Template:Did you know nominations/Oxohalide

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The following discussion is an archived discussion of the DYK nomination of the article below. Please do not modify this page. Subsequent comments should be made on the appropriate discussion page (such as this nomination's talk page, the article's talk page or Wikipedia talk:Did you know), unless there is consensus to re-open the discussion at this page. No further edits should be made to this page.

The result was: promoted by Miyagawa (talk) 09:19, 25 January 2012 (UTC)


Created/expanded by Petergans (talk) at 10:39, 28 December 2011 (UTC)

  • Pictogram voting keep.svg Length of article, date of creation and sources are fine. The hook reference is offline so is accepted in good faith. The hook is very technical however. Might it not be better to use something a bit easier to understand? Cwmhiraeth (talk) 07:42, 3 January 2012 (UTC)
  • I think its cute that it spells "Mom" (original hook). Crisco 1492 (talk) 08:01, 3 January 2012 (UTC)

I agree, the alternative hook will be better for the general reader. From a scientific point of view, the linear M-O-M structure is very unusual, so this will catch the interest of the more specialized reader. It's a familiar quandary, how to balance the general and the specialized. I'm equally happy with the alternative hook and the original. Petergans (talk) 08:36, 3 January 2012 (UTC)

Symbol question.svg Um... The article is nicely referenced, except for the part at the beginning that contains the basic definition and description of oxohalides, including the hook fact. Can inline citations be added for the hook fact and in the first half of "Synthesis and properties" (presumably citing one of the standard reference/text books listed under "Bibliography")? --Orlady (talk) 22:06, 3 January 2012 (UTC)

There was already an inline reference in the sentence, in the article body, containing the hook fact (reference now no. 18). I have added details of the original publication. Also added a reference to the sentence on synthesis. Petergans (talk) 10:27, 4 January 2012 (UTC)

Symbol possible vote.svg I am glad to see the additional citations. However, I fear that we may be talking past each other. When I said the hook fact needed a source, I was not referring to the original hook about the M-O-M structure. That hook fact is sourced, but an alternate hook was suggested because that hook is not nearly "hooky" enough (too dauntingly technical for DYK). I was thinking of the more simple-minded hook about "chemical compounds in which both oxygen and halogen atoms are attached to another chemical element". Regardless of whether that hook is used is at DYK, the fundamental point of the article is the definition of the oxyhalide group is, and that definition needs to be supported by one or more citations to published sources. Similarly, the statement "There are 3 general methods of synthesis" should be supported by a citation to a source that identifies these as three general methods; the statement that details of synthesis of individual compounds can be found in cited books "in sections relating to the specific element" does not suffice for this purpose. (It's not sufficient to cite sources for the esoteric details; the fundamentals also need to be sourced.) Additionally, the article still has some full paragraphs that are completely unsourced, such as the paragraph about oxohalide compounds of the actinides.
The ALT hook that Cwmhiraeth suggested is not as dauntingly technical as the original, but it's not especially interesting. I'm wondering about the possibilities of a hook along the lines of ".... that the oxohalide compounds of elements in high oxidation states are intensely coloured?" or "...that the highly toxic chemical phosgene is an example of an oxohalide and is a useful reagent for the formation of carbonyl compounds?" --Orlady (talk) 05:55, 9 January 2012 (UTC)
Whatever. My personal druthers would be to use a hook that does not scare away casual users, but that has enough substance to draw the attention of users who have enough knowledge and interest in the subject matter that they might possibly be able to improve the article. Regardless, the DYK rules require adequate sourcing in the article, which means (among other things) that the main concepts presented in the article need to be supported by citations. --Orlady (talk) 14:31, 9 January 2012 (UTC)

1) Much of this is distressingly familiar - seeking citations for stuff that has been known for donkeys years. It's all factual, all of it can be found in many chemistry text-books. 2) Also, there appears to be a misunderstanding as to who might be interested in this article. I put it to you all that nobody who has not studied chemistry to some extent will be interested in a chemistry article. 3) The insistence on citations in each paragraph negates the idea that WP is an interactive medium. For uranyl I would have though that reference to the article that has 16 citations would be enough. It would be silly to repeat all 16 citations in this article. 4) I really don't care what you people decide is the best hook. I just want the article to be noticed. Petergans (talk) 15:56, 11 January 2012 (UTC)

Verifiability of content is of paramount importance at Wikipedia. --Orlady (talk) 20:08, 11 January 2012 (UTC)
I understand that. However it does not mean, in my view, that every fact has to be separately verifiable in all the articles in which it appears.
I find this kind of nit-picking a complete waste of time. Everything in this article is verifiable in the books listed in the bibliography or in the citations.Petergans (talk) 12:43, 12 January 2012 (UTC)
  • If so, then citing it should be a breeze. Crisco 1492 (talk) 16:21, 12 January 2012 (UTC)

I have responded to the original issues. I rest my case. Petergans (talk) 20:39, 14 January 2012 (UTC)

  • Symbol delete vote.svg Referencing still under par, nominator does not seem willing to address the issue. Statements such as "they give useful information on relative bond strengths. For example, in CrO2F2, the Cr–O stretching vibrations are at 1006 cm−1 and 1016 cm−1 and the Cr–F stretching vibrations are at 727 cm−1 and 789 cm−1. The difference is much too large to be due to the different masses of O and F atoms. Rather, it shows that the Cr–O bond is much stronger than the Cr–F bond. M–O bonds are generally considered to be double bonds and this is backed up by measurements of M–O bond lengths. It implies that the elements A and O are chemically bound together by a σ bond and a π bond." come across as original research if not cited. Crisco 1492 (talk) 06:10, 15 January 2012 (UTC)

These facts are covered by "assigned in detail" (reference 5), which precedes this sentence. Petergans (talk) 11:14, 15 January 2012 (UTC)

Done. Petergans (talk) 12:42, 15 January 2012 (UTC)

Symbol possible vote.svg It's still not working for me. The description of "oxohalide" given in the lead still is not sourced in the lead -- and it appears nowhere else in the article.
I've looked for a source for the basic definition/description, but without much success. (Sunday is not a good time to access libraries.) However, I found a reasonable basic definition online on this book page, but the definition is somewhat different from what's in this article. (In particular, it defines oxyhalides as anions, not as the compounds they form -- presumably because the source deals with oxyhalides in aqueous solution.)
The reason you can't find it is that it's an ancient term with a commonly accepted meaning. So much so, that sections in text books are commonly entitled "halides and oxohalides"as you Google book page shows. Oxo- is the IUPAC recommended notation: oxy- is an older usage. I don't cite the IUPAC reference because it is concerned only with nomenclature. The definition is virtually a tautology as the name itself clearly means a compound containing oxygen and halide.Petergans (talk) 20:03, 15 January 2012 (UTC)
Actually, I found a lot more online content about oxyhalides than about oxohalides. In spite of the conclusions you've drawn about my qualifications, I do know how to search both spellings. And, as it happens, Wikipedia generally calls for sources in articles that define/describe "ancient terms with commonly accepted meanings," particularly when they are technical terms. --Orlady (talk) 04:56, 16 January 2012 (UTC)
Additionally, as noted above, the "source" cited for the statement "There are 3 general methods of synthesis" is not a valid source. Not only does it fail to name a source for the identification of the three "general methods", but saying "Synthesis of individual compounds can be found in Housecroft&Sharpe and Greenwood&Earnshaw in sections relating to the specific element" is essentially telling the reader "If you want to know something about this subject, read the cited sources." That does not meet Wikipedia's policy goal of verifiability based on reference citations to reliable sources. Subsequent to the passage about the three "general methods," there is a long multi-paragraph passage that is largely unsourced:
In addition, various oxohalides can be made by halogen exchange reactions and this reaction can also lead to the formation of mixed oxohalides such as POFCl2 and CrO2FCl.

You appear not to understand the nature of the statement "three general methods.." It is a summary of facts scattered throught the sources. I have not been able to find a source dealing with oxohalides as a group. Instead they are usually discussed in the context of the of individual elements.Petergans (talk) 20:03, 15 January 2012 (UTC)

If this is a generalization you wrote, based on your own summary/synthesis of published sources, it would be considered WP:Original research. --Orlady (talk) 04:56, 16 January 2012 (UTC)
In relation to the oxide or halide, for a given oxidation state of an element A, if two halogen atoms replace one oxygen atom, or vice versa, the overall charge on the molecule is unchanged and the coordination number of the central atom decreases by one. this is a factPetergans (talk) 20:03, 15 January 2012 (UTC)
Factual information needs to be substantiated by citations to reliable sources. --Orlady (talk) 04:56, 16 January 2012 (UTC)
For example, both phosphorus oxychloride, POCl3 and phosphorus pentachloride, PCl5 are neutral covalent compounds of phosphorus in the +5 oxidation state. If an oxygen atom is simply replaced by a halogen atom the charge increases by +1, but the coordination number is unchanged. This is also a statement of factPetergans (talk) 20:03, 15 January 2012 (UTC) This is illustrated by the reaction of a mixture of a chromate or dichromate salt and potassium chloride with concentrated sulfuric acid.
[Cr2O7]2− + 4Cl + 6H+ → 2CrO2Cl2 + 3H2O
The chromyl chloride produced has no electrical charge and is a volatile covalent molecule which can be distilled out of the reaction mixture.<ref>Sisler, H. H. "Chromyl Chloride" Inorganic Synthesis McGraw-Hill: New York, 1946; Vol. 2, pp. 205–207.</ref>
I note that the reference cited at the end of that passage deals only with the synthesis of chromyl chloride, which makes it unlikely that it deals with the general topic of the effect of halogen-oxygen replacement on coordination number and charge, nor the examples of phosphorus oxychloride and phosphorus pentachloride. Also, readers likely will be put off by the fact that the reaction described as including potassium chloride and sulfuric acid does not include either species (instead, it shows only the H+ from the sulfuric acid and the chloride ion from the KCl).
That's because the other ions are not involved in the chemical reaction.Petergans (talk) 20:03, 15 January 2012 (UTC)
True, but since the text describes the reaction in terms of compounds, the compounds should be included in the reaction. --Orlady (talk) 04:56, 16 January 2012 (UTC)
There appear to be a few other issues of missing citations later in the article, too. An article can't be included in DYK on the main page when it shows so little regard for WP:V. --Orlady (talk) 17:09, 15 January 2012 (UTC)
It appears that none of the contributors to this discussion, apart from User:Cwmhiraeth, has any knowledge pertinent to the subject matter of this article. With regret, my last word is : do as you think fit. Petergans (talk) 20:03, 15 January 2012 (UTC)
Sigh... --Orlady (talk) 04:56, 16 January 2012 (UTC)
Petergans posted some followup on my talk page, and I responded there: User talk:Orlady#Oxohalide. I hope he will follow through with the relatively modest changes that the article seems to need. --Orlady (talk) 20:07, 16 January 2012 (UTC)
The discussion on my talk page has become rather long, so I am copying it here for "the record":

I take exception to your statement "when it shows so little regard for WP:V." 23 references - little regard?. Please look at my user page and you'll see how many articles that I have written have been accepted for DYK.

On the question of defining the term oxohalide, it appears (pardon me if I'm wrong) that you know no chemistry. The names of chemical compounds are governed by IUPAC Chemical nomenclature rules. In this case oxo means "contains an oxygen atom" and halide means "contains a halogen atom (hal) in a negative oxidation state (ide)". Therefore the name itself is a definition of a class of compounds.

So cite IUPAC. The citations for the lead sentence of Oxocarbon are a fine example. --Orlady (talk) 19:07, 16 January 2012 (UTC)

Your suggestion that the equation

[Cr2O7]2− + 4Cl + 6H+ → 2CrO2Cl2 + 3H2O

should contain chemical compounds is wrong because any chloride salt (NaCl, KCl..) or dichromate salt (Na2Cr2O7, K2Cr2O7) would do equally well. Sulphuric acid is not included as such because it is in vast excess. The equation expresses the stoichiometry of the reaction, so it is right not to include things that do not take part in the chemical reaction. I can see that the layman might be confused by this, but such confusion can occur with any technical subject matter.

So in place of "This is illustrated by the reaction of a mixture of a chromate or dichromate salt and potassium chloride with concentrated sulfuric acid," why not write "This is illustrated by the reaction of a mixture of a chromate or dichromate salt and a chloride salt with a strong acid"? --Orlady (talk) 19:07, 16 January 2012 (UTC)

a)The original sentence reflected the cited source. The reaction is fun to demonstrate to students, so the recipe is relevant. b) It has to be concentrated sulphuric acid (normally 98%) because otherwise the product would be destroyed (hydrolyzed) by water in the acid. It seemed right in the context not to include this detail. Another detail that I left out is that the reaction cab been used as the basis for a test for the presence of chloride in a mixture. There's only so much detail that one can include.

It's your article, not mine. If it's important that the reaction include concentrated sulfuric acid and KCl, then show the whole reaction. --Orlady (talk) 21:49, 21 January 2012 (UTC)

Incidentally, in common parlance "strong acid" means concentrated, corrosive etc. but in chemistry it means another thing , namely fully dissociated. Another instance illustrating the difficulty of conveying technical material to the layman. Petergans (talk) 10:42, 17 January 2012 (UTC)

I am aware that "strong acid" is not the same thing as "concentrated acid," and I believe that it is appropriate to call H2SO4 a strong acid. And I don't know who advised you that calling a person an ignoramus is a good way of winning a debate, but that wasn't good advice. --Orlady (talk) 21:49, 21 January 2012 (UTC)

The following is copied from my talk page. --Orlady (talk) 15:41, 22 January 2012 (UTC)

Yes, sulphuric acid is a "strong acid", but not in this context. The dissociation reaction

H2SO4 + H2O ⇌ HSO4 + H3O+

is essentially complete in dilute aqueous solution, so the term "strong" is applicable in that context. In 98% sulphuric acid, however, there is not enough water to allow this reaction to go to completion. Details of the dissociation reactions in concentrated sulphuric acid are in Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 0-08-037941-9.  and they are quite different from the reactions in aqueous solution.

I certainly did not mean to imply that you are an ignoramus, and apologise if I gave that impression. It seemed to me, as one with 40+ years experiance of teaching chemistry, that you were out of your depth on the technicalities of this subject matter, and the paragraph above illustrates this to me. The fundamental problem is that in chemistry we use a specialized language which can be misunderstood by the non-specialist. In WP this is an issue because of the wide range of readership.

It's an old story, raised back in the 1959 by C.P. Snow in The Two Cultures. It becomes a significant problem in WP when, as in this case, a non-specialist "reviews" specialist material. We had a huge row of this nature when we tried (and failed) to get acid dissociation constant accepted as a today's featured article.

The scientific literature is structured in a different way to other literatures. There are primary publications for research results, secondary publications which review research papers and tertiary publications like text books which are mostly based on review articles and previous text-books. Stuff that gets into text books is common knowledge as it appears in many of them. We've (i.e. not just me) had this discussion about common knowledge over and over again as it appears to conflict with the WP requirement for verification. There's a lengthy discussion of this in relation to chemistry somewhere in WP, but I've forgotten where it is.

Perhaps in the light of these observations you might withdraw your objection in DYK? Petergans (talk) 10:57, 22 January 2012 (UTC)

I found the article Wikipedia:Scientific citation guidelines I couldn't remember. I believe that its guideleines have been followed. Petergans (talk) 12:41, 22 January 2012 (UTC)

Quote from Wikipedia:Scientific citation guidelines#Uncontroversial knowledge

The verifiability criteria require that such statements be sourced so that in principle anyone can verify them. However, in many articles it is cumbersome to provide an in-line reference for every statement. In addition, such dense referencing can obscure the logical interdependence of statements. Therefore, in sections or articles that present well-known and uncontroversial information – information that is readily available in most common and obvious books on the subject – it is acceptable to give an inline citation for one or two authoritative sources (and possibly a more accessible source, if one is available) in such a way as to indicate that these sources can be checked to verify statements for which no other in-line citation is provided. These inline citations are often inserted either after the first sentence of a paragraph or after the last sentence of the paragraph; a single convention should be chosen for each article.

I believe the current text satisfies these criteria.Petergans (talk) 19:46, 22 January 2012 (UTC)

Symbol confirmed.svg This article satisfies all DYK criteria. Unreferenced statements are basic chemical facts that fall under "You don't need to cite that the sky is blue" policy. --İnfoCan (talk) 15:18, 24 January 2012 (UTC)
I would suggest the following ALT6 hook: "... that unlike other oxygen compounds, some oxohalide ions contain a linear M—O—M structure (where M = W, Ru, Os)?
--İnfoCan (talk) 15:30, 24 January 2012 (UTC)

Along these lines, How about alt 7 hook Some oxohalide ions contain the very unusual linear M–O–M structure (M = W, Ru, Os)? Petergans (talk) 16:57, 24 January 2012 (UTC)