# Wikipedia talk:WikiProject Chemistry

WikiProject Chemistry (Rated Project-class)
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## Removal of Chemistry Portal from the template, put it back

Just because the portal has been abandoned does not mean that the portal is useless. There is valuable information on the portal, especially if a person is interested in the quickly seeing the vocabulary for a field and not just reading an encyclopedia article. Unless the plan is to remove the PORTAL parameter from all of the WikiProject templates, it should be put back. Leave it to the reader to judge the usefulness of the information on the portal page. Use case example: a person is learning a foreign language and needs to learn the most important words in Chemistry. The Chemistry portal page will give them that information where the Chemistry article will not.

Portals are setup to do rotations of articles automatically. As long as the choice of articles is contained in the Top or High category, if code is written to randomly choose an article from one of those two categories by just grabbing the introduction automatically (TextExtracts), it does not need to be maintained in order for it to work. Zzmonty (talk) 07:55, 25 July 2018 (UTC)

## Debate on the correct values for the pKa of water and hydronium

A number of Wikipedia articles concerning acids (e.g. strong acids, hydronium, pKa, etc.) are not in agreement when discussing the pKa of water and hydronium. This inconsistency reflects an ongoing "debate" on which standard state should be used when calculating the values. The most recent (and comprehensive) papers to discuss this topic are:

J. Chem. Educ., 2017, 94 (6), pp 690–695 DOI: https://doi.org/10.1021/acs.jchemed.6b00623
Helv. Chim. Acta, 2014, 97 (1), pp 1-31 DOI: https://doi.org/10.1002/hlca.201300321

Briefly, depending on the mathematical convention used for standard state, the pKa for water is listed as either 14 or 15.7 and the pKa for hydronium is listed as either 0 or -1.74. When using the standard and agreed upon conventions of thermodynamics, the values of pKa are 14 and 0 for water and hydronium, respectively. Unfortunately, however, an overwhelming number of standard textbooks (introductory chemistry and organic chemistry) have relied upon using a non-standard convention that results in the values of 15.7 and -1.74. Depending on the article (and sometimes even the section of article), Wikipedia currently uses a combination of the values. I propose that we begin to clear up this issue by making the articles more consistent. This is a big undertaking since these values are likely to be found in a large number of individual articles. Furthermore, I would like to achieve at least some consensus among editors prior to taking this on. Thanks! JCMPC (talk) 16:57, 29 April 2018 (UTC)

Indeed, even Properties of water used to have 15.7 as the pH in the infobox until I changed it (among my early edits, actually) and why I put two references for the pKa and a note. Investigation into the history reveals that from ~2006 (basically when it was inserted), till 2016 when I changed it, it was 15.7, which is somewhat disturbing IMO. Anyhow, I'd definitely say that changing instances of 15.7 to 14 would be good to do. Galobtter (pingó mió) 17:27, 29 April 2018 (UTC)
I have a feeling that, until authors of organic chemistry textbooks switch to the standard thermodynamic convention, the value will likely be edited back and forth for some time on Wikipedia. Are any other editors willing to help out on making the switch to make articles more consistent? JCMPC (talk) 14:37, 5 May 2018 (UTC)
It looks to me like you guys are missing a factor in your argument. A standard convention does not reflect the real value of something. It is simply the chosen value for making empirical and theoretical coparrisons. For example, just because the IUPAC standard convension for ambient temperature and pressuren is 25 degrees Celcius and 100 kPa, does not mean that the location that you are in has those conditions. i.e. Just because some institution decides that the standard convension for the pKa water and hydronium is 0 and 14, does not make it so in reality. I strongly suggest that if you insist on retaining both sets of pKa values, that you make that non-standardised ones the primary set. Plasmic Physics (talk) 23:02, 5 May 2018 (UTC)
Yes, it is widely known that the definition of any standard state is arbitrary and is, in a great many cases, corresponds to an idealized value that is not even physically realizable (e.g. gaseous water does not exist at a partial pressure of 1 bar at a temperature of 300 K but we can still tabulate enthalpies of formation for water under those conditions). The advantage of using the widely accepted definition of thermodynamic standard states is not that these values are correct under all conditions (because they're not), but that they make it easier to communicate measurements and ideas. One of the main points of classical thermodynamics is to determine how factors such as pressure and temperature affect quantities such as equilibrium constants. As long as a standard value is known, it is possible to convert it to another set of conditions. So I guess I don't see the advantage to using non-standardized versions as the primary set of values. Wouldn't this be like supporting a non-standard definition of the meter? Sure one could always come up with a conversion factor to convert between standard and non-standard definitions of the meter, but why go through all the trouble when we can all just use the same definition? JCMPC (talk) 01:00, 17 May 2018 (UTC)
That is not a very accurate comparison - there is no notable use for a non-standard meter outside of discussions of the notion, whereas real, non-normalised pKas are useful to the entire field of analytical chemistry. It is simply not appropriate to use standard pKas within high precision fields. Furthermore, the ChemBox, as it is named, is first and foremost intended to collate chemical information before general thermodynamic information; and yes, I realise that there is some overlap, which is why I suggest the ordering of the pKas if both are included. Plasmic Physics (talk) 05:19, 17 May 2018 (UTC)

The value -1.76 is simply -log10(55.5) . It has nothing to do with acid dissociation. 55.5M is the molarity of pure water.

The criterion for classifying an acid as "strong" is that it is fully dissociated in solution. The following table shows the calculated degree of dissociation of a monobasic acid, AH, at a concentration of 1M, as a function of pKa. Dissociation will be greater, the lower the concentration of the acid.

pK % dissociation
1 27
0.5 43
0 62
-0.5 80
-1 92
-1.5 97
-2 99

This shows that, in general, an acid may be classified as "strong", if its pK value is less than about -2. That this value is close to -1.76 is purely fortuitous. Petergans (talk) 21:27, 13 August 2018 (UTC)

## What is a metal in chemistry?

Is there a chemistry-based definition of a metal? I suspect not. If there was one I presume there would be no argh-bargy about where to draw the line of demarcation between metals and non metals, at least within the discipline of chemistry. Sandbh (talk) 07:57, 8 May 2018 (UTC)

There are several definitions, ranging from the simple (anything shiny and conductive) to the complex (unfilled electronic band at the fermi level). The problem, as your question points out, it in applying a binary ‘is/isn’t’ definition to what is in reality a gradient. Where you put the line is somewhat arbitrary (where does blue end and green begin?). In terms of Wikipedia, how/where is this a problem?--Project Osprey (talk) 08:54, 8 May 2018 (UTC)

Thank you.

I was interested in definitions based on chemical properties instead of physical properties such as shininess or conductivity. For example, simple cation formation or having at least one basic oxide. The challenge is that there are some metals like tantalum or tungsten that meet neither of these criteria. Just what is it, from a chemist's point of view, that warrants classifying Ta and W as metals?

There is not much of a gradient, as I understand it, in distinguishing between metals and nonmetals. The consensus of the literature classifies B, Si, Ge, As, Sb, and Te as metalloids. And Wikipedia classifies At as a metalloid, on the basis of its apparent properties, noting it has been predicted to have a fully metallic band structure. So, apart from H, elements to the left of the metalloids in the periodic table are metals.

The context for my question is a desire to improve our metal article. It seems odd that there does not seem to be an inclusive definition of a metal based purely on chemical properties. Sandbh (talk) 10:38, 9 May 2018 (UTC)

────────────────────────────────────────────────────────────────────────────────────────────────────

### Metallic bonding

In that case I'd define a metal (somewhat cyclically) as anything which engages in metallic bonding. That is the chemical phenomenon behind most of their physical properties. Sadly the metallic bonding page needs quite a bit of work. --Project Osprey (talk) 10:58, 9 May 2018 (UTC)

That would be awkward since H is capable of forming alloy-like hydrides, featuring metallic bonding, with some transition metals. I'm not pretending this is an easy question—I don't yet see how to do it without including at least one physical property like conductivity. Sandbh (talk) 13:03, 9 May 2018 (UTC)

I don't think that's a strong argument. I imagine most elements can be alloyed but that doesn't mean that they're metallic in their own rights. Hydrogen is not a metal under standard conditions, that's obvious just by looking at it. That you can force it into displaying metallic properties is besides the point. --Project Osprey (talk) 13:31, 9 May 2018 (UTC)
Well, it seems like we'd have to add another criterion to the definition so as to exclude H, given it is capable of metallic bonding. You seem to be inferring that this would be a physical property like appearance. The only extra chemical property I can think of is to specify an ionisation energy less than or equal to that of mercury, but this also seems slightly circular. Sandbh (talk) 05:42, 10 May 2018 (UTC)
@Sandbh: I think the intent was to look at the pure element – which almost recreates our dividing line perfectly (if you add astatine as a metal), but excludes bismuth as α-Bi is isostructural to α-As and α-Sb. Double sharp (talk) 14:56, 9 May 2018 (UTC)
I have some reservations about relying on the wooly concept of a "metallic bond". That aside, the literature consensus is to treat Bi as a metal largely on the basis of its basic trioxide, the structure of which is also more like that of a typical metallic oxide unlike the molecular oxides of Sb and As. So, the definition would become something like, "In the periodic table, any element which (a) features a structure characterised by "metallic" bonding; or (b) has a basic oxide, is classified as a metal." Sandbh (talk) 12:08, 10 May 2018 (UTC)
I presume there is some notion of a standard temperature and pressure for this, because otherwise just about everything should be metallisable. But then at 0 °C and 1 bar (IUPAC standard temperature and pressure), α-Sn is the stable allotrope (which is certainly not characterised by metallic bonding), and both SnO and SnO2 are amphoteric. Double sharp (talk) 15:08, 10 May 2018 (UTC)
Thank you. Yes, the definition I had in mind applies at IUPAC's SATP i.e. standard ambient temperature and pressure or 25 °C and 1 bar of pressure. I don't know, but I suspect SATP is more useful in considering the properties of the elements than STP given the complication caused by the reversion of white tin to grey tin at STP.
More importantly perhaps is the question of what we mean by a structure characterised by metallic bonding. Grey tin has the diamond structure but is also a semimetal in the physics based sense, even though it behaves like a semiconductor. As a semimetal there is presumably some vestige of metallic bonding. Then again, we can always say metallic bonding means "full value" metallic bonding therefore semimetals (physics) are not counted. In which case the suggested definition based on chemical properties would work. Sandbh (talk) 08:32, 11 May 2018 (UTC)
I'm confused now. Are we talking about 'metal' as in a state of matter (metallic state), or is this about metallic elements?--Project Osprey (talk) 09:05, 11 May 2018 (UTC)
Metallic elements. Sandbh (talk) 02:21, 12 May 2018 (UTC)
If we count semimetals, then carbon is a metal; if we exclude semimetals and demand basic oxides, then grey tin is not a metal while white tin is. I find the former distasteful for obvious reasons and the latter distasteful since there is no chemical change involved. Using cation formation leads to a more pleasant outcome; although I'm persuaded that this puts antimony on the metallic side, I don't find this problematic as it is electropositive enough to form compounds which can be considered salts. (I will have to look up germanium chemistry, though.) Double sharp (talk) 09:30, 11 May 2018 (UTC)
────────────────────────────────────────────────────────────────────────────────────────────────────

### Sb3+ and Ge2+ cations

The proposed definition of a metal applies at SATP. It does not matter if, at temperatures lower or higher than 25 °C, the metal in question becomes a semimetal, semiconductor, or an insulator. AFAIK there is no simple Sb3+ cation. The closest I have seen in the literature is [Sb(H2O)4(OH)2]+. The compound Sb8(GaCl4)2, which contains the homopolycation, Sb82+, was also prepared in 2004. The status of Sb "salts" was strongly criticised by Axiosaurus on the metalloid talk page. Evidence for the existence of a simple Sb cation, or a genuine Sb salt, appears to be lacking. Sandbh (talk) 12:40, 12 May 2018 (UTC)

@Sandbh: (since I think these papers would interest both of you; incidentally, , do you know where I could find those papers suggesting the existence of Sb3+ in perchloric acid media, since that's the way the standard reduction potential for Bi3+/Bi was measured?):
Here are some quotes on Sb3+:
"Other studies into the speciation of antimony(III) include one on the solubility of stibnite [Sb2N3] in HCl–NaCl solutions conducted by Ovchinnikov et al. (1983). Their data suggests that chloride complexing of trivalent antimony is unimportant in the temperature range 180 to 300°C (although these authors concluded differently). In sulfur free systems, antimony compounds hydrolize to form antimonous acid SbOH0
3
, which predominates over a wide range of pH. In the acid range, Sb(OH)+
2
is formed, and only at very high acidities is the free Sb3+ ion stable." (Ralf E. Krupp, 1988: "Solubility of stibnite in hydrogen sulfide solutions, speciation, and equilibrium constants, from 25 to 350°C"; 10.1016/0016-7037(88)90164-0)
"The accurate value of the standard potential of antimony against Sb3+ ions is not known since single Sb(III) ions exist in very small concentration in aqueous solution. Solubility determinations of Sb4O6 in HClO4 indicate [4, 5] that dissolved trivalent antimony is mainly in the form SbO+ (in the pH range 0 to 1)." (Past Vello's section on Sb in Standard Potentials in Aqueous Solution, 1985; this suggests to me that you need to go to negative pH to have a chance of seeing Sb3+).
Ab initio simulations support the existence of a Sb3+ aqua ion, although the above observations make it quite clear that you will not see any experimental evidence for it until the pH goes really low. See for example 10.1016/j.cplett.2011.05.060, which discusses Sb3+ along with the stable trivalent cations (Al3+, Fe3+, V3+, Ir3+, La3+, and Ce3+); I presume they are considering hydrolysis only from the metal cation itself, rather than from the acidity of the medium. The ion appears to have an interesting structure: "A completely different system is the main group ion Sb(III) with its lone electron pair destabilising the hydrate [38]. As this electron pair occupies a considerable space, it induces the formation of two different hydration hemispheres, one with four tightly bound ligands at a distance of 2.2 Å and another one on the opposite side with four much more loosely bound water molecules located 2.7 Å far from the ion. The latter are responsible for frequent exchanges between first and second hydration sphere, leading to an MRT value of 6 ps for first shell ligands and a very low MRT (< 2 ps) for those of the second shell, which is equally unsymmetric as the first shell, with 5 plus 8 ligands."; see 10.1021/ic901737y for more about this structure, which is due to the large space occupied by the 5s electron pair on Sb3+; Sn2+ has a similar issue. This is in stark contrast to As3+ which hydrolyses pretty much instantly; the article says "In the case of this smaller group V cation, the effect of the lone pair is apparently strong enough to cause an immediate hydrolysis, while in the heavier analogue Sb(III) it only leads to a strongly distorted hydration structure (vide supra)." Similar ions are Ge4+, Sn4+, and Pb4+ which hydrolyse on the picosecond scale. The final stable forms appear to be As(OH)2+ (there seems to be a typo in the article), Ge(OH)3(H2O)+, and hexacoordinate and heptacoordinate species of the form M(OH)+
aq
for Sn and Pb respectively. (OTOH, Zr4+, Hf4+, Ce4+, and U4+ are confirmed to be real stable tetrapositive cations).
I will also add a word about Ge2+. It seems to be capable of existence (10.1002/jcc.21315) based on computational studies, and have a similarly distorted structure, again like Sn2+ and Sb3+ due to the lone pair. Given this, I think I might even dare to call germanium a metal as well as antimony. At least for the s- and p-block metals, it seems to be a sound criterion to demand aqueous cation formation; the d-block metals seem to require a somewhat different treatment. Double sharp (talk) 16:41, 12 May 2018 (UTC)

thank you Double sharp for those sources.

I now think too much significance is being attached to aqueous cation formation for As?, Sb, and Bi (and Ge). The species concerned seem to found only in highly acidic media, perhaps requiring negative pH in the case of Sb. I tend to be reminded of the claim that Hg was a transition metal based on the purported existence of Hg(IV) even though, as Jensen noted, the experimental conditions were quite extreme. In a similar vein, I'd regard the presence of Ge?, As?, Sb, and Bi aqueous cations as being too marginal to warrant classifying any of these elements as metals.

The original proposed definition stands up reasonably well i.e. "In the periodic table, any element which (a) features a structure characterised by "metallic" bonding; or (b) has a basic oxide, is classified as a metal." While Bi comprises covalently bonded atoms stacked in layers, its basic oxide is the starting point for most Bi chemisty. Sandbh (talk) 10:41, 13 May 2018 (UTC)

@Sandbh: Is Bi2O3 really completely basic, though? It's definitely more basic than Sb2O3, but Bi2O3 will dissolve in warm and very concentrated KOH.
Anyway, I don't agree that these species are irrelevant just because the unhydrolysed forms only occur at very low pH (except for As3+, which I agree does not exist as an aqua complex). Such a criterion would also exclude Pb2+, which doesn't even appear in the E–pH diagram for Pb species in The Aqueous Chemistry of the Elements even though it goes down to pH −1; Sn2+ is in a similar position, though it is called that in that book for simplicity. Yet I think we all would agree that tin and lead are metals. There does seem, however, to be a difference between elements that form and elements that don't form aqueous cations that is observable in chemistry: looking at Greenwood and Earnshaw, as well as 10.1002/jccs.196400020 for Ge(ClO4)2, it appears that GeII, GeIV, SbIII, BiIII, and PoIV form acidic oxoacid salts (with scare quotes possibly added), while AsIII, SeIV, and TeIV only form basic ones. Since Te also forms the Te(OH)3+ cation, simply relaxing the criterion to allow all incomplete hydroxy complexes doesn't seem to give the desired result (noting the dangers of this), since Te seems quite clearly to be closer to nonmetals than metals (it acts much like Se); requiring aqua cations to form seems better. We all have no hesitation talking about Tl3+, Sn2+, Pb2+, and Bi3+ even if those specific species rarely appear, because they are starting points of hydrolysis and they actually exist; why then should we not allow in Ge2+ and Sb3+? Double sharp (talk) 12:56, 13 May 2018 (UTC)
It should probably be noted that various nonmetals like iodine and sulfur can form what might be considered simple cations in some nonaqueous media. OrganoMetallurgy (talk) 13:12, 13 May 2018 (UTC)
P. B. Saxena has made some interesting comments about I+ and I3+ cations in pp. 112–118 of his Chemistry of Interhalogen Compounds (link). One argument he puts in support of his case is that many iodine compounds liberate iodine at the cathode when electrolysed in their molten or aqueous states, such as ICl, IBr, ICN, INO3, I2SO4, and so on. I must confess I'm not terribly convinced by some of this, though; for example, indeed ICl acts as a strong electrophilic iodinating reagent, but is a bare I+ cation really formed? BTW radon also forms simple Rn2+ cations in nonaqueous media; Greenwood and Earnshaw indeed mention cations of S, Se, Te, Cl, Br, and I formed in sufficiently oxidising solvents (e.g. oleum), but these are all polyatomic cations AFAIK, not like the simple cations of metals we were previously discussing. Double sharp (talk) 14:14, 13 May 2018 (UTC)
That's not what I was referring to. Rather I'm talking about stuff like Bis(pyridine)iodonium(I) tetrafluoroborate which is essentially pyridine solvate a salt of the I+ cation and the sulfur compounds discussed this doi:10.1021/ic1012582 article. They may require ligands for stability, but so what? I think those sorts of compounds (and there are many other kinds I could mention if anyone's interested) have been rather artificially considered a separate class of compounds from metal complexes. OrganoMetallurgy (talk) 17:59, 13 May 2018 (UTC)
Oh, I see. Yes, I agree that the distinction is rather artificial. Please do mention some more; I'd be interested in seeing how many of the nonmetals can be roped into doing something like this! ^_^ Double sharp (talk) 23:43, 13 May 2018 (UTC)
It seems that phosphorus, arsenic, antimony, and bismuth can all form bipyridine complexes doi:10.1039/C5SC02423D and sulfur, selenium, and tellurium form complexes with diiminopyridine doi:10.1021/ja9073968 and bromine and iodine both form bis pyridine complexes. --OrganoMetallurgy (talk) 22:34, 17 May 2018 (UTC)
Great, thank you so much for these examples! So in groups 15 through 17 only the strongest nonmetals N, O, F, and Cl remain unconquered in our lists so far. Double sharp (talk) 23:43, 17 May 2018 (UTC)

Anyway, I think the case of Sb(H2O)83+ is rather different from that of HgIV. The latter, if it exists at all, only appears in one compound at extreme conditions and does not illuminate anything else about Hg chemistry, which is resolutely that of a post-transition metal; so it is not terribly important for classification, unlike what is expected for Cn. But Sb3+ can be considered the starting point of hydrolysis that leads to Sb(H2O)4(OH)2+ and thence to Sb(OH)3; given that Sb has the ability to form "salts" formally involving a simple Sb3+ cation, like Bi, Po, and At but unlike As, Se, and Te (which only form basic salts), thinking of this cation as a starting point does seem to help understanding Sb chemistry even if it itself only appears at extreme conditions. I would say much the same of the cations Tl3+, Sn2+, Pb2+, Ce4+, Zr4+, and Hf4+. On the other hand, since As2O3 is a predominantly acidic oxide, and AsIII appears to quickly hydrolyse all the way to As(OH)3 (arsenious acid) in water, I would agree that thinking of As3+ is unhelpful.

When it comes down to it, all metals have a nonmetallic side (even caesium forms alkalides) and all nonmetals have a metallic side (even helium has a few similarities to beryllium), and especially around the metalloid line a binary distinction is difficult to maintain. We are not saying that antimony is wholly metallic or wholly nonmetallic; both statements are nonsense. To the extent that the question "is Sb a metal or not" makes sense, it must be asked in terms of which one gives a better first-order understanding of what one might expect of its physical and chemical properties. Since +3 is antimony's predominant oxidation state, in which Sb forms a cation and has an amphoteric oxide, I think it is less misleading to call it a metal with caveats than a nonmetal with caveats. The approach of looking at the most stable oxidation state in the p-block incidentally calls B, Si, Ge, As, and Te nonmetals, Sb a metal, and is agnostic on At given that At3+ has not yet been found AFAIK (although At+ and AtO+ being known suggests to me that it is a possibility). (Ge ends up on the nonmetal side because it forms a cation and has an amphoteric oxide in its unstable +2 oxidation state, and does neither in its stable +4 state.) Double sharp (talk) 06:04, 14 May 2018 (UTC)

Hmm, 10.1021/jp3099413 shows that even AtO+ is hydrolysed to AtOOH already around pH 2, so if At3+ does exist it must be at really low pH again. So I think I'd rather amend it to include all oxidation states found in species that actually appear on the element's E–pH diagram, so that astatine qualifies as a metal by virtue of the At+ cation. OTOH, Ge2+ would still not qualify germanium as one. Double sharp (talk) 08:28, 14 May 2018 (UTC)

Earlier you wrote, "Is Bi2O3 really completely basic, though? It's definitely more basic than Sb2O3, but Bi2O3 will dissolve in warm and very concentrated KOH." In his Treatise on Inorganic Chemistry (1956 p. 677), Remy wrote, "The insolubility of bismuth oxide in dilute alkalis, as compared with the amphoteric oxides of arsenic and antimony, marks it out as being definitely a basic oxide." That seems to be the explanation then for regarding bismuth oxide as being basic. So, at this stage, the original proposed definition based on having "metallic" bonding or having a basic oxide appears to still hold. Sandbh (talk) 06:01, 15 May 2018 (UTC)

### Apparent absence of chemical properties

────────────────────────────────────────────────────────────────────────────────────────────────────I would say that there isn't really any chemical properties that define metals. They do tend to have lower electronegativity than nonmetals, but there are exceptions. As far as I'm aware, in the context of chemistry, a metal is a element that in its pure form, under standard conditions, is considered metal ( elements that are considered metalloids are sometimes also included), based on its physical characteristics. Or alternatively to the electrical properties of a substance. OrganoMetallurgy (talk) 18:53, 11 May 2018 (UTC)

I was going to say I agreed with you as there were no chemical properties that appeared to be common to all metals. The fall back then becomes physical properties. However, I now tend to think that any element which…
• can form a simple cation in aqueous solution; or
• has a basic oxide; or
• adopts multiple oxidation states differing by one, and forms coloured compounds…
merits being classified as a metal.
I could be wrong but I believe this chemistry-based definition covers all the elements commonly counted as metals. No need to invoke any physical properties (I suspect the coloured compound criterion could be dropped). Sandbh (talk) 12:32, 15 May 2018 (UTC)
And what if we think here in terms of 'if we take a piece of metal and we react it vs. if we take a piece of non-metal and we react it, do we know reactions that distinguish the metal from the non-metal (as in a non-true example: 'metals dissolve in acids under evolution of hydrogen, non-metals do not dissolve in acids under evolution of hydrogen' - noting that some metals do not dissolve in acids (in that way))? --Dirk Beetstra T C 13:04, 15 May 2018 (UTC)
Agreeing with Dirk, I wonder about where the above discussion is nudging toward. In my institution's inorganic courses, we don't dwell on defining a metal ion, transition metal (the Zn issue), a lanthanide (the lanthanum issue), a main group element (Zn again), a metalloid (gray vs red Se), an organometallic cmpd (is Mo(CO)6 organometallic?), etc. For bulk metals, we note that the electrical conductivity of metals follows a 1/T relationship whereas semiconductors go the other way. On the other hand for an encyclopedia, we gotta say something. I just recommend flexibility.--Smokefoot (talk) 13:46, 15 May 2018 (UTC)
I think that in practice, the real definition of a metal just depends on whatever is most convenient at the moment. For those elements on the borderlines, it may sometimes be useful to include them as metals, and sometimes useful to exclude them. It's just that when considering metals is not the main point, and we're still colouring elements by metallicity on a nice periodic table graphic in one corner or at the bottom, we need to pick some defaults, and they might as well be the least misleading defaults to the novice who takes those colours at face value. That does not in any way stop us from changing things around if the context makes it reasonable to do so, as you say. Double sharp (talk) 15:31, 15 May 2018 (UTC)
@Sandbh: Doesn't this definition classify chlorine as a metal if taken literally? Chlorine forms ClF3, ClO2, and ClF5, which have Cl in the +3, +4, and +5 states respectively (differing by one). ClO2 is a yellowish-green gas and hence meets the colour requirement. Double sharp (talk) 04:57, 16 May 2018 (UTC)
10.1021/ed056p712 agrees with this pessimistic view, BTW. It suggests that metals can be distinguished by hardly ever assuming negative oxidation states, but we all know that gold means that this is not a criterion but a guideline. It also mentions that the metals become more nonmetallic in their properties as their oxidation state is increased (which is one reason for the very nonmetallic chemical behaviour of some of the 4d and 5d metals, for which the lower and more metallic oxidation states are unstable). It suggests high electrical conductivity in all three dimensions as a distinguishing physical property, but that approach would have us considering arsenic as a metal. Double sharp (talk) 15:28, 17 May 2018 (UTC)

Here's an update of the suggested definition of a metal, based on chemical properties:

Any element which…

* forms a simple cation in aqueous solution; or
* has a basic oxide; or
* uses d or f electrons in chemical bonding…

merits being classified as a metal.


Sandbh (talk) 10:25, 18 May 2018 (UTC)

@Sandbh: While I cannot think of anything that fails this definition at present that I think you can reasonably consider a metal, I dislike how it essentially rules the d- and f-block elements as metals by fiat (I guess adding the g-block elements once they are discovered). There must be something else that can be pointed to to support their metallicity. There are s-block metals and nonmetals, and p-block metals and nonmetals, so I have a hard time believing that block membership proves metallicity by itself. If it so happens that all d-block and f-block elements are metals (which I agree with), great, but I don't think we can declare it as a postulate. As Bertrand Russell wrote, "The method of 'postulating' what we want has many advantages; they are the same as the advantages of theft over honest toil." Double sharp (talk) 15:26, 22 May 2018 (UTC)

The challenge is how to cater for metals that don't form simple cations namely Zr, Hf; Nb, Ta; W; Tc; and Os. The first four of these form interstitial (metallic) hydrides. The only suitable chemical property I can see for W, Tc and Os is their capacity to exist in more than eight integral oxidation states. So that would give:

Any element which…

* forms a simple cation in aqueous solution; or
* has a basic oxide; or
* forms an interstitial hydride; or
* can exist in more than eight integral oxidation states…

merits being classified as a metal.


The capacity to form an interstitial hydride, as I understand it, is partly related to the existence of a metallic lattice, so I'm OK with that criterion.

The capacity to exist in more than eight integral oxidation states is less satisfactory because it isn't immediately clear why it's associated with metallicity. Still, it's an improvement on the former definition. Thoughts? Sandbh (talk) 01:27, 1 July 2018 (UTC)

After further thinking it's probably more helpful to flag the anomalies and note why the elements concerned are still regarded as metals. Like so:
Metal. An element which forms a simple cation in aqueous solution, or which has a basic oxide, or an interstitial hydride. Tungsten, technetium, and osmium exhibit none of these properties but are nevertheless classified as metals in light of their shared similarities with some other metals. These similarities include the capacity to exist in multiple oxidation states usually differing by 1, the formation of coloured solutions in water, and the formation of magnetic compounds. Sandbh (talk) 03:20, 21 July 2018 (UTC)

### Metal article lede construction

────────────────────────────────────────────────────────────────────────────────────────────────────One approach (which I think should be almost mandatory for most articles), is to build the lede on major (WP:TERTIARY) sources (not the damn OED). What are the "bibles" on metals? Get them and rely on them. As it stands, readers are force-fed these lame sources at the first five references:

• 1) μέταλλον Henry George Liddell, Robert Scott, A Greek-English Lexicon, on Perseus Digital Library
• 2) Oxford Dictionaries
• 3) Encyclopædia Britannica
• 4) John C. Martin. "What we learn from a star's metal content". New Analysis RR Lyrae Kinematics in the Solar Neighborhood. Retrieved September 7, 2005.
• 5) BEC. "Physicists Achieve Early Stages of a New, Solid State of Hydrogen". sciencealert.com. sciencealert.com. Retrieved 7 January 2017.

--Smokefoot (talk) 13:50, 9 May 2018 (UTC)

The metal article is a challenge. AFAIK there is no global bible that deals with all aspects of metals. The subject seems to be so big that what bibles there are only (largely) deal with either the chemistry, structures, metallurgy, physics, or engineering aspects of metals. So, to some degree, one is forced to fall back on the most general of sources like the OED or Britannica in order to give the broadest possible description of a metal. Then drill down into the more specialised sources, like the lede currently does with astronomy. That aside, I do agree that even just the lede could be improved. Sandbh (talk) 01:25, 12 May 2018 (UTC)

## Deletion: Fine electronic structure

I just proposed the article fine electronic structure for deletion Wikipedia:Articles for deletion/Fine electronic structure. I tried to rescue the article before as I thought I could learn a little about spin-orbit and other corrections to the band structure of solids. The doubt about the subject is if it is related to the specific details of general matter (atoms, molecules, solids) or just solids. Maybe an expert here could give an insight. Also look at the article as it was before: [1] --MaoGo (talk) 09:05, 18 May 2018 (UTC)

## Facto Post – Issue 12 – 28 May 2018

Facto Post – Issue 12 – 28 May 2018

### ScienceSource funded

The Wikimedia Foundation announced full funding of the ScienceSource grant proposal from ContentMine on May 18. See the ScienceSource Twitter announcement and 60 second video.

A medical canon?

The proposal includes downloading 30,000 open access papers, aiming (roughly speaking) to create a baseline for medical referencing on Wikipedia. It leaves open the question of how these are to be chosen.

The basic criteria of WP:MEDRS include a concentration on secondary literature. Attention has to be given to the long tail of diseases that receive less current research. The MEDRS guideline supposes that edge cases will have to be handled, and the premature exclusion of publications that would be in those marginal positions would reduce the value of the collection. Prophylaxis misses the point that gate-keeping will be done by an algorithm.

Two well-known but rather different areas where such considerations apply are tropical diseases and alternative medicine. There are also a number of potential downloading troubles, and these were mentioned in Issue 11. There is likely to be a gap, even with the guideline, between conditions taken to be necessary but not sufficient, and conditions sufficient but not necessary, for candidate papers to be included. With around 10,000 recognised medical conditions in standard lists, being comprehensive is demanding. With all of these aspects of the task, ScienceSource will seek community help.

To subscribe to Facto Post go to Wikipedia:Facto Post mailing list. For the ways to unsubscribe, see below.
Editor Charles Matthews, for ContentMine. Please leave feedback for him. Back numbers are here.
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## WikiProject collaboration notice from the Portals WikiProject

The reason I am contacting you is because there are one or more portals that fall under this subject, and the Portals WikiProject is currently undertaking a major drive to automate portals that may affect them.

Portals are being redesigned.

The new design features are being applied to existing portals.

At present, we are gearing up for a maintenance pass of portals in which the introduction section will be upgraded to no longer need a subpage. In place of static copied and pasted excerpts will be self-updating excerpts displayed through selective transclusion, using the template {{Transclude lead excerpt}}.

Maintainers of specific portals are encouraged to sign up as project members here, noting the portals they maintain, so that those portals are skipped by the maintenance pass. Currently, we are interested in upgrading neglected and abandoned portals. There will be opportunity for maintained portals to opt-in later, or the portal maintainers can handle upgrading (the portals they maintain) personally at any time.

### Background

On April 8th, 2018, an RfC ("Request for comment") proposal was made to eliminate all portals and the portal namespace. On April 17th, the Portals WikiProject was rebooted to handle the revitalization of the portal system. On May 12th, the RfC was closed with the result to keep portals, by a margin of about 2 to 1 in favor of keeping portals.

Since the reboot, the Portals WikiProject has been busy building tools and components to upgrade portals.

So far, 84 editors have joined.

If you would like to keep abreast of what is happening with portals, see the newsletter archive.

If you have any questions about what is happening with portals or the Portals WikiProject, please post them on the WikiProject's talk page.

Thank you. 07:28, 30 May 2018 (UTC)

## Can a PhD thesis be used as a source for a structure of an organic chemical?

Per title, that PhD thesis is a primary source but per that paragraph,

Completed dissertations or theses written as part of the requirements for a doctorate, and which are publicly available (most via interlibrary loan or from Proquest), can be used but care should be exercised, as they are often, in part, primary sources. Some of them will have gone through a process of academic peer reviewing, of varying levels of rigor, but some will not. If possible, use theses that have been cited in the literature; supervised by recognized specialists in the field; or reviewed by third parties. Dissertations in progress have not been vetted and are not regarded as published and are thus not reliable sources as a rule. Some theses are later published in the form of scholarly monographs or peer reviewed articles, and, if available, these are usually preferable to the original thesis as sources.

Shall I still use that thesis as a source? It is a good source because it shows explicitly the structure and its archaic (to this day) name on the same page. Outside of wikipedia, the PhD thesis is accessible electronically. --Ktsquare (talk) 07:03, 2 June 2018 (UTC)

You can use it if it is correct, especially if it is the first to reveal the structure. But see if you can confirm it is correct from a secondary, or reviewing source. Even if you can't find a better source, you can put in the primary source until someone else finds a superior one. However basing a whole article off one thesis is dubious, as notability is not proved by only having one source from one author. Graeme Bartlett (talk) 08:23, 2 June 2018 (UTC)
Some tertiary works or aggregator web sites can be used for structures eg for your use perhaps https://pubchem.ncbi.nlm.nih.gov/compound/225048 if your substance is 8-ethylcaffeine. Graeme Bartlett (talk) 08:28, 2 June 2018 (UTC)

## Naphthalene-1,5-dione

Could someone have a look at Draft:Naphthalene-1,5-dione? Is that the same compound as 1,5-dioxynaphthalene? Should it have its own article, or be merged somewhere else? – Uanfala (talk) 18:26, 2 June 2018 (UTC)

It looks to be the same substance. It's fair enough to decline AFC as there are no references. And where does all the property information come from in the chembox if it does not exist? Appears to be copied from ChemSpider predicted properties. Graeme Bartlett (talk) 23:13, 2 June 2018 (UTC)
Yep, I came to a similar conclusion, i.e. that the chembox was completed based on projections and guesses. ChemAbs search indicates that the parent is unknown and of mild interest. --Smokefoot (talk) 02:45, 3 June 2018 (UTC)

## Poly = 2 or >2?

I have never settled on the meaning of poly, as in polyamine. Is ethylenediamine a polyamine? My inclination is that it is not. --Smokefoot (talk) 21:06, 4 June 2018 (UTC)

I think =2 is out, the question is >1, or >2, or >N? The gold book says about polymers the structure of which essentially comprises the multiple repetition of units derived, actually or conceptually, from molecules of low relative molecular mass.[2] Multiple usually means >1. On the other hand, the convention should probably be whatever the sources say about the nomenclature. In condensed matter physics, a spin dimer is never called a polymer and dimerization is never called polymerization. --Mark viking (talk) 21:40, 4 June 2018 (UTC)
I just recheck an encyclopedia on organic amines: it has separate sections on diamines and polyamines, which seems to jive with what you say. --Smokefoot (talk) 21:56, 4 June 2018 (UTC)
Not referencing any source, but just thinking about my own use of poly_____, I would not call ethyldiamine a polyamine. I think poly is at least >2. Yilloslime (talk) 22:46, 4 June 2018 (UTC)
Unadulterated logic would indicate poly to mean ≥2. Anything else would just be an arbitrary delineation in the spectrum of variability. Adendum: consider oligomers. Plasmic Physics (talk) 09:24, 5 June 2018 (UTC)
polymer > olgiomer > dimer > monomer: A polymer is generally means much greater than two. Boghog (talk) 09:44, 5 June 2018 (UTC)
No, 'polymer' means 'more than one', nothing more. By tradition, it is taken to mean 'much more than one'. You're missing my point. Plasmic Physics (talk) 06:08, 7 June 2018 (UTC)
Most definitions of polymer contain the words "many" or "very high molecular weight". many > a few > one. Many is a large indefinite number that generally means much greater than two. Boghog (talk) 06:48, 7 June 2018 (UTC)
The original Greek poly- prefix means many. Graeme Bartlett (talk) 11:28, 7 June 2018 (UTC)
Yes, and 'many' and 'large' are subjective terms, but must by definition at least greater than one. Plasmic Physics (talk) 06:21, 8 June 2018 (UTC)
What if we shift our focus onto bulk properties? More precisely, if the substance in question has a singular structural formula, it is not a polymer; if the substance contain a gaussian mixture of formulae then it is a polymer. Compare tetracosane and polyethylene. Plasmic Physics (talk) 06:44, 8 June 2018 (UTC)

## Possible issue with <chem> markup at Propene#Combustion

Over at Propene#Combustion, there's this little equation:

${\displaystyle {\ce {\underbrace {2C3H6} _{propene}+\underbrace {9O2} _{oxygen}->\underbrace {6CO2} _{carbon\ dioxide}+\underbrace {6H2O} _{water}}}}$

I assume that the labels "propene", "oxygen", and "carbon dioxide" are meant to go under the bracket/underbrace, like they do for "water", rather than to the side of the molecules as they appear above. Anyone know how to fix this? I've been staring at the <chem> code for a while now and can't figure it out. I don't think is browser issue, as it appears the same way in various browsers and computers that I have tried. Yilloslime (talk) 19:52, 6 June 2018 (UTC)

I can't figure out why it appears that way either. But since I think the extra text is unnecessary and the equations simply look better in the same style/font as the rest of the text, I have replaced it. -- Ed (Edgar181) 20:30, 6 June 2018 (UTC)
The problem is coming from the last character which is a subscript in propene, oxygen and carbon dioxide, but not in the case of water. Snipre (talk) 22:29, 7 June 2018 (UTC)

## 4-Aminophenylmercuric acetate

Just made a stub for this compound. If someone were willing to add the "chembox" infobox to the article I'd be very appreciative. -Darouet (talk) 20:22, 7 June 2018 (UTC)

Done Graeme Bartlett (talk) 06:47, 8 June 2018 (UTC)

## Various Chemistry drafts

Over on WP:WPM we been working on identifying draft which come under our project and reviewing them at Wikipedia:WikiProject Mathematics/List of math draft pages. Part of this process involved finding draft which had mathematical of chemical equations in them. Quite a few of them come under your project and we have listed them at Wikipedia:List of draft pages on science and engineering. You may wish to examine these and see if any should be promoted to main space. --Salix alba (talk): 07:41, 12 June 2018 (UTC)

## Deletion discussion for Naphthalene-1,5-dione

Probably of interest to participants here: Wikipedia:Articles for deletion/Naphthalene-1,5-dione. XOR'easter (talk) 23:33, 12 June 2018 (UTC)

## Where to look for feasibility of a reaction

Hello there, while looking at the Cannizzaro reaction, can the aldehyde be replaced by an aldimine? Then the aldimine undergoes the reaction to yield an amine and an amide. Where can I look for information about that? At the moment, it seems original research. Secondly, on isobutyraldehyde, "it undergoes the Cannizaro reaction even though it has alpha hydrogen atom.", unsourced. On TishchenkoReaction, "the Tishchenko reaction is used to obtain isobutyl isobutyrate, a specialty solvent, sourced. So, does the isobutyraldehyde undergoes a Cannizzaro reaction to yield both the alcohol (isobutyl) and the carboxylate (isobutyrate)? Where can I look for information about that? Consequently, is or was there a collaboration on Organic Chemistry, say a Wikiproject? -- Mountainninja (talk) 01:50, 17 June 2018 (UTC)

## Migration away from old texvc [itex] engine

There is now a project to migrate away from the texvc renderer for [itex] expressions. This was the default a few years ago which produces PNG images, now we have a hybrid solution with uses MathJax in the backend to produce svg images and sometimes xml. There is still some legacy from texvc as it is used in the frist parsing step of the current engine. This means there are some idiosyncrasies in the syntax which differ from standard LaTex:

Current syntax Suggested replacement Comment
$\$ redefinition would involve changing the character code
% \% redefinition would involve changing the character code
\and \land causes normal align environment to fail
\or \lor see [3]; causes teubner to fail
\part \partial acceptable if the document doesn't use sectioning with \part.
\ang \angle this only conflicts with siunitx package.
\C \Complex conflicts with puenc.def e.g. from hyperref package
\H \mathbb{H} conflicts with text command \H{0} which is ő.
\bold \mathbf
\Bbb \mathbb
\pagecolor remove not needed and not working anymore, done on en-wiki mainspace
<ce>...</ce> <chem>...</chem> Chemistry environment, done on en-wiki mainspace

The first step in the project will involve deprecating the old syntax and running a bot or semi-automated edits to change the syntax. These should not result in any visible change to the pages. The bot doing the work is User:Texvc2LaTeXBot which is currently seeking approval. Changes will also be made to the Visual Editor to produce the new syntax.

Subsequent stages in the project are discussed at mw:Extension:Math/Roadmap, these involve some more complex problems with the <chem> syntax. Eventually the texvc part will be removed completely and there may be some slight change to the rendered output. The main discussion of the project happens at T195861 and your input is welcome. Discussion on the English wikipedia should be on WT:WPM--Salix alba (talk): 15:58, 22 June 2018 (UTC)

## Opinions sought

as to Draft:Amphetamine synthesis.Feel free to accept at your discretion, shall this be encyclopedic-ally notable enough :)WBGconverse 04:56, 27 June 2018 (UTC)

## Facto Post – Issue 13 – 29 May 2018

MediaWiki message delivery (talk) 18:19, 29 June 2018 (UTC)

## Any love for Chromatography?

The Fundamental resolution equation article is in need of love and is on the same equation as the Purnell equation article. I hate tedious algebra (talk) 04:03, 16 July 2018 (UTC)

## Acid strength definition

Buffer capacity for a 0.1 M aqueous solution of an acid with pKa of 7

Empirically, an acid can be said to be completely dissociated in solution when the concentration of molecules, HA, is below the detection limit for the species. There appear to be two, mutually incompatible, ways of quantifying what a strong acid is. See acid strength and acid dissociation constant for details.

1. An acid with a pK value less than -1.76.This applies only to aqueous solutions
2. An acid which is effectively 100% dissociated in solution

The first is the number -log10 55.5. 55.5 is the concentration/1M of H2O pure water. This seems to be the criterion commonly used for designating a compound as a superacid.

The second depends on the buffer capacity of the solvent, which rises very steeply with decreasing pH, starting at about pH 1 in aqueous solutions. This is independent of the pK value of the acid and is the cause of the solvent levelling effect.

For the purposes of this does strong acid = superacid? Superacid is defined by IUPAC "A medium having a high acidity, generally greater than that of 100 wt.% sulfuric acid" which our current sulfuric acid chembox would indicate as being anything below a pka of -3 (?). If strong acid is something else, my first question is: is there a formal definition? I've always thought it a loose term (in my head anything with a pka <1 is strong). If no universal definition exists it's not our job to create one.--Project Osprey (talk) 08:39, 20 July 2018 (UTC)
Hi you are right in that a superacid has an acidity greater than 100% sulphuric acid or less than -12 on the Hammett acidity function. At this level of acidicity pH isn't really used anymore. EvilxFish (talk) 13:46, 20 July 2018 (UTC)

## Facto Post – Issue 14 – 21 July 2018

MediaWiki message delivery (talk) 06:10, 21 July 2018 (UTC)

## Aromatic alcohol definition

I've found this problem checking Wikidata entries. I think you have an error in the definition of aromatic alcohol. The difference between aromatic alcohol and phenol is that in phenols hydroxy group is bonded directly to an aromatic ring (not neccesarily benzene ring) and in aromatic alcohols it is bonded indirectly (usually to the benzylic position). Right now definition in aromatic alcohol states that phenols = aromatic alcohols (however, Category:Aromatic alcohols says something different). Regards, Wostr (talk) 13:51, 21 July 2018 (UTC)

That is a substandard article that might be deleted. It is not supported by good references. It was created by a sockpuppet. I have no idea of the meaning of an "aromatic alcohol". Wikipedia has phenols, to which I propose to redirect aromatic alcohol, unless others disagree. BTW, phenols is in rough shape. It describes a large class of compounds.--Smokefoot (talk) 13:58, 21 July 2018 (UTC)
ChEBI defines "aromatic alcohol" as "Any alcohol in which the alcoholic hydroxy group is attached to a carbon which is itself bonded to an aromatic ring."[4] In my experience, this usage is not common ("benzylic alcohol" is clearer and less ambiguous vs phenol) and is also not the meaning used in our aromatic alcohol article (no requirement of the structural distance). The Manual of Scientific Style (I have no idea what standards-body is affiliated with this!) says "Aromatic alcohols (phenols) have the general formula Ar—OH."[5] and this usage seems to be present in the literature. But other sources clearly define phenols as being a disjoint set of hydroxyl functional group vs alcohols rather than a subset (IUPAC Gold Book specifically defines "alcohols" as OH attached to a saturated position). I think we are best with WP:TNT and writing a brief statement that the term is ambiguous, with pointers to the benzyl-alcohols and phenols articles. DMacks (talk) 20:46, 21 July 2018 (UTC)
Concur with TNT. --Smokefoot (talk) 23:33, 21 July 2018 (UTC)
Smokefoot redirected the title to phenols, which I think is the best thing to do for now. -- Ed (Edgar181) 13:24, 25 July 2018 (UTC)
No objection. I just did the same for Aromatic alcohols so that the plural and singular point to the same place. Would be interesting to scan WP for singular-vs-plural redirects that point to different targets, or where one is a redir to not-the-other. DMacks (talk) 13:42, 25 July 2018 (UTC)
@DMacks: That would be an interesting search. Maybe suggest it at Wikipedia talk:Database reports? -- Ed (Edgar181) 13:59, 25 July 2018 (UTC)
I posted at VPT (it also relates to a WP technical restriction). DMacks (talk) 14:10, 25 July 2018 (UTC)
Okay, thanks for solving this problem, but there is still Category:Aromatic alcohols. Wostr (talk) 20:26, 26 July 2018 (UTC)

## Nanodumbbell

I just started Nanodumbbell and have no idea what I'm doing. Please visit the article and see if the "Effect of Surfactant on Growth of ZnO Nanodumbbells..." external link is the right thing. Are these things silica or zinc or what? Many thanks! :) Anna Frodesiak (talk) 23:22, 24 July 2018 (UTC)

Usually one starts an article because we know our subject and we can demonstrate that the topic is notable. Notable usually means that the topic is featured in a book or a review article. But some good articles get started for strange reasons, and perhaps yours is an example of such. Probably however, if you have no idea what you are doing, the article is not worth writing.--Smokefoot (talk) 00:58, 25 July 2018 (UTC)
I agree it's kind of weird to start an article on a topic you don't know about :-) On the other hand, I've done a little searching and have convinced myself this is a reasonable topic for an article. Mostly I found research papers, but also some more general references, such as "Handbook of Less-Common Nanostructures". Google Books. Retrieved 2018-07-25. so I'm inclined to keep this and nurture it. -- RoySmith (talk) 13:49, 25 July 2018 (UTC)
It's the opposite axis as a molecular gyroscope. Rigid rotor is probably the parent article but that is already long and high-level/mathy, so this would not fit there (but should link back and forth) IMO. DMacks (talk) 14:30, 25 July 2018 (UTC)

## Covalent bond or not ?

Curating data in WD I often have a problem with metal oxides where some representations show them as ionic compound and others as covalent molecules. See for example zirconyl nitrate:

• Pubchem CID 11953300 with an ionic bond between oxygen and zirconium
• Pubchem CID 11506893 with a covalent bond between oxygen and zirconium

These different structures have a strong impact on structural identifiers like InChI, InChIKey or SMILES.

Similar problem for complex like sodium hexacyanoferrate:

• Chebi indicates covalent bonds between cyanide and iron giving OBOWFEZVRNRJBU-UHFFFAOYSA-N as InChIKey
• Pubchem indicates ionic bonds giving GTSHREYGKSITGK-UHFFFAOYSA-N as InChIKey.

Is there any good reference or rule to define which structure is the better in order to define only one possibility as structural identifier ? Snipre (talk) 15:45, 25 July 2018 (UTC)

"Don't trust PubChem structures" is my first rule for...well almost anything. But especially for things with metals or complex 3D forms. For example consider ferrocene:
DMacks (talk) 15:57, 25 July 2018 (UTC)
For your first case, anhydrous zirconyl nitrate (what your two CIDs illustrate) might not even exist whereas several hydrates do.[7] But the structure of the pure hydrate seems to be a bridged polymeric chain and at least some zirconium–nitrate structures have bidentate nitrates.doi:10.1007/s11172-005-0222-7 And what the heck even is CID 83761? DMacks (talk) 16:16, 25 July 2018 (UTC)
Pubchem seems to be maintained for bio-organic chemists, so it is not reasonable to rely on that database for structures of metal compounds. But within English Wikipedia, we are pretty careful with structures. If you see any structures that are suspect, please leave a note here! Zirconium is a tough one, as DMacks suggests. --Smokefoot (talk) 16:25, 25 July 2018 (UTC)
@DMacks and Smokefoot: Thanks for your comment, but can you give me a better reference database ? Or any other references ? Snipre (talk) 12:37, 27 July 2018 (UTC)

In some ways it may not matter as neither SMILES or InChI can correctly represent anything other than fully organic compounds. If you follow the rules correctly salts and organometallics become 'Disconnected' to give you free metal ions and organic ligands. You do sometimes see people create accurate looking structures by playing around manually, but you often find that these 'hacked' SMILES or InChI strings give different outputs on different software (octahedral bonding can be particularly troublesome). --Project Osprey (talk) 13:43, 27 July 2018 (UTC)

## Silicic acid

The AfD for Silicic acid was recently closed with a decision to keep, but the article itself could stand cleanup, I think. XOR'easter (talk) 15:33, 29 July 2018 (UTC)

OK, "silicic acid" was speedily deleted, which probably violates some policy or other about what to do with recently AfD'ed pages, but more importantly it makes the page history inaccessible. Silicic acid is now a redirect to silicon dioxide, and silicic acids is an article. XOR'easter (talk) 17:34, 1 August 2018 (UTC)
Could you check whether User:Galobtter managed to get everything back to the previous state? Silicic acid appears to be a full article with an extensive history (the only deleted revisions relate to page-moves and redirects) and Silicic acids is a redirect to it with no useful editorial history (nor anything in its deleted history). I could envision a good-faith discussion about whether the singular or plural should be the actual page-name for this apparent non-specific compound name. Is it in the realm of Wikipedia:Manual of Style/Chemistry/Compound classes or simply an ambiguous term? If it were to be plural, that doesn't automatically mean the singular should redirect to a different meaning (see WP:PRIMARY and WP:TWODABS). DMacks (talk) 18:07, 1 August 2018 (UTC)
Yeah I moved it back as it most likely shouldn't suddenly redirect to Silicon dioxide after 13 years of remaining an article, possibly breaking many of the links in and things like that (silicates may be a better target anyhow if one wanted to redirect it). Petergans - the information on the 2017 synthesis is good but probably should be integrated with the historical information in the previous version of Silicic acid.. Galobtter (pingó mió) 18:13, 1 August 2018 (UTC)
It looks like everything is in the right place — thank you very much! Whatever improvements need to be made now can probably happen through the day-to-day course of editing. XOR'easter (talk) 13:27, 2 August 2018 (UTC)

## Ethanol

I noticed late last night that an anon added the hazards template to ethanol here, but inadvertently seems to have referenced and copied data from a calcium hydroxide reference "NIOSH Pocket Guide to Chemical Hazards #0092". National Institute for Occupational Safety and Health (NIOSH). for the PEL limits. I tagged it not in citation. Would someone please correct this error? Jim1138 (talk) 17:37, 29 July 2018 (UTC)

## Often unsourced changes to NPAP 704 NFPA-H field

There are quite a few changes to teh NPAP 704 NPAP_h= field on the in ethanol, methanol (most common), and carbon dioxide articles. Sometimes deleting the source or referencing a photo. I often run across this while doing wp:RCP. What can be done to prevent this? Jim1138 (talk) 17:37, 29 July 2018 (UTC)

## oxidized fats

I noticed this redirect oxidized fats, which points to a specific cardiovascular disease article. I find that this makes little sense, since there should be many topics for this particular term. Do we have an article on the oxidation of fat? -- 65.94.42.168 (talk) 05:54, 31 July 2018 (UTC)

Rancidification? --Project Osprey (talk) 09:48, 31 July 2018 (UTC)
I've changed the target to that as being significantly better Galobtter (pingó mió) 18:15, 1 August 2018 (UTC)

## Help requested re chemical formula subscripts

At Talk:Chemical formula § Subscript ambiguity I've asked for help regarding the possible ambiguity of subscripts. —[AlanM1(talk)]— 23:20, 31 July 2018 (UTC)

## Nascent iodine

Someone might consider modifying the lede of Nascent iodine (dietary supplement) to indicate that the concept of nascency has been debunked. The problem is that the concept is so thoroughly debunked that if might be difficult to get a source. But for those naive readers wanting to read up on nascent iodine, we owe it to them to say that there is no such thing.--Smokefoot (talk) 02:11, 6 August 2018 (UTC)

Nascent state (chemistry) has some sources that look promising. Double sharp (talk) 02:16, 6 August 2018 (UTC)
Done and thank you. --Smokefoot (talk) 00:21, 7 August 2018 (UTC)

## Curaxins

Draft:Curaxins 2 is an Articles for Creation submission dealing with a family of anti-cancer molecules that needs attention from a subject matter expert. It would be great if someone could help out. Thanks! Catrìona (talk) 22:59, 6 August 2018 (UTC)

## Chembox

I've just finished a review of phosphoric acid. Once again, the clumsiness of the chembox is apparent. A large chembox like this one forces an editor to put pictures and tables on the left and generally leaves less space for the article text. What about mobile phone access?

Here is a suggestion: make all the categories collapsible, with "collapsed" as default setting, A chembox could look like this

 Phosphoric acid (title) Structures show Names show Identifiers show Properties show … …

It will then be easy for a user to show a single category and view its contents, rather than having to trawl through a long list to find what he/she is looking for. Petergans (talk) 15:52, 12 August 2018 (UTC)

Making the boxes collapsible is reasonable and could certainly be helpful for the extremely full chemboxes. But those situations are the minority, so if the sections become collapsible, then uncollapsed should be the default state. -- Ed (Edgar181) 18:08, 12 August 2018 (UTC)
I'm not a fan of auto-collapsed tables as a rule. If it is better for mobile access then at least go with default un-collapsed on browsers and default collapsed on mobile view. --Project Osprey (talk) 19:25, 12 August 2018 (UTC)