph. I am inquiring to determine to what extent he still might hold that opinion and how that stacks up against the other two options. As to word derivation, I asked your opinion about this fascinating philosophical issue on my talk page. YBG (talk) 18:03, 13 January 2024 (UTC)

More re types

resolved. YBG (talk) 06:35, 26 January 2024 (UTC)

@Sandbh: I’ve trimmed the descriptions in the list that also serves as a legend. In particular I’ve tried to eliminate the clumsy X-to-Y descriptions. I restored “chemically strong”, it is much crisper than “highly to moderately reactive” and seems supported in the literature. I eliminated “high to low reactivity” which seems to the casual reader (eg FAC evaluators) to be tantamount to meaningless. YBG (talk) 06:07, 31 December 2023 (UTC)

@YBG: I removed the nos. of each type as: after the intro referring to 4 types, there were too many numbers; it isn't necessary to keep track; and the accompanying image does that job. I’ve reinstated mention of the H to M reactive nature of the halogens for 2 main reasons: source-text integrity (regardless how clumsy, not all the halogens are vanilla); and the fact that, as it happens, “chemically strong” is not well-defined in the literature. I reinstated mention of metalloids as "not particularly reactive" as this provides more wriggle room than "relatively unreactive" (As can be a little like Al). This paragraph touches on the heart of the article so I’m particularly invested in it. Sandbh (talk) 11:00, 31 December 2023 (UTC)

@Sandbh: a couple of questions.

1. If having the same absolute level of reactivity isn’t what characterizes the halogens, what does? Can we say they are corrosive? Highly (or relatively) electronegative? Relatively reactive? Very reactive? There must be something they have in common.
2. Can we say that the metalloids are “generally unreactive”?

YBG (talk) 12:02, 31 December 2023 (UTC)

Lifting some descriptions from the subsections, I come up with this:

• relatively inert noble gases
• notably reactive halogen nonmetals —OR— corrosive halogen nonmetals
• less reactive unclassified nonmetals
• generally unreactive metalloids

Thiughts? YBG (talk) 12:19, 31 December 2023 (UTC)

Ok, I’ve implemented these nicely parallel 2-word reactivity descriptions. I’m uncertain whether G17 should be “notably reactive” or “corrosive”; I can live with either. The leftovers are “less reactive” compared to G17, on a period-by-period basis; perhaps that needs a clarifying note but I don’t think so. “Generally unreactive” I think captures the subtleties of the metalloids. YBG (talk) 13:18, 31 December 2023 (UTC)

@YBG: Thanks. *Collectively*, the halogen NM represent the epitome of reactivity. The difficulty is I. It's reactive, sure, but only e.g. a weak oxidising agent, outclassed by O. Among the unclassified NM, O is highly reactive. In c. 2007 the US was losing more than $10 billion each year to corrosion, much due to rusting of iron and steel. The oxidizing agent causing all this is usually O. It further produces molecules of peroxide (O₂^2–) and superoxide (O₂^–), after it reacts during respiration to produce water. These highly reactive forms of O would damage the delicate biological structures within a cell. Consequently, most organisms that breathe air have evolved enzymes to deal with these dangers. "Generally unreactive" works OK for the metalloids. "Notably reactive" works OK for the halogen NM. However, for the UN one would have to say, "notably to less reactive" i.e. that overlap thing is evident again. --- Sandbh (talk) 06:54, 1 January 2024 (UTC)

What about “variably reactive”? YBG (talk) 05:17, 2 January 2024 (UTC)

@Sandbh?? YBG (talk) 05:18, 2 January 2024 (UTC)

@YBG: Thank you. “Variably" reactive sounds like each of the UN are individually variably reactive, which is not so. How about "mixed reactivity”? Then we would have:

• relatively inert noble gases
• notably reactive halogen nonmetals
• mixed reactivity unclassified nonmetals
• generally unreactive metalloids

I like it so much I’ll go ahead and do the edit.

— Sandbh (talk) 10:03, 3 January 2024 (UTC)

Great. I think we’ve resolved all the major issues in this section. YBG (talk) 03:31, 7 January 2024 (UTC)

Outstanding items from FAC7 nomination

resolved. YBG (talk) 06:37, 26 January 2024 (UTC)

@Graham Beards, YBG, and Double sharp: Please see below. @Michael D. Turnbull, Mirokado, and Jo-Jo Eumerus: fyi.

I understand that the following items had still to be checked off:

A small mention of metalloid outliers (Double sharp)

"If you like, there may be room for an "Outliers" sub-sub-section at the end of the Metalloids section. This could address Po, Al, C, Bi, Be, Sn, Ga and Pb, all of which have been identified as metalloids in at least one source, per the Lists of metalloids article".

@Double sharp: Done. I've added such a (condensed) section. --- Sandbh (talk) 06:35, 24 October 2023 (UTC)

@Sandbh: Thanks, I like it. I feel it nicely illustrates the continuum between metals and nonmetals. Double sharp (talk) 08:56, 24 October 2023 (UTC)

Complementary pairs (YBG)

Please see the new section about this, hereunder.

More tendency speak (Double sharp)

"@Double sharp: I suspect there is agreement between the sources in the sense that they all draw on (prioritise?) a few or several properties from the same big set of all properties associated with nonmetals. There are of course differences in just which few or several properties each author chooses. Does the question then become which few properties can do a reasonable job of more or less encompassing the big set? --- Sandbh (talk) 04:05, 22 October 2023 (UTC)[reply]

@Sandbh: I don't think we should be the ones making that decision. I think we should rather give the list, which is mostly agreed on (modulo what exactly people make of metalloids), and then mention tendencies that people have used as criteria. Double sharp (talk) 04:07, 22 October 2023 (UTC)[reply]

@Double sharp: OK; if you feel there's a need for more tendency-speak in the article, that should be doable. --- Sandbh (talk) 04:26, 22 October 2023 (UTC)"

An extraction periodic table (YBG)

"This would be a fun place to insert another PT extract, with five colors (for the five sources) and two shadings (solid for exclusively, striped for mainly)"

@YBG: Done: Thanks; I've now added such an extract. --- Sandbh (talk) 04:03, 27 October 2023 (UTC)

Double up (Graeme Beards)

"It some instances it's getting worse. See this in the Lead for example: "There is no universally agreed definition of the term... there is no universally accepted definition of a nonmetal". How many times do the readers need to be told?"

Done. This has been fixed. Sandbh (talk) 07:11, 23 October 2023 (UTC)

--- Sandbh (talk) 23:37, 22 October 2023 (UTC)

@Double sharp, @Graham Beards: I believe everything in this section has been resolved, but I hesitate to collapse it as it contains issues you folks raised, not me. I do expect we would benefit from another read through to reduce or eliminate tendency speak, but that, imho is a project for another day and another section. YBG (talk) 05:50, 29 November 2023 (UTC)

@Double sharp/Sandbh/Graham Beards There’s been nothing new said in over a month; I’ll wait another week and mark this section resolved. YBG (talk) 03:41, 7 January 2024 (UTC)

regarding "Types, metalloids"

Resolved --- Sandbh (talk) 05:07, 3 February 2024 (UTC)

AFAIK, semiconducting Sb is only stable as a very thin film (doi:10.1039/D3NR03536K). If we're going to include this sort of thing, then we'd presumably have to also note that B can metallise under such conditions (see borophene). Graphene also counts, though C is placed under unclassified nonmetals. Double sharp (talk) 13:54, 9 January 2024 (UTC)

@Double sharp: Thanks; I've added "Single-layer materials" to the Allotropes hatnote. The metallisation of some of these materials is accommodated in the way the topic sentence in the nonmetal article is composed i.e., "each with distinct physical properties that may vary between metallic and nonmetallic." --- Sandbh (talk) 00:00, 12 January 2024 (UTC)

I agree with this addition, but I do think that the difference should be put in context in "Types, metalloids". The single-layer situation is quite different from the bulk situation: B and C can metallise, whereas Sn, Sb, and Bi either demetallise (fully or partially, considering topological insulators as partial demetallisation) or are theoretically expected to do so. To my mind, this is a rather similar situation to changes under pressure, in which for example Na can demetallise (and then remetallise at extremely high pressures) and Xe can metallise. I think that if you're going to put semiconducting Sb in the main text, then some kind of context is needed to make it clear that unlike semiconducting As, this is not a form that exists in quite usual conditions. At least, if something was only true of graphene and not graphite, I'd feel the need to spell it out specifically, as probably the 2D structure is then related to why it only works in that case.

The way I'd deal with this myself would be to add to the "Allotropes" section a sentence reading "Additional allotropes may occur in more exotic conditions, such as in single-layer materials or under high pressure. The allotropes formed may have unexpected properties: for example, sodium transforms from a metal to a glass-like insulator at ~200 GPa (ref), and oxygen becomes a metallic conductor at 96 GPa (ref). Bulk boron is a semiconductor, but boron nanotubes have metallic properties (ref); contrariwise, single-layer bismuth is a topological insulator, with electrons only free to move along the surface and not the interior (ref). As these properties are quite distinct from bulk behaviour at standard conditions, the remainder of the article will not consider them." And then simply fix the sentence under "Types, metalloids" so that it only lists As and not Sb as having a stable semiconducting form (which is correct under this reasonable assumption). Double sharp (talk) 03:56, 12 January 2024 (UTC)

P.S. regarding high-pressure electrides: more are expected to do it, but only for Li and Na has it actually been seen so far. Double sharp (talk) 09:29, 12 January 2024 (UTC)

@Double sharp: Thank you. The context in "Types, metalloids" is given by the following two sentences: "They [metalloids] are brittle and poor-to-good conductors of heat and electricity. Specifically, boron, silicon, germanium, and tellurium are semiconductors." In this context, it follows that, "Arsenic and antimony have the electronic structures of semimetals, although both have less stable semiconducting forms.^[9]" The semiconducting properties of the metalloids are mentioned due to the strong association of the two concepts. The single layer situation is not relevant here although it is in the Allotropes section. I've nevertheless added a footnote about Sb forming a semiconducting allotrope only in thin film form.

I've adjusted the allotropes section to refer to "less stable" allotropic forms. There is no need for further detail given the hatnote says, "For a more comprehensive list, see Allotropy § Non-metals, and Single-layer materials." --- Sandbh (talk) 06:44, 22 January 2024 (UTC)

@Sandbh: By the logic that the "single layer situation is not relevant here", it seems to me that single-layer allotropes ought not to be included in the "Metalloids" section at all. It is exactly the same kind of thing as including metallic Xe at high pressure under the "noble gas" section: cool, but not really having anything to do with the usual classification. Similarly, it seems to me that allotropes of halogens are also misleading inclusions in the "Allotropes" section without a mention that they are exotic high-pressure phenomena, not something like O₃. To my mind, some kind of context is needed to make it clear what happens at normal conditions and what does not – especially when it gets at the heart at what a nonmetal is. Will anyone call Na a nonmetal? No, but it starts insulating at high pressure. So it seems that a statement about standard conditions is absolutely needed.

P.S. Sn also has an amorphous semiconducting form at low temperature.

P.P.S. The facts that (1) "metalloid" and "semiconductor" are strongly associated concepts and (2) Sb has no bulk semiconducting allotrope suggests something about Sb, especially when that puts it in the same boat as Bi. ;) I wonder if confusion about its allotropes had something to do with antimony's inclusion, perhaps regarding the stability of the black allotrope in bulk, or the existence of the yellow "allotrope" (thought to be Sb₄, but probably is not a real allotrope). Double sharp (talk) 08:33, 23 January 2024 (UTC)

@Double sharp: The logic that the "single layer situation is not relevant here" is that the whole article is about the applicable nonmetals in their most stable states, in ambient conditions, unless mentioned otherwise. Pls see the hatnote to the Definition and applicable elements section. The only halogen allotrope mentioned is that of (amorphous) iodine.

I mention the less stable semiconducting alltropic forms of As and Sb in the Metalloids section since B, Si, Ge and Te are semiconductors. The footnote clarifies that the semiconducting allotrope of antimony is known only in thin-film form. Undoubtedly, the existence of black antimony and the purported existence of other allotropes of Sb contributed to perceptions of its status.

PS: Here's a 1905 take on Sb:

"The elements are ordinarily classified as metals and non-metals, but this classification is by no means perfect, for there is no sharp line of demarcation between the two groups, the properties gradually varying from the extremely electropositive to the extremely electronegative. Another reason for confusion lies in the fact that there is no strict definition for a metal. The classification depends on both chemical and physical properties, and consequently a chemist would ordinarily classify an element like antimony, nearly all of whose chemical properties are non-metallic, as a non-metal; while a physicist would probably classify it as a metal, for its physical properties are nearly all metallic. Physically, metals ordinarily have a peculiar luster known as metallic luster, which may be seen in the case of polished silver or steel, or freshly cut lead; and are comparatively good conductors of heat and electricity. The non-metals do not possess these properties, or if they possess them at all, it is in a less degree."

• ICS Reference Library 1905, Inorganic Chemistry, International Textbook Company, Scranton, sect. 8, p. 45

Sandbh (talk) 07:19, 26 January 2024 (UTC)

So that makes Sb quite like U, which Friend also thinks is not very metallic in chemistry. :)

The point is: if you're going to mention nonmetallic Sb in a thin-film, then by the same logic other weird thin-film cases also become relevant, such as B and C that can both metallise, and Bi which demetallises. I'd feel happier with this if it was stated up front in the main text that semiconducting Sb is only a thin-film phenomenon, rather than relegating this caveat to a footnote. Double sharp (talk) 08:08, 27 January 2024 (UTC)

I've converted the footnote about amorphous Sb into main body text. See para. 2, Metalloids. --- Sandbh (talk) 02:19, 1 February 2024 (UTC)

Thank you. That looks OK to me. Double sharp (talk) 16:50, 2 February 2024 (UTC)

Opening PT excerpt

Resolved YBG (talk) 04:11, 17 February 2024 (UTC)

We hashed this out before, but I’m wondering about At again. Could it be like Cn/Fl/Og with a “status unclear” legend, relegating any other info to a note? It would make the opening graphic a lot cleaner. YBG (talk) 05:49, 5 February 2024 (UTC)

I agree. The same situation applies to all four: no one has ever made enough to see them in bulk, so nobody knows if they are physically metals or not, and there are reasons and sources who guess both ways. Double sharp (talk) 14:56, 5 February 2024 (UTC)

@Double sharp: Do you think a note is needed beyond status unclear? YBG (talk) 15:02, 5 February 2024 (UTC)

@YBG: Why not make the legend "status unclear, too radioactive to be seen in bulk?" That's short enough for a legend and explains the situation completely. (It wouldn't include Fr: that's indeed too radioactive to be seen in bulk, but its status is clear.) Double sharp (talk) 15:05, 5 February 2024 (UTC)

@YBG and Double sharp: I've boldly updated the image to show At with a blank background, and simplified the accompanying extract. Nice idea YBG. --- Sandbh (talk) 01:21, 6 February 2024 (UTC)

Thanks YBG (talk) 04:10, 17 February 2024 (UTC)

Johnson’s NM characteristics

resolved YBG (talk) 04:57, 17 February 2024 (UTC)

Can we eliminate the table in favor of expanding the numbered list with sub points?

1. Under (1) comes three lists (a) gases (b) other insulators (c) semiconductors
2. Under (2) comes (a) hard and brittle and (b) soft and crumbly conductors

But then I got stuck not knowing what to put under (3)

If the table remains, it needs to be better coordinated with the numbered list.

But I prefer removing the table On wide screens, it pushes the EN/density chart down too far  :YBG (talk) 05:33, 25 January 2024 (UTC)

@YBG: I'm looking closely at the numbered list and its coordination with the numbered list. This will take me a little while. Sandbh (talk) 11:57, 25 January 2024 (UTC)

@YBG: I've deleted Johnson's table and adjusted the main body text. Having more closey read Johnson I didn't appreciate quite how much insight he showed. --- Sandbh (talk) 04:28, 26 January 2024 (UTC)

Thanks. Looks nice. One question: the way it is worded, it isn’t clear what determines metal-ness: is it primarily the physical character (gaseousness, pliability)? Or is it conductivity and acidity if oxides? Or, put another way:

• Are B, Si and Ge nonmetals because they are hard and brittle? Or because they are semiconductors?
• Are C, P, S, As, Sb, Te and I nonmetals because they are soft and crumbly? Or because their oxides are acidic?

At issue here is, what is Johnson saying? Perhaps he is saying one property is determinative and the other is confirmative. One also wonders whether Johnson says a similar thing about the gases and their non-conductivity.

YBG (talk) 05:45, 26 January 2024 (UTC)

@YBG: Johnson's book is an intro to the descriptive chemistry of the nonmetals so he didn't provide a definition of a metal. What he did was provide a PT showing the location of metals, semimetals, and nonmetals. He then said the most obvious properties to classify an element were its physical state; appearance; and malleability and ductility. He added that for elements in the vicinity of the semimetals other properties must be considered: conductivity; crystalline structure; IE, EA and EN; and the acidity of oxides and hydroxides. What I added to the article is concerned only with what he wrote about nonmetallic elements.

• B, Si and Ge are not metals as they are hard and brittle, and semiconductors.
• C, P, S, As, Sb, Te and I are nonmetallic as they are soft and crumbly, and since their oxides are acidic this is "indicative" (the term used by Johnson) of nonmetallic character.

--- Sandbh (talk) 04:20, 27 January 2024 (UTC)

That's an interestingly circular way of looking at it, with IE, EN, and acidity only mattering once the semimetals are nearby. Except that the supposedly defining criteria (physical state, appearance, and malleability/ductility) could never define semimetals by themselves, noting just how many brittle metals there are, and how metalloids tend to resemble metals in appearance. We are left with another definition that at face value agrees with Friend's point: W is brittle, has an acidic oxide, and has a very high EN, and by this kind of logic has a more nonmetallic chemistry than Te (lower in EN and in oxide acidity).

In any case, I rather think this, Friend, and the EN table suggests that some mention ought to be made of the chemically weak very electronegative metals in the d and p blocks, that are well-known to have very nonmetal-like behaviour, e.g. Sn, W, Hg, Bi. They seem about equally relevant as metalloids, which are also not generally considered nonmetals proper, though they are recognised to have nonmetal-like properties. Double sharp (talk) 08:02, 27 January 2024 (UTC)

@Double sharp: Yes, I thought what Johnson wrote was interesting enough to be worthy of a summary paragraph.

I've added some words about e.g. W and Au as examples of metals with nonmetal-like behaviour, to the end of the Property overlaps subsection. They provide a nice complement to nonmetals showing metal-like behaviour. --- Sandbh (talk) 07:27, 28 January 2024 (UTC)

Apparently tungsten oxides are soluable in concentrated hydrofluoric acid. The dissolution reaction presumably involves protonation of the oxide with formation of soluble tungsten fluoride complexes. I'll remove reference to the oxides and maybe say something about W's anionic aqueous chemistry. --- Sandbh (talk) 21:46, 28 January 2024 (UTC)

It seems much more likely to me that WO₃ simply gets partially fluorinated by reaction with HF, like how UO₃ reacts with HF to form UO₂F₂.

It's fairly obvious that W oxides are predominantly acidic in their properties. Here's a source even explicitly calling it one of the most acidic transition metal oxides. Even if the reaction with HF is really an acid-base reaction (which seems unlikely), don't call N₂O₅ amphoteric just because nitronium salts exist. Double sharp (talk) 09:42, 30 January 2024 (UTC)

This site suggests WO₃ + 4HF → H₂[WO₂F₄] + H₂O. That seems plausible given the existence of Na₂[WO₂F₄]. It seems to be both a fluorination reaction and an acid-base reaction given the formation of H₂O, which I understand is a typical feature of acid-base reactions. Sandbh (talk) 12:21, 31 January 2024 (UTC)

H/C/N/O/Si percentages in earth’s domains

resolved YBG (talk) 17:10, 19 February 2024 (UTC)

The 2nd sentence of the 3rd paragraph reads:

Five nonmetallic elements—hydrogen, carbon, nitrogen, oxygen, and silicon—make up the overwhelming majority of the Earth's crust, atmosphere, oceans and biosphere.[n 2]

The note, based on the table in § Abundance of nonmetallic elements, says:

By weight, O/Si/H comprise 83.9% of the crust; N/O, 99% of the atmosphere; O/H, 99.4% of the hydrosphere; and O/C/H/N, 96% of the biomass.

Wouldn’t it be nicer to say:

By weight, hydrogen, carbon, nitrogen, oxygen, and silicon comprise xx.x% of the crust, xx.x% of the atmosphere, xx.x% of the hydrosphere, and xx.x% of the biomass.

To do this, someone ( Sandbh?) needs to look up this data in the refs:

• C/N are what % of the crust?
• H/C/Si are what % of the atmosphere?
• C/N/Si are what % of the oceans?
• Si is what % of earth’s biomass?

Is it worth doing the research? Or is it just fine the way it is? YBG (talk) 04:34, 7 February 2024 (UTC)

The quantities of C/N in the crust (0.02% to 0.03%; 0.003% or less); H/C/Si in the atmosphere; C/N/Se in the oceans; and Si in the biomass, are negligible. --- Sandbh (talk) 07:18, 9 February 2024 (UTC)

Thanks, @Sandbh. I nave simply use “over xx%” so the note now reads

By weight, hydrogen, carbon, nitrogen, oxygen, and silicon make up over 83.9% of the crust, over 96% of the biomass, and over 99% of the oceans and atmosphere.

YBG (talk) 04:08, 17 February 2024 (UTC)

On second thought, I moved the info from a note in the lead section to the body of the article.

The 2nd sentence of the 3rd paragraph of § top now reads:

Five nonmetallic elements—hydrogen, carbon, nitrogen, oxygen, and silicon—make up the overwhelming majority of Earth's oceans, atmosphere, biosphere, and crust.

The 2nd paragraph of § Abundance of nonmetallic elements now reads:

Five nonmetals—hydrogen, carbon, nitrogen, oxygen, and silicon—form the vast majority of the directly observable structure of the earth: about 84% of the crust, 96% of the biomass, and over 99% of the atmosphere and hydrosphere, as shown in the accompanying table.^[ref]

Thoughts? YBG (talk) 21:11, 17 February 2024 (UTC)

Looks good. --- Sandbh (talk) 04:03, 18 February 2024 (UTC)

Oxides

resolved Sandbh (talk) 00:02, 24 February 2024 (UTC)

it is clear from the note that while metal oxides are mostly basic, some are acidic or amphoteric.

But what about nonmetal (or metalloid) oxides? Are any basic? Are any amphoteric? Or are they ALL acidic? YBG (talk) 21:37, 3 February 2024 (UTC)

This is noted at least in the lede: "While oxides of metals tend to be basic, those of nonmetals tend to be acidic"; and in the chemical properties section: "Nonmetals have relatively high values of electronegativity, and their oxides are therefore usually acidic." The Comparison of selected properties table notes that metalloid oxides are amphoteric or weakly acidic. --- Sandbh (talk) 12:14, 4 February 2024 (UTC)

H₂O is clearly amphoteric. GeO, Sb₂O₃, and I₂O are probably best considered amphoteric as well, even under a more restricted definition that would call As₂O₃ acidic, since for example hypoiodous acid is so weak and can reasonably end up protonated in aqueous solution.

In fact, there is a pattern to metal oxide acidity: they tend to become more acidic as the metal gets more electronegative and its oxidation state rises. So, for example CrO is basic, Cr₂O₃ is amphoteric, and CrO₃ is acidic. In oxidation state +2, amphotericity is pretty unusual and only seen for quite weak metals (BeO, ZnO, SnO, PbO); in oxidation state +4, you have to go to the largest and most electropositive +4 cations of all (early actinoids) to get basic oxides, e.g. ThO₂ and UO₂. +3 is more of a mixed bag, and states +5 and above essentially cannot be basic (unless you want to give a sympathetic pass to Pa₂O₅, perhaps). Some heavy transition metals don't have any clearly basic oxides at all for this reason, e.g. Ir with only IrO₂. This is the same as the pattern noted in the article for nonmetals, only stated the other way: H is the prime example of a nonmetal with only an amphoteric oxide because the only available charge (+1) is just too small and the nonmetal just isn't that electronegative (whereas Cl₂O is clearly acidic). So perhaps the extended version of the pattern merits a footnote. Double sharp (talk) 14:38, 5 February 2024 (UTC)

OK, I changed the end of the 1st paragraph of § Definition and applicable elements to read When combined with oxygen, nonmetals never form basic oxides, but metals usually do. I trust that is acceptable to everyone. YBG (talk) 16:48, 5 February 2024 (UTC)

@YBG and Double sharp: Ce'd to now read:

"When combined with oxygen, nonmetals do not form basic oxides (while metals usually do).[4]"

PS. Hydrogen peroxide is weakly acidic.

--- Sandbh (talk) 01:28, 6 February 2024 (UTC)

This wording is fine with me.

Peroxides and superoxides are different cases; then you're changing the anion. Double sharp (talk) 04:48, 6 February 2024 (UTC)

Thank you. The oxide article opens with, "An oxide (/ˈɒksaɪd/) is a chemical compound containing at least one oxygen atom and one other element[1]. On that basis, a peroxide is an oxide.

Tangentially, I recall Mendeleev initially locating H over Cu-Ag-Au supposedly on the basis that all four form peroxides. In the event, H does; Cu does; Ag forms silver(II) oxide (AgO), or silver peroxide, which is actually a mixed oxidation state silver(I,III) oxide; Pourbaix said of gold peroxide AuO₂:

3.4.2. Gold peroxide Au0₂

Gold peroxide appears on gold which is anodically polarized in acid and alkaline solutions. From Fig. 1 it seems to be a particularly unstable substance with a great tendency to decompose into Au₂0₃ and 0₂; it is a powerful oxidizing agent, oxidizing chlorides to chlorine, for example. It dissolves in very acid and very alkaline solutions, being reduced to the trivalent state and evolving oxygen.

Mendeleev clearly considered peroxides a different case from normal oxides in his Faraday lecture. Double sharp (talk) 14:20, 16 February 2024 (UTC)

@Double sharp: Thanks; good to know. --- Sandbh (talk) 12:42, 17 February 2024 (UTC)

I’ve tweaked the wording at § Chemical properties of nonmetals. — Preceding unsigned comment added by YBG (talk • contribs) 04:52, 17 February 2024 (UTC)

Are there any unresolved issues left in this section? YBG (talk) 19:01, 19 February 2024 (UTC)

@Double sharp? @Sandbh?

——— YBG (talk) 19:02, 19 February 2024 (UTC)

@YBG: I'm a bit busy at the moment. Please give me a couple of days to respond to the pings. :) Double sharp (talk) 02:16, 20 February 2024 (UTC)

I don't believe so. --- Sandbh (talk) 05:15, 20 February 2024 (UTC)

Just had time to look at it. I agree with Sandbh; no further issues. Double sharp (talk) 10:53, 23 February 2024 (UTC)

Scope

resolved Sandbh (talk) 00:03, 24 February 2024 (UTC)

List article ledes often include a clear statement of the scope of the list, that is, the inclusion criteria. This is not a list article, but it seems it might benefit from a clear scope statement early in the article. This should at minimum include the exclusion of astatine because its bulk properties are not well attested and inclusion of the metalloids for comparative purposes. Another possible addition would be explaining the use of “nonmetal” vs “nonmetallic element” if we decide to use these terms consistently. I’ve thought a bit about where to put this, and it seems there are three good choices: (1) as the last sentence of the first paragraph (2) as a new paragraph inserted between the first and second (3) as a new paragraph at the end of the top section. There are certainly other choices too. I don’t feel strongly about the location except that the earlier the better and that it should be in the top section. As it currently stands, the scope dt at statement comes much later. Thoughts anyone? YBG (talk) 06:56, 22 January 2024 (UTC)

This could largely be accommodated by showing the start of the article as follows (bold = new):

This article is about a class of up to two dozen or so nonmetallic chemical elements. For the use of the term nonmetal in astronomy, see nonmetal (astrophysics). For nonmetallic substances, see materials science.

A nonmetal is a chemical element that mostly lacks metallic properties. Seventeen elements are generally considered nonmetals, though some authors recognize more or fewer depending on the properties considered most representative of metallic or nonmetallic character. Elements on the borderline, which are sometimes instead referred to as metalloids, further complicate the situation. They are included for comparative purposes, given their predominately nonmetallic^[footnote] chemistry.

Footnote: The term "nonmetallic" generally encompasses nonmetals and metalloids; "nonmetal" generally excludes metalloids. Sandbh (talk) 00:12, 23 January 2024 (UTC)

@YBG: --- Sandbh (talk) 00:13, 23 January 2024 (UTC)

Suggestions

• Hat note: Can we avoid saying both up to and or so? Maybe just up to NNN or else about MMM to NNN?
• Last sentence para 1: Complicating the situation, the borderline metalloids are sometimes considered a category separate from metals and nonmetals.
• New para 1.5: This article includes metalloids for comparative purposes, given their predominately nonmetallic chemistry. The term "nonmetallic" is used to include both nonmetals and metalloids; "nonmetal" excludes metalloids. Astatine is only mentioned briefly due to uncertainty over its bulk properties.

Thoughts? YBG (talk) 04:00, 23 January 2024 (UTC)

Another idea: using "nonmetal" to exclude the metalloids, and using "non-metallic" with a hyphen to include them. YBG (talk) 04:34, 24 January 2024 (UTC)

@YBG: Hat note. We have to say "up to" since we are talking about a range of around 17 to 23 elements. The "two dozen or so" is way of saying 23 is about two dozen. --- Sandbh (talk) 06:06, 26 January 2024 (UTC)

I don’t mind the current hat note “two dozen or so”; I’m also ok with “up to two dozen”or even “17 to 23” (if those are the right numbers). All I was objecting to was saying both “up to” and also “or so” as your proposal just above suggests. YBG (talk) 06:21, 26 January 2024 (UTC)

Last sentence para 1: I've changed this to read: "Complicating the situation are elements for which it becomes harder to decide whether metallic or nonmetallic properties are more pronounced." --- Sandbh (talk) 06:06, 26 January 2024 (UTC)

New para 1.5: I've incorporated this into the "Definition and applicable elements section". I've included "generally" provisos. The suggestion. "The term 'nonmetallic is used to include both nonmetals and metalloids; 'nonmetal' excludes metalloids" is too precise for chemistry, which has all sorts of fuzzy definitions. Astatine has already been mentioned in the caption to the lede image. --- Sandbh (talk) 06:06, 26 January 2024 (UTC)

Yes, it is too precise for chemistry, I am only suggesting that we make a conscious editorial decision for this article to decide whether each statement is meant to include the metalloids or not and consistently use terms within this article. YBG (talk) 06:25, 26 January 2024 (UTC)

@YBG: I've trimmed the footnote about the terms metallic and nonmetallic. Since the hatnote at the top of the article refers to around two dozen nonmetals, metalloids are included in the scope of the article, either for comparitive purposes or when they are sometimes counted as nonmetals rather than metalloids or when the metalloids are counted as a kind of nonmetal. Usage of the terms metal, nonmetal, metallic or nonmetallic is then a question of which sounds or reads better in the passage in question. --- Sandbh (talk) 12:21, 30 January 2024 (UTC)

The purpose of a wp:hatnote is to help readers locate a different article if the one they are at is not the one they're looking for, not to define the scope of the article itself. YBG (talk) 13:52, 3 February 2024 (UTC)

I have simplified the 1st paragraph so it now ends with a simple statement of scope. YBG (talk) 19:15, 3 February 2024 (UTC)

@YBG: I've further streamlined the 1st paragraph. Self-evidently, there cannot be an "exact" number of nonmetals. I submit that it is not a good idea to refer to metalloids at this point given the article is about nonmetals, and metalloids have not even been defined yet.

Here's how it reads now plus the two preceding versions:

Current: A nonmetal is a chemical element that mostly lacks distinctive metallic properties. There are up to about two dozen nonmetals, with the count varying due to some borderline cases.

Preceding: A nonmetal is a chemical element that mostly lacks metallic properties. The exact number depends on the defining properties used and on whether metalloids are included. This article covers 23 elements: the 17 generally considered nonmetals and the 6 most commonly recognized as metalloids.

Antepreceding: A nonmetal is a chemical element that mostly lacks metallic properties. Seventeen elements are generally considered nonmetals, though some authors recognize more or fewer depending on the properties considered most representative of metallic or nonmetallic character. Complicating the situation are elements for which it becomes harder to decide whether metallic or nonmetallic properties are more pronounced.

--- Sandbh (talk) 00:43, 5 February 2024 (UTC)

Assuming that you objected the scope statement due to its length, I shortened it in hopes it meets with your approval:

A nonmetal is a chemical element that mostly lacks distinctive metallic properties. Although definitions vary, this article covers 23 elements, including the most commonly recognized metalloids.

I think an explicit scope statement early on is very important, but it should be coupled with an acknowledgment that it is not universally accepted. YBG (talk) 02:40, 5 February 2024 (UTC)

@YBG: I wasn't so fussed about paragraph length. The shortened version defines the subject matter in the 1st sentence, which is as it should be. There are some difficulties with the 2nd sentence:

1. In mentioning that "definitions vary", it contradicts the 1st sentence.
2. Bearing in mind the general reader, it's not a good idea to introduce a new term into the opening paragraph, i.e. "metalloids".
3. The elements most commonly recognized as metalloids are not always recognised as such. B and Si may instead be counted as nonmetals; any of Ge, As, and Sb as either metals or nonmetals; and Te as a nonmetal. It becomes too hard to capture such nuances in the scope statement.
4. "23" implies a level of precision not found in the literature.

For these reasons I've changed the scope statement back to the version that says:

A nonmetal is a chemical element that mostly lacks distinctive metallic properties. There are up to about two dozen nonmetals, with the count varying due to some borderline cases.

I feel that mentioning "borderline" cases nicely gels with the notions of "up to about", and the varying count. --- Sandbh (talk) 00:55, 6 February 2024 (UTC)

@Sandbh Replying to your points:

1. In “definitions vary” I summarize previous versions of this paragraph AND § Definition and applicable elements. Perhaps if modified by “precise” it would be acceptable?
2. Yes, the general reader may not understand ‘metalloid’, but the specialist should be told up front whether they are included. Maybe “borderline metalloids”?
3. I will keep this in mind.
4. “23” is intended to imply precision, not of the literature, but of this article. This article covers exactly 23 elements, no more and no less

YBG (talk) 05:30, 6 February 2024 (UTC)

I can’t think of any way to improve on the two scoping sentences that now appear in the first paragraph:

Seventeen elements are widely recognized as nonmetals. This article also covers six borderline elements ("metalloids"), some or all of which are sometimes considered nonmetals.

———YBG (talk) 05:35, 17 February 2024 (UTC)

@Sandbh, I think issues in this section are resolved now. Thoughts? YBG (talk) 19:05, 19 February 2024 (UTC)

I believe so. --- Sandbh (talk) 05:16, 20 February 2024 (UTC)

A thought on the history

resolved YBG (talk) 22:13, 5 March 2024 (UTC)

It occurs to me that there must be a missing link between Dupasquier and Dumas on the one hand, and the modern idea on the other, because they consider B and Si to be nonmetals but are not agreed on the more metalloidal elements. Dumas includes As but not Se, and Dupasquier includes Se but not As; neither include Ge, Sb, or Te. The 1911 Britannica article on chemistry thinks that B, Si, Se, and Te are nonmetals, but not Ge, As, and Sb. I assume this changed when people started using "metalloid" for an intermediate set instead, but in that case the inclusion of such elements as primarily nonmetals gets somewhat iffy, since mostly people talk about them as intermediate between metals and nonmetals. Back when there were only two categories and no intermediate ones, it does not seem as though Ge, As, and Sb were considered nonmetals that often. Double sharp (talk) 04:27, 7 January 2024 (UTC)

@Double sharp: Thanks. I've added a paragraph about the metalloids.

Early on the article says, "Nonmetallic chemical elements generally have low density and high electronegativity" and "The six most commonly recognized metalloids have relatively low densities and predominantly nonmetallic chemistry and are typically seen as intermediate between metals and nonmetals;[10] they are included in this article for comparison: B, Si, Ge, As, Sb, Te." The comparison of properties section adds, "The dashed lines around the columns for metalloids signify that the treatment of these elements as a distinct type can vary depending on the author, or classification scheme in use." --- Sandbh (talk) 05:16, 8 January 2024 (UTC)

@Sandbh: Regarding the paragraph: what elements do Newth and Friend consider to be metalloids?

P.S. The discoverers of tellurium certainly thought it was a metal. So did Berzelius, per what Weeks quotes of him in doi:10.1021/ed009p474. So they presumably cannot have thought that it had a "predominantly nonmetallic chemistry": that view must have come later. Speaking a lot earlier, Agricola considered Sb to be as metallic as Pb in De natura fossilium (quoted in Metal#The Renaissance), which makes sense when one considers that Pliny confused the two. J. R. Glauber likewise thought Sb was a metal on a par with Co, Zn, and Bi: Weeks' Discovery of the Elements (p. 144) quotes him as writing And if we nevertheless maintain that each planet gives birth to its own metal, to which star should one assign bismuth, cobalt, antimony, and zinc? On the other hand, on p. 261 of the same book we find a quote of Scheele calling Mo a "half-metal". Double sharp (talk) 06:02, 8 January 2024 (UTC)

@Double sharp: Newth says the following elements encompass metalloid and nonmetals: As, B, Br, C, Cl, F, H, I, N, O, P, Se, Si, S, Te.

Friend says:

"The difficulty of drawing a dividing line between metals and non-metals is clearly shown by the existence of an alternative method of classifying the elements, which divides them into three groups, namely, non-metals, metalloids, and metals. A metalloid is an element which, although it resembles a metal in most characteristics, yet lacks some one or more of the features which typical metals generally present. Usually, the metalloids possess the form or appearance of metals, but are more closely allied to the non-metals in their chemical behaviour. The following elements are included in the metalloids: H, Te, Ge, Sn, Ti, Zr, As, Sb, Bi, V, Cb, Ta, Mo, W, and U."

Berzelius, in 1818, also thought Se was a metal due to its lustre. He subdivided the metals into two classes, those that are capable of forming acids, and those that act as bases: "I place selenium among the acidifiable metals near arsenic." (Trofast J 2011, Berzelius' discovery of selenium, Chemistry International, 33(5), p.16) I guess Dumas (1828) was still going by Berzelius's classification, and that by 1844, Dupasquier (among others) had worked it out.

Agricola (1546) may have considered Sb to a metal on the grounds that "when smelted, a certain portion be added to tin, a bookseller's alloy is produced from which the type is made that is used by those who print books on paper."

I don't know on what basis Pliny confused Sb and Pb. I believe he knew the first was brittle and the second malleable.

In 1658, when Glauber wrote that passage in Opera Chymica (1658), Co, Zn, Sb, and Bi were all considered to be semi-metals, due to being brittle. The ides of associating each of these imperfect "metals" to a planet was, alchemically speaking ... err ... daft.

"Half-metals or semi-metals were substances which resembled the "old" metals in color and density but which had differences in formability. After Georg Brandt's dissertation on the half-metals in 1735 and his discovery of cobalt, six semi-metals were known: mercury, bismuth, zinc, antimony, cobalt and arsenic. When new metals like molybdenum were discovered and prepared, they were often not malleable owing to the presence of impurities and because of that were called semi-metals." Enghag P 2008, Encyclopedia of the Elements, John Wiley & Sons, p. 596.

Sandbh (talk) 12:53, 8 January 2024 (UTC)

@Sandbh: Thanks for the lists: I see Friend is on the Internet Archive. I see Newth does not include Ge and Sb, and it's interesting that Friend considers many of the group IVB through VIB metals as "metalloids" on the grounds of their chemical behaviour. As you know, I would agree with Friend on that (especially for highly electronegative W, which doesn't even manage to form ionic halides). On the other hand, this rather seems to mean that the general idea of "metalloid" among pre-WW2 authors is not the same as the one we have now, and that it was by no means agreed that Ge, As, Sb, and Te were nonmetals then, although people thought B and Si were. Which raises my questions: did most people think Ge, As, Sb, Te were nonmetals around 1900, when it was more common to have only two categories (metals vs nonmetals)? And since the post-WW2 era is when three categories becomes common, is it really justified to consider most of these as nonmetals by default, when most authors nowadays would say that metalloids are something different from both metals and nonmetals? Moreover, doesn't the idea about "relatively low densities and predominantly nonmetallic chemistry" raise questions about Ti, V, and Zr that are all less dense than Sb? (All three are mentioned by Friend as being "more closely allied to the nonmetals" chemically; considering that TiCl₄ and VCl₄ are covalent molecular liquids at room temperature like SiCl₄, and that the Zr⁴⁺ aqua cation is so easily hydrolysed, he has a point!) On these grounds I think I'd be much happier if metalloids were given as a "sometimes" inclusion for comparison rather than as a default fourth category of nonmetals, more like the way elements like C, Al, and Se are treated in metalloid.

Regarding Pliny and Dioscorides, see the passages here. On the one hand Pliny distinguishes "male" and "female" antimony (probably stibnite and metallic antimony respectively); on the other hand, when describing the processing of stibnite, he calls the metallic reduction product lead (faex plumbosissima). Double sharp (talk) 13:32, 8 January 2024 (UTC)

@Double sharp: Thanks. I don’t know where the idea of "relatively low densities and predominantly nonmetallic chemistry" came from. The article refers to including metalloids for comparative purposes and due to their "relatively low densities, high electronegativity, and (nonmetallic) chemical behavior." Ti, V, and Zr have low EN. I’ve changed the text in the Types section so that it now refers to "three to four types", rather than "four". Is that OK? The article otherwise elsewhere mentions the sometimes nature of metalloids as nonmetals, at several points.

I don't know enough about the situation c. 1900.

Germanium has a record of being regarded as a poorly conducting metal, with its conductivity arising from impurities. AFAIK its status as a nonmetallic element was not sorted out until the 1930s(?) when the physics of semiconductors emerged. OTOH there is this:

"Germanium, Ge, a new nonmetallic[sic] element…" (Winkler 1886)

--- Winkler C (1886), Berichte der Deutschen Chemischen Gesellschaft, vol. 19, pp. 210–211

Arsenic and antimony have a long history of causing difficulties for classification science. The oldest quote I have for As is:

"Arsenic is in the main, however, an acid-forming element and plays the part of a non-metal in its compounds."

--- Schrader FC, Stone RW & Sanford S 1917, Useful minerals of the United States, Bulletin 624, United States Geological Survey, Washington

The oldest quote I have for Sb is:

"Antimony…is of more metallic appearance than arsenic, but, although it has some of the properties of the metals (lustre, electrical and thermal conductivity), in its chemical behaviour it is closely connected with arsenic and phosphorus…Bismuth…has no[sic] non-metallic characters and may be considered as a metal, as it forms no gaseous hydrogen derivative and its oxide has basic characteristics." (Molinari 1920, pp. 426, 792)

--- Molinari E 1920, Treatise on general and industrial inorganic chemistry, 2nd ed., J & A Churchill, London.

Mendeleev, however, regarded both As and Sb to be metals.

I suspect Te may have ended up with an "-ium" suffix due to it appearing to Müller (1783) to form a metallic alloy with gold, as AuTe₂, bearing in mind the limited understanding of time as to the distinction between metals and nonmetals.

Te was described by Mendeleev as forming a transition between metals and nonmetals.

The Pliny link seems reasonably clear as to the distinction between Sb and Pb: "The lees are recognized by being full of lead and they settle to the bottom of the mortars and are thrown away...But above all, it is essential to limit the amount of heat applied to it, so that it may not be turned into lead."

Stibnite can occur with galena (PbS) and that's what appears to be going on.

--- Sandbh (talk) 12:15, 9 January 2024 (UTC)

Let me rephrase my concern so that it's perhaps clearer. :) In metalloid, we have a clear break between elements that are considered metalloids nearly all the time, versus elements that are so considered only sometimes: the most often included among the "sometimes" elements is polonium at 49%. Well, you didn't consider it alongside the others, okay. But my question is: could you get even 49% of chemists to agree that metalloids are nonmetals? Note that I'm not asking "could you get them to agree that metalloids generally have nonmetallic chemical properties and all that". I'm asking "could you get them to agree that metalloids are a subcategory of nonmetals, and not a third category on the border zone that are neither metal nor nonmetal"? My impression of the literature is that you could not. Considering the precedent of metalloid, that suggests that metalloids should not be considered by the article as a normal inclusion into the nonmetals category, but as a sidelined "sometimes", something like how polonium or selenium is treated in Metalloid. So, I would much prefer the number of nonmetal categories to be three, with a caveat that metalloids are sometimes considered nonmetals as a whole, and that since people disagree about where exactly the metalloids end, even authors who think metalloids are an in-between class might annex some (but not all) of usual six into the nonmetals, e.g. Hawkes with metalloids = Ge-As-Se-Te and nonmetals including B and Si. And sure, it would probably be good to know when people stopped calling new metals "semi-metals". :) (At least, Lavoisier in 1789 was happy to list As and Sb among metals, but B as radical boracique is with the nonmetals, and Si is there as an earth alongside what would be Mg, Al, Ca, and Ba.)

I agree that our current understanding of metallicity is better than the past one, but if we are going to give some history, we should at least state how it evolved with greater completeness. No doubt, the understanding of semiconducting behaviour played a large role in figuring out what was going on with Ge and maybe Te.

Pliny seems to think that heating stibnite produces only Pb (and Dioscorides thought the same, according to the link I gave); Sb is not mentioned in this context. Note that in the process he describes, one is not actually trying to get the metal. Indeed, that's exactly what is not wanted: But above all, it is essential to limit the amount of heat applied to it, so that it may not be turned into lead. I think it's reasonable that he'd make a mistake identifying something he considered an unwanted waste product and hence did not really care about. Double sharp (talk) 09:25, 12 January 2024 (UTC)

@Double sharp: Thank you.

I don't know if 49% of chemists would agree metalloids are nonmetals. OTOH, I presume > 49% know that metalloids have a predominately nonmetallic chemistry. Per your suggestion, the article clarifies the "sometimes" nature of metalloids, in the following places:

Places in the nonmetal article re the odd nature of metalloids

Lede

A nonmetal is a chemical element that mostly lacks metallic properties. Seventeen [emphasis added] elements are generally considered nonmetals, though some authors recognize more or fewer depending on the properties considered most representative of metallic or nonmetallic character. Elements on the borderline further complicate the situation.

usually/always counted as a nonmetal

sometimes counted as a nonmetal [i.e. metallloids]

1 Definition and applicable elements

There is no precise definition of a nonmetal;[6] any list of such is open to debate and revision.[7] Which elements are included depends on the properties regarded as most representative of nonmetallic or metallic character.[n 3]

These fourteen elements are effectively always recognized as nonmetals:[7][8]

Hydrogen, Nitrogen, Oxygen, Sulfur

Fluorine, Chlorine, Bromine, Iodine

Helium, Neon, Argon, Krypton, Xenon, Radon

Three more are commonly called nonmetals, but some sources list them as metalloids:[9]

Carbon, Phosphorus, Selenium

The six most commonly recognized metalloids have relatively low densities and predominantly nonmetallic chemistry and are typically seen as intermediate between metals and nonmetals;[10] they are included in this article for comparison:

Boron, Silicon, Germanium, Arsenic, Antimony, Tellurium

In the periodic table, to the right of the metals, three to four types of nonmetallic elements can be recognized (proceeding from most to least nonmetallic):

the relatively inert noble gases;[110]

the notably reactive halogen nonmetals;[111]

the mixed reactivity "unclassified nonmetals", a set with no widely used collective name;[n 18] and

the generally unreactive[n 20] metalloids,[128] sometimes instead considered a third category distinct from metals and nonmetals.

The boundaries between these types are not sharp.[n 21] Carbon, phosphorus, selenium, and iodine border the metalloids and show some metallic character, as does hydrogen.

3 Types

The classification of nonmetals can vary, with approaches ranging from as few as two types to as many as seven…

In the periodic table, to the right of the metals, three to four types of nonmetallic elements can be recognized (proceeding from most to least nonmetallic)…

The greatest discrepancy between authors occurs in the metalloid "frontier territory".[130] Some consider metalloids distinct from both metals and nonmetals, while others classify them as nonmetals.[131] Some categorize certain metalloids as metals (e.g., arsenic and antimony due to their similarities to heavy metals).[132][n 22] Like the elements universally considered "nonmetals", metalloids have relatively low densities, high electronegativity, and similar chemical behavior;[128] they are included in this article for comparative purposes.[n 23]

5 History, background, and taxonomy

Metalloids came to be popularly regarded as intermediate elements despite it being known that they have a predominately nonmetallic chemistry. [This sentence recently rearranged by me]

Comparison of selected properties

The dashed lines around the columns for metalloids signify that the treatment of these elements as a distinct type can vary depending on the author, or classification scheme in use.

I count ten places in which the peculiar treatment of the metalloids is mentioned. The overall emphasis is on the seventeen elements generally recognised as nonmetals, with the six metalloids being mentioned as appropriate.

The metalloid article and nonmetal article work side-by-side. The first has a much narrower focus; the second has a broader focus due to the overlap of the predominately nonmetallic chemistry of the metalloids.

In response to your concerns I've add a paragraph to the Development of types section, explaining the status of B and Si, and what happened to Ge, As, Sn and Te.

How is the article now looking? --- Sandbh (talk) 05:52, 22 January 2024 (UTC)

@Double sharp, @Sandbh: Have the issues raised in this section been resolved? YBG (talk) 05:38, 17 February 2024 (UTC)

@YBG and Double sharp: I believe so. --- Sandbh (talk) 12:37, 17 February 2024 (UTC)

@Double sharp, have the issues raised in this section been resolved? YBG (talk) 12:12, 5 March 2024 (UTC)

@YBG and Sandbh: Sorry for forgetting to answer this. Yes, I think the section is OK now. Double sharp (talk) 15:39, 5 March 2024 (UTC)

Definitions & lists

resolved Sandbh (talk) 09:03, 8 March 2024 (UTC)

Consider the 2nd paragraph of § Definition and applicable elements:

• Current text: There is no precise definition of a nonmetal;[12] any list of such is open to debate and revision.[13] Which elements are included depends on the properties regarded as most representative of nonmetallic or metallic character.[n 2]
• Issue with current text: Many precise definitions exist.
• Proposed text: Many ways to define "nonmetal" have been discussed; none precise enough to determine all edge cases has gained general acceptance.[both refs] The elements listed as nonmetals depend on which properties are regarded as most representative of nonmetallic or metallic character.[same note]
• Issues with proposed text: Do existing refs support it? Where to place the refs? Is it WP:SYNTH?

Thoughts? ———YBG (talk) 14:49, 19 February 2024 (UTC)

I think the issue is that there is no "precise widely agreed definition". That is likely all that needs to be said. --- Sandbh (talk) 05:30, 20 February 2024 (UTC)

A side question that seems interesting but probably doesn’t enter in to determining content of the article:

• Do authors determine nonmetal lists based on their chosen definition, or do they consciously or unconsciously choose a definition based on the list desired?

——— YBG (talk) 14:49, 19 February 2024 (UTC)

@YBG: I suspect most authors don't have a chosen definition in mind apart from appreciating that nometals don't have predominately metallic properties. --- Sandbh (talk) 06:57, 23 February 2024 (UTC)

Might they have an unconscious assumption of how certain elements should be classified and evaluate particular definitions based on how it assigns those elements? YBG (talk) 02:54, 3 March 2024 (UTC)

@YBG: Probably most of those authors recall the limited or zero attention paid to metalloids from the textbooks they were exposed to in their youth. Probably they recalled that which elements were counted as metalloids, if at all, varied. Aside from my suggested quantitive definition in JChemEd, there is only one other quantitative textbook definition of metalloids that I know of. So, no, it’s very likely that the great majority of authors writing about metalloids flew by the seat of their pants. Either that or they parroted someone else’s work. — Sandbh (talk) 11:36, 3 March 2024 (UTC)

On a related subject, I think you could write an interesting journal article on the various single-property definitions listed in § Suggested distinguishing criteria. The article would be essentially an annotation of a huge table with one row for each of these properties and one column for each element, with the cells colored to show whether the definition classifies the element as a metal or nonmetal. A note or a different color could indicate that the element wasn’t yet discovered at the time. YBG (talk) 02:54, 3 March 2024 (UTC)

I intend to explore those single definitions in a chapter of the book I pm’d you about. — Sandbh (talk) 11:01, 3 March 2024 (UTC)

@Sandbh: I think we can close this section. YBG (talk) 16:29, 7 March 2024 (UTC)

Property comparisons

resolved Sandbh (talk) 09:07, 8 March 2024 (UTC)

Why is § Comparison of selected properties in the § History, background, and taxonomy section? These tables that compare the chemical and physical properties of metals and the 3+1 types of nonmetals would seem to be more appropriate either in the Chemical and Physical subsections of § General properties or else at the end of § Types. Thoughts? YBG (talk) 04:58, 17 December 2023 (UTC)

@YBG: It's at the end of the artice as feedback from a previous FAC or review was that the table represent too much "clutter" midway through the article, or words to that effect. --- Sandbh (talk) 04:50, 18 December 2023 (UTC)

That makes sense. My concern is that including them there makes that section seem like a coat rack of marginally related topics. But I don’t have a good alternative right now. YBG (talk) 05:08, 18 December 2023 (UTC)

Yes. In another sense, the article tends to flow from basic definitions and properties to more specific information about types, abundance, and historical background, in just five sections. This approach may help the reader see how current understanding and typology are rooted in historical developments and empirical comparisons. --- Sandbh (talk) 04:05, 20 December 2023 (UTC)

It still seems weird to have the properties split in two places in the article. Nevertheless, I can see how these two big tables could be intimidating if placed earlier in the article. Some time back I changed the section titles so there are no longer repeated section titles "Chemical properties" and "Physical properties". Instead the first sections are "Chemical/Physical properties of nonmetals" and "Chemical/Physical properties of nonmetals by type". I also added hyperlinking hatnotes so the reader can navigate between tables.

i think we can close this section YBG (talk) 22:29, 5 March 2024 (UTC)

Allotropes

resolved Sandbh (talk) 21:34, 8 March 2024 (UTC)

@Sandbh, @Double sharp: I have moved the brief mention of allotropes up earlier so that it can serve as a scoping statement describing which forms the article discusses. It also subsumes the hatnote about most stable form under ambient conditions. At the same time, I added a brief mention of hydrogen’s isotopes which seemed appropriate. I need you to verify that I listed the correct allotrope. I was not able to find information about iodine, so please add it to the list. YBG (talk) 16:57, 19 February 2024 (UTC)

@YBG: I feel there is now too much information up front. Allotropy is something that the general reader largely does not need to read about until later on. This is an aspect of the article that was criticised during a previous FAC round: too much detailed information too early on. Keep it simpler up front. A further unintended consequence is that the picture of shiny boron is now used twice and within close proximity. I will have a look at all of this and make some edits. Sandbh (talk) 05:28, 20 February 2024 (UTC)

@Sandbh: Fair enough. I’ve restored the list of standard forms as a note within the hatnote; that way it is accessible for the interested technical reader without cluttering things for the more general reader. Some possible further changes:

1. Move the list of standard allotropes out of the current note into the allotrope section and hyperlink it from the current note. I’m leaning to doing this.
2. Deal appropriately with protium, either (a) leave it in the note, separate from the standard allotrope hyperlink, or (b) move protium into list of standard forms by expanding the allotrope section into alternate forms by including isotopes with significant property differences (which may just be H). I’m leaning to (b).
3. Move this hat note to a better position. The present placement doesn’t seem like any of the standard uses of a section hatnote, but I don’t have a good alternative.

Thoughts on any of these ideas?

——— YBG (talk) 05:55, 21 February 2024 (UTC)

I don't see the point in including isotopes. Yes, the isotopes of H and He show extreme differences that we don't see in any other elements' isotopes, but it does not affect their metallicity at standard conditions. Only at the extreme high pressures needed to metallise them do we probably see a difference (protium and deuterium should have noticeably different metallisation pressures), and these are not really relevant for the article (though I personally would like to learn more about the high-pressure situation!).

I also don't really see the point of listing all allotropes individually. What I do see the point of doing is noting up front the reason why we consider the situation at ambient conditions: that they differ in other conditions. In other words, I'd rather note very early on that the classification of an element as a metal or as a nonmetal is dependent on conditions, because physically speaking these change at high pressure. The demetallisation of Na, along with other changes in EN at high pressure, could be adduced as a brief explanation. This would help contextualise some other things in the article, like the Xe intermetallics in footnote 33 and the He and Ar compounds in footnote 59, that are dependent on high-pressure conditions. Double sharp (talk) 11:00, 23 February 2024 (UTC)

@Double sharp and YBG: The footnote in the middle of the hatnote has been relocated to the end of the hatnote. I've adjusted the listing of stable forms, including removing the isotope reference. I've added a footnote to the end of the Definitions and applicable elements section to cater for temperature and pressure variations. I believe this thread may now been addressed. --- Sandbh (talk) 23:01, 23 February 2024 (UTC)

Ok, it appears to me that there is no need to say anything about isotopes.

One thing, however. I believe that "ambient conditions" should be wiki linked, but I’m not sure to what. @Sandbh, can you take care of that?

That being done, I’m ready to close this section. YBG (talk) 16:25, 7 March 2024 (UTC)

@YBG: I have linked ambient conditions to ambient temperature and to ambient pressure. — Sandbh (talk) 09:00, 8 March 2024 (UTC)

I tweaked it slightly. YBG (talk) 15:39, 8 March 2024 (UTC)

If it’s ok by you, go ahead and cot/cob this section. YBG (talk) 15:52, 8 March 2024 (UTC)