Talk:Dictionary of chemical formulas

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[edit] Rules used on this page

The formulae in the list have been ordered according to these rules:

  1. Element A comes before element B, and B before C, &c.
  2. Element A comes before element Ai where i is a natural number.
  3. Element A2 comes after element A1, and A3 after A2, &c.
  4. Element Ax comes after element A.
  5. Element Ay comes after element Ax.
  6. Element Ayj comes after element Axi no matter what the natural numbers i and j happen to be.
  7. A comes before AB.
  8. AB comes before AC, and AC before AD, &c.
  9. A comes before A−; A− comes before AB.
  10. If element X comes before element Y, then compound AX comes before compound AY.
  11. Parentheses should be ignored unless two compounds with parentheses are the same except for the subscript of the parentheses: ABC comes before A(BC)2, and A(BC)2 comes before A(BC)3, &c.
  12. Brackets (for coordination complexes) should be treated similarly to parentheses: ignore unless there is a tie.
  13. The compound must have at least two atoms, otherwise it is an element or an ion, but not a compound. (The "dictionary" being a list of compounds.)
  14. Hyphens (for single bonds) are ignored unless there is a tie. Likewise for equals signs (for double bonds) and equivalence signs (for triple bonds).
  15. Structural formulae can only be included if they are linear (one-dimensional) alphanumeric strings all of whose atoms are explicitly labeled, e.g.: hexane may be included as C6H14, CH3CH2CH2CH2CH2CH3, CH3-CH2-CH2-CH2-CH2-CH3, or CH3(CH2)4CH3 but not as ASCII art in which six C atoms and 14 H atoms are arranged like six black pieces and 14 white pieces on a go board. Structural formulae which are two-dimensional or three-dimensional cannot be included, e.g.: structure of rhombic sulfur, aniline, tetraphosphorus decaoxide, α-D-glucose, β-lactose, ATP, cyclopentanoperhydrophenanthrene skeleton, protoporphyrin IX, myoglobin diagram. No Haworth projections, no Fischer projections, no quasi-linear diagrams which look like sentence diagrams. A formula is includeable iff it is a string whose characters are any of the following: (1) letters, in upper or lower case, or in italics; (2) numbers, subscripted, superscripted, or otherwise; (3) plus and minus signs, esp. superscripted; (4) parentheses; (5) brackets; (6) hyphens, equals signs, and equivalence signs; (7) asterisks (or interpuncts), spaces, and periods. (Note: minus signs might be used instead of hyphens for single bonds, since minus signs are slightly longer.)
  16. Dotted compounds (for complex ions) are first placed by ignoring the dot (interpunct or asterisk) and whatever comes after it, but if there is a tie with a neighboring compound then the compound after the dot will be considered. In particular, A * B comes after A. If C comes after B then A * C comes after A * B.
  17. If A comes before B then A * C comes before B.
  18. The same compound may be included more than once if it has more than one includeable formula.
  19. Different names for the same formula may be included, in which case they are separated by line breaks (<br>).
  20. A formula may refer to different structural isomers. In this case, the names of the different isomers should each be placed on a separate subrow in the table in alphabetical order, as shown below.
  21. If several isomers have a collective name, it should be given in parentheses below the chemical formula. Each distinct collection of isomers should be placed within a separate major row, with the formula repeated as necessary.
Benzenediol isomers
C6H6O2
(benzenediols)		 catechol 120-80-9
hydroquinone 123-31-9
resorcinol 108-46-3

Anyone who wants to is invited to edit the dictionary, adding new compound formulas, removing formulas, adding alternative names for a given formula, adding hyperlinks from the name of a compound to its article, &c. just as long as the rules (or at least the most important ones, such as the first ten) are followed.

[edit] Questions

  • Should hyphens, equals signs, and equivalence signs be included, or should they be removed from a formula before the formula is included in the list?
Regarding whether or not to include -, = etc in formulae, you need to consider what your naive student of chemistry is likely to find in their book. If the book uses both forms, then ideally you should have both. However, there are many cases (even simple ones like benzene) where you simply can't write the formula with text any other way than the molecular formula, C6H6. So I would suggest that you have a policy of initially just trying to write formulae without hyphens etc, then just add a few of the simpler formulae like butane later if you feel the need (this is what I think you did anyway!). Walkerma 03:45, 14 July 2005 (UTC)
En-dashes look better than hyphens for single bonds. Physchim62 11:15, 14 July 2005 (UTC)
I think, for consistency, it would be better to not include these. ‣ᓛᖁ♀ᑐ 11:23, 13 September 2005 (UTC)
  • Should ions be included?
I suspect that it's not necessary to include hydrates, as this would just add a lot of extra work for little gain. If they are included, the normal Wikipedia format uses · for hydrates. For complexes, that format is rather obsolete (at least 50 years old?), the usual way these days uses square brackets, as you have used. If by complex you mean things like Lewis acid/base adducts (e.g. BF3·OEt2) then I think the middot is the way to go. Walkerma 03:45, 14 July 2005 (UTC)
I agree; hydrates do not seem to add much. ‣ᓛᖁ♀ᑐ 11:23, 13 September 2005 (UTC)
  • Would interpuncts be preferable to asterisks for denoting complex ligations?
Middots should be used for hydrates, [square] brackets for complexes (except the simple P-block cases mentioned by Martin). Physchim62 11:15, 14 July 2005 (UTC)
  • Would it be appropriate to include organic shorthands such as Me, Et, and Ph?
The use of Me as an abbreviation of methyl is not to be encouraged (it causes problems for German speakers), other abbreviations should be listed at the appropriate place in the order of empirical formulae. Physchim62 11:15, 14 July 2005 (UTC)
  • If a compound can be described by more than one chemical formula, which should be included?
From looking at the organic compounds, the tables may get very unwieldy if parenthesized formulas are included. In my opinion, it would be better to avoid these as much as possible. ‣ᓛᖁ♀ᑐ 21:08, 13 September 2005 (UTC)
  • This page is very long, and likely to become longer. Would the dictionary be better organized with a subpage for each letter?

[edit] Page to delete

Is this page in use anymore? Dictionary_of_chemical_formulas/F? If not it should be deleted. -Ravedave 06:36, 27 January 2006 (UTC)

Oh and so should: Dictionary_of_chemical_formulas/Merge/C30-C39 - Ravedave 06:37, 27 January 2006 (UTC)
The pages that have become redirects due to page moves could be deleted, I suppose, though there isn't a pressing need to. Note that Dictionary of chemical formulas/F and some other letters are transcluded by Dictionary of chemical formulas. The merging of Dictionary of chemical formulas/Merge is also not finished. ‣ᓛᖁ♀ᑐ 06:54, 27 January 2006 (UTC)
User:Danaman5 created a category and I applied it to F since it wasn't on it. Good enough for me. -Ravedave 00:04, 8 February 2006 (UTC)

[edit] Categorization

There were many uncategorized articles associated with this dictionary, so I created the new category "dictionary of chemical formulas" and placed everything associated with this dictionary into it. Feel free to change this system or suggest a better one, but for now I just felt that the articles needed to be categorized somewhere. Danaman5 23:53, 7 February 2006 (UTC)

[edit] Naming System

Would it be beneficial to also include IUPAC name of the compound into the table as well? MathStuf 21:25, 11 April 2006 (UTC)

[edit] Double Up

Is there a reason why other list's exist in conjuction with this one, specifically List of CAS numbers by chemical compound. Aren't they essentially the same thing? Wouldn't it make more sense to arrange that page by CAS number? --Russoc4 23:39, 26 September 2006 (UTC)

Yes, those are awfully similar! And yes, the name of that other page implies that the list is sorted by CAS number. I would talk to User:Thricecube about this, he created the "List of CAS numbers" page, see if he is planning on reorganizing it. Walkerma 02:13, 27 September 2006 (UTC)
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