The term persulfate (sometimes known as peroxysulfate) refers to ions or compounds containing the anions SO2−
5 or S
2O2−
8. The anion SO2−
5 contains one peroxide group per sulfur center, whereas in S
2O2−
8, the peroxide group bridges the sulfur atoms. In both cases, sulfur adopts the normal tetrahedral geometry typical for the S(VI) oxidation state. These salts are strong oxidizers.