/* Chemical Formula */ format
== Descriptors of Compounds ==
=== Chemical Formula ===
: ''Main Article: [[Chemical formula]]''
The ''chemical formula'' of any compound (ionic or molecular) is either a list of the [[Chemical symbol|chemical symbols]] of its constituent elements, with subscripts to describe their ratio, or else a slightly more complex listing or even a drawing intended to describe not merely the ratio of the constituent elements but also their arrangement. A chemical compound might have as many as three types of formulas.
==== SMILES ====
: Main Article: [[Simplified molecular input line entry specification|SMILES]]
The '''simplified molecular input line entry specification''' is a one-line specification of a structural formula that does not require any special data types or drawings. For details, see the linked main article. The SMILES for [[carbon dioxide]] is O=C=O, and that for acetic acid is CC(=O)O. The SMILES for sodium chloride is <nowiki>[Na+].[Cl-]</nowiki>, a form that emphasizes the character of this compound as a crystal or other pairing of disconnected ions.