Anion

A cation is a positively charged ion, with more protons than electrons, while an anion is negatively charged, with more electrons than protons.

A displacement reaction is a chemical reaction in which the cation or anion of one reactant is replaced by one from another reactant.

An oxyanion is an anion that contains the element oxygen.

In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid.