How do ionic oxides differ from covalent oxides?

Ionic and covalent oxides differ primarily in their bonding nature, chemical composition, and reactivity with water.1

Bonding and Composition

• Ionic Oxides: These compounds consist of metal cations and oxide anions ($O^{2-}$). They are typically formed by alkali metals, alkaline earth metals, and transition metals in lower oxidation states.12
• Covalent Oxides: These compounds feature covalent metal-oxygen or nonmetal-oxygen bonds. They are generally molecular in character and are formed by nonmetals or transition metals in high oxidation states.12

Reactivity and Acid-Base Character

The chemical behavior of these oxides is often determined by their interaction with water:1
* Ionic Oxides: Often called basic oxides, they react with water to form hydroxides and produce basic solutions. They also react with acids to produce salts and water.12
* Covalent Oxides: Most nonmetal oxides react with water to form acidic solutions. Transition metal oxides with high oxidation states also exhibit acidic properties, reacting with hydroxide solutions to form salts.12

As one moves across the periodic table from metals to nonmetals, there is a smooth transition in bonding from ionic to covalent, accompanied by a shift from basic to acidic character.12