How do peroxides differ from superoxides?

Peroxides and superoxides are distinguished primarily by the composition of their oxygen ions and the resulting oxidation states of the oxygen atoms.

• Peroxides: These compounds contain the peroxide ion, ${\text{O}}_2^{2-}$, in which each oxygen atom is assigned an oxidation state of $-1$. A prominent example is hydrogen peroxide (${\text{H}}_2{\text{O}}_2$), a major industrial chemical used as a bleach, disinfectant, and antiseptic. Metallic peroxides, such as barium peroxide (${\text{BaO}}_2$), also feature this ion.12
• Superoxides: These compounds contain the superoxide ion, ${\text{O}}_2^{-}$, where the oxygen has an oxidation number of ${-}^1{/}_2$. The stability of these compounds is linked to the size and electropositive character of the associated metal; larger, more electropositive metals (such as potassium, rubidium, and cesium) form more stable superoxides. These are typically yellow to orange paramagnetic solids that act as strong oxidizing agents and react vigorously with water to produce oxygen gas.34

Both classes of compounds function as strong oxidizing agents, but they differ fundamentally in their ionic structure and electronic configuration.321