"Oxide" itself is the dianion of oxygen, an O2– (molecular) ion. Metal oxides thus typically contain an anion of oxygen in the oxidation state of −2.
Is oxide ion an anion?
This is the oxide anion. Because this species has no charge, it is an atom in its elemental form. This is cobalt. In this case, there is a 2+ charge on the atom, so it is a cation.
What charge is the oxide ion?
The oxide ion will have a charge of 2− as a result of gaining two electrons.
