Nomenclature of inorganic sulfur compounds

Peroxyacids and their salts
Peroxyacids have a peroxo group -O-O- instead of -O- oxygen in the molecule.

Polyacids and their salts
Polyacids are theoretically formed by removing water from two molecules of a simple oxoacid (which is why they used to be called ``pyro'' acids).

Thioacids and their salts
Thioacids are theoretically formed by replacing oxygen -O- in oxyacid with sulfur -S-:
 * H2SO4 sulfuric acid – H2S2O3 thiosulfuric acid.

Dithionic acid, thionic acids and their salts
These compounds contain a chain of several covalently linked sulfur atoms.

Hydrogen sulfide and sulfides
From hydrogen sulfide H2S is derived the oxygen-free hydrogen sulfide with the same formula. Its salts are sulphides. Sulfur can also form polysulfides, e.g. FeS2 iron disulfide (pyrite).