The oxidation number of oxygen in superoxides is -1/2 i.e. O-1/2.
Oxidation number of an atom is defined as the charge that an atom appears to have on forming ionic bonds with other heteroatoms. An atom having higher electronegativity is given a negative oxidation state. The more electronegative atom acquire a negative charge while the less electronegative atom acquire a positive charge. Depending on this hypothesis oxygen have 5 oxidation states.
- Due to its high electronegativity, oxygen usually has a negative two charge.
- In all peroxides, oxygen has an oxidation state of −1.
- In all superoxides, oxygen has an oxidation state of − 1/2.