Wikipedia:Manual of Style/Chemistry

This document will aim to be brief, touching on the general aspects of chemistry-related articles. In-depth guides are found in the relevant sub-pages.

Other relevant pages:

• User:Itub/Ambiguous chemical identifiers

Scope

Since Wikipedia is an encyclopedia, not all articles are suitable for inclusion, WP:NOTABILITY being a general guide. Specific to Chemistry, articles which do merit inclusion include:

Compounds

• commercially available compounds, e.g. ...
• industrially significant compounds, e.g. hydrochloric acid (priority)
• compounds of historical, pedagogical, or academic interest, e.g. Zeise's salt, Dewar benzene, porphyrin

Reactions

• general reactions, e.g. alkylation, hydroamination
• reactions of industrial significance, e.g. Haber process, Monsanto process
• reactions of historical, pedagogical, or academic interest, e.g. ...

Obscure reactions should usually be mentioned in the general class of reaction itself. Sub-classes of general reactions should be split off when appropriate, e.g. nucleophilic aromatic substitution.

Analytical techniques

• analytical techniques commonly used, e.g. elemental analysis, NMR spectroscopy
• analytical techniques of historical, pedagogical, or academic interest, e.g. flame test, classical inorganic analysis, sodium fusion test

Obscure analytical techniques should be included only if it meets notability guidelines

Laboratory/industrial apparatus and equipment

• common equipment should be described; niche equipment such as fleakers and Glindemann rings should be discussed in an appropriate section

Chemists

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General

Nomenclature

Main article: /Nomenclature

Per WP:ENGVAR, the type of English used to write the articles does not matter, but it should be consistent. There are a few exceptions for chemical names:

• "sulfur" (and related "sulfuric", etc)., "caesium", and "aluminium" should be spelled this way regardless of the English variation used in the article, being the IUPAC names for these elements
• "phosphine" is preferred over "phosphane", being predominantly used in the chemical literature

Systematic nomenclature, while being precise, can be very cumbersome. Where commonly accepted trivial or alternative names exist, they should be used over systematic names. In particular, IUPAC recommends ^[1] 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

Structure drawing

Main article: /Structure drawing

Appropriate formats are PNG and SVG. ACS settings have been adopted as the convention. Images should be legible at either 250 pixel width (half page width in article) or 600 pixel width (full page width in article). Images that can be reduced to 250 pixel width (or lower) are preferred, as this simplifies the page formatting.

Indexes used for numbering must be superscript: R¹-CH₂-R² (not R₁-CH₂-R₂). Hydrogens should be implied (hidden), except for the benefit of the target audience. The use of Me to denote methyl may be confusing. The use of Et, Pr, etc., is discouraged. When Ph is used to denote phenyl and X for halogen or any atom, it should be clearly defined within the image.

Article types

Compounds

Main article: /Chemicals

All articles on chemicals, real or hypothetical, should have a Chembox. Formula should be readily available, variables like n, x, or y are permissible for substances of variable composition such as polymers. For compounds of defined composition, the molar masses should be available as well. The article should cover these aspects as appropriate:

• Introductory paragraph (WP:lede)
• Properties
• Occurrence
• Preparation
• Uses and/or reactions
• History
• Safety
• Toxicology
• Suppliers should not be listed unless the compound is rare and only available from one or two suppliers
• References

Compound classes

Main article: /compound classes

These articles belong to one of these categories:

• functional groups (alcohols, aldehydes, acids, nitriles)
• "backbone" moieties, both organic and inorganic
  • steroids, aldohexoses, terpenes
  • metal oxo compounds, metal carbonyl compounds, metal clusters
• ions (nitrates, perchlorates, triflates, tetrafluroborates

Articles discussing compound classes should be clearly distinguished from the compound for which the class is named. An example is quinoline versus quinoline (compound class).

Aspects to be covered include:

• Nomenclature
• Structure and bonding
• Properties
• Characterization
• Applications
• Occurrence
• Preparation
• Reactions
• History
• Safety

Reactions

Main article: /Reactions

Simple reactions can be typed out in text. Reactions should be indented with a colon ":". For example:

2 Na + 2 H₂O → 2 NaOH + H₂

Avoid the use of <math> notation: the existing character set is adequate to enter reaction data; the change in size and font from is very jarring to the reader. Ionic equations are preferred. State symbols are omitted unless it is relevant (e.g. thermochemistry, to illustrate precipitation for chemical separation). "Heat" should not be a reaction product; stating ΔH_r, or giving its sign is preferable:

C₂H₅OH(g) + 3 O₂(g) → 2 CO₂(g) + 3 H₂O(l) (ΔHr = −1409 kJ/mol)

Instead of:

C₂H₅OH(g) + 3 O₂(g) → 2 CO₂(g) + 3 H₂O(l) + heat

Compounds and/or atoms should not be wikilinked in the reaction. These links should be in the surrounding text.

Non-trivial reactions should be drawn as images.

Laboratory/industrial apparatus and equipment

A description of the function and the design of the piece. References tend to come in the form of product brochures and catalogs. Niche items should be mentioned in the next larger set.

Analytical techniques

Principles behind these techniques should be used. For example, atomic absorption spectroscopy should describe spectral lines; NMR spectroscopy should describe the spin of nuclei. Simple calculations may be used to illustrate certain concepts; detailed calculations should be omitted.

Chemists

• Nobel prize winners
• People who have a reaction named after them
• etc. etc.

See notability for people