Superoxides are the species having an O−O bond and O in an oxidation state of −
1
2
(superoxide ion is O2−). Usually these are formed by active metals such as KO2,RbO2 and CsO2. For the salts of larger anions (like O2−), lattice energy increases in a group. Since, lattice energy is the driving force for the formation of an ionic compound and its stability, the stability of the superoxides from ' K ' to 'Cs' also increases.