Wikipedia:Naming conventions (chemistry)
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This page documents an English Wikipedia naming convention. It is a generally accepted standard that editors should follow, though it should be treated with common sense and the occasional exception. When editing this page, please ensure that your revision reflects consensus. When in doubt, discuss first on the talk page. |
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[edit] General rule
From Wikipedia:Naming conventions:
- "Generally, article naming should give priority to what the majority of English speakers would most easily recognize, with a reasonable minimum of ambiguity, while at the same time making linking to those articles easy and second nature."
[edit] IUPAC preferred name vs. systematic name
IUPAC recommends the use of non-systematic names for some organic compounds, and these recommendations should be followed in article titles. Examples:
| Acetic acid | not | Ethanoic acid |
| Toluene | not | Methylbenzene |
| Lysine | not | 2,6-Diaminohexanoic acid |
[edit] Element names
Traditionally, the names of three elements have been spelled differently in US and British English. For article about chemical substances, Wikipedia follows the recommendations of the International Union of Pure and Applied Chemistry (IUPAC) as follows:
| Aluminium | not | Aluminum |
| Sulfur | not | Sulphur |
| Caesium | not | Cesium |
These international standard spellings should be used in all chemistry-related articles on English Wikipedia, even if they conflict with the other national spelling varieties used in the article.
[edit] Use of Stock nomenclature
Stock nomenclature for inorganic compounds is based on the indication of the oxidation number (as a roman numeral, in parentheses) of each of the major elements in the compound, e.g. iron(III) chloride. It is widely, if sometimes incorrectly, used on Wikipedia for the titles of articles about inorganic compounds. It is not obligatory, as there are other acceptable methods for naming these compounds, but it is often preferred as the most common non-ambiguous name for a substance. The following guidelines are based on current WikiBestPractice:
- Only the cationic element (i.e. the element whose name appears unchanged in the compound name) is assigned its oxidation number. Except in rare cases (none at present), we do not assign the oxidation number in the anion: hence potassium permanganate not potassium manganate(VII), sodium hypochlorite not sodium chlorate(I).
- There is no space between the end of the element name and the opening parenthesis: hence silver(I) fluoride not silver (I) fluoride. Note that this is an exception to the usual English style for parentheses.
- It is not necessary to specify the oxidation number when there is no possibility of ambiguity in the compound title: hence sodium chloride not sodium(I) chloride.
- Stock nomenclature should only be used for ionic compounds. Compounds with a substantial degree of covalency should be named by stoichiometric nomenclature: hence titanium tetrachloride not titanium(IV) chloride.
- Stock nomenclature should not be used for compounds with mixed or non-integral oxidation numbers: hence triiron tetraoxide not iron(II,III) oxide (in fact, this article is difficult to name and, as an exception, redirects to magnetite).
[edit] Drug-related articles
Where a compound has a WHO International Nonproprietary Name (INN), this should be used as the article title.
[edit] Prefixes
For technical reasons, it is not recommended to use non-numerical prefixes in article titles. This includes:
| Positional identifiers | ortho-, meta-, para-, α-, β-, γ- |
| Stereochemical identifiers | cis-, trans-, (E)-, (Z)- |
| Chiral identifiers | (R)-, (S)-, D-, L-, (+)-, (−)- |
Note that iso in such compounds as isopropanol is not only permitted but recommended. No hyphen is used in these cases. sec- and tert- are hyphenated and non-capitalized, and should be avoided if possible on Wikipedia.
When the chosen article title starts with a number, the first letter of the compound name should be capitalized: hence 1,1,1-Trichloroethane not 1,1,1-trichloroethane. A redirect from the uncapitalized version should be created to simplify linking from other articles. See also Capitalization below.
[edit] Redirects
- From Wikipedia:Deletion policy: "Don't worry, redirects are cheap."
Redirects should be created for:
- Alternative names for the compound, including acronyms where appropriate;
- Alternative capitalizations, where there is a numerical prefix in the article title.
[edit] Exceptions
Even with the best will in the world, no set of guidelines can cover every case. Some articles on Wikipedia have non-standard titles through consensus that this is the most commonly used name (in scientific circumstances) for the compound concerned, whatever IUPAC or the other rules suggest. For example:
- Ethylene oxide not oxirane
- Phosphine not phosphane (and for substituted phosphines, arsine and stibine)
- Wilkinson's catalyst not chlorotris(triphenylphosphane)rhodium
- Vaska's complex not carbonylchlorobis(triphenylphosphane)iridium
Please do not get into revert wars over the naming of an article: the best place for discussion is on the article's talk page or (failing that) at Wikipedia talk:WikiProject Chemicals.
[edit] Capitalization of elements and compounds
The names of chemical compounds and chemical elements when written out, are common nouns in English. They are capitalized at the beginning of a sentence or title, but not elsewhere. Note that for chemical elements this applies to the word only and not the chemical symbol, which is always capitalized. Both rules remain even with chemical elements derived from proper names which would otherwise be capitalized, in keeping with IUPAC policy to differentiate proper names from things named after proper names. Thus, it is californium but the symbol is Cf, and einsteinium, but symbol Es. Note that names for odd or rare chemicals are uncapitalized like common ones, and thus uranium and plutonium (symbols U and Pu) should be uncapitalized like carbon or iron (symbols C and Fe). This rule (full name uncapitalized but symbol capitalized) applies also to isotopes and nuclides, when completely written out: thus 14C but carbon-14. IUPAC Provisional Recommendations for the Nomenclature of Inorganic Chemistry (2004). (The element mercury is uncapitalized, but of course the planet and god Mercury remain capitalized proper nouns).
Prefixes such as sec-, tert, ortho-, meta-, para- and the numerical prefixes are not considered part of the name: the first letter of main part of the name should still be capitalized where appropriate. The exception is iso-, which is part of the name and therefore not italicized or hyphenated. Substituent groups do form part of the name: hence the correct article title is 2-Aminoethanol, which is written as 2-aminoethanol if not at the start of a sentence. Note that the two wikilinks refer to separate articles: one is a redirect to the other.
[edit] See also
- List of organic compounds
- List of inorganic compounds
- Wikipedia:WikiProject Chemicals
- Wikipedia:WikiProject Chemicals/Style guidelines
[edit] References
- ^ Panico, R.; & Powell, W. H. (Eds.) (1994). A Guide to IUPAC Nomenclature of Organic Compounds 1993. Oxford: Blackwell Science. ISBN 0-6320-3488-2.
- ^ International Union of Pure and Applied Chemistry (2005). Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005). Cambridge (UK): RSC–IUPAC. ISBN 0-85404-438-8.pp. 47, 248. Electronic version.
