Carbon oxyanions

A carbonate is a salt of carbonic acid, (), characterized by the presence of the carbonate ion, a polyatomic ion with the formula CO32–. The word "carbonate" may also refer to a carbonate ester, an organic compound containing the carbonate group .

In inorganic chemistry, bicarbonate (American English: ) (IUPAC-recommended nomenclature: hydrogencarbonate) is an intermediate form in the deprotonation of carbonic acid. It is a polyatomic anion with the chemical formula HCO3–.

thumbnail|right|The general structure of dicarbonate esters