Cobalt(II) oxide is represented by the molecular formula CoO. It may also be called cobalt monoxide. Cobalt(II) oxide can be formed from the decomposition of cobalt(III) oxide.
The molecular formula for cobalt(II) oxide shows that it includes one atom of cobalt and one atom of oxygen. The Roman numeral II in the parenthesis after the Co symbol indicates the charge of the cobalt. For example, cobalt(II) has a charge of positive two, while cobalt(III) has a charge of positive three. As a solid, cobalt(II) oxide appears either as a crystal or a powder. It is used in ceramics to make the color cobalt blue. Cobalt(II) oxide has a molar mass of 74.93 grams per mole.