In general, polar solutes dissolve in polar solvents, and nonpolar solutes dissolve in nonpolar solvents. Ionic compounds (see above) typically dissolve only in polar solvents.
Molecular compounds are also either ''organic'' or ''inorganic''. [[Organic compound
|Organic compounds]] contain carbon; inorganic compounds do not. Polyatomic ions may also be organic or inorganic -- though an organic polyatomic ion is usually a dissociated weak organic acid of the form R-COOH, where R is the rest, or ''residue'', of the molecule.
== Descriptors of Compounds ==
: <small>''Main Article: [[Chemical formula]]''</small>
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.
==== Simple formula ====
=== Formula Mass ===
The ''formula mass'' of any compound (ionic or molecular) is equal to the sum of the [[atomic mass
|atomic masses]] of its constituent elements. If the compound is molecular, then the terms ''molecular mass'' or ''molar mass'' may properly describe this quantity.