How are ionic metal oxides different from covalent nonmetal oxides?

Ionic metal oxides and covalent nonmetal oxides differ primarily in their bonding, structure, and chemical behavior when reacting with water.1

Bonding and Structure

• Ionic Metal Oxides: These compounds consist of metal cations and oxide anions ($O^{2-}$). They are typically crystalline solids formed by elements with low electronegativity (metals) bonding with oxygen.213
• Covalent Nonmetal Oxides: These compounds are generally molecular in character and feature covalent bonds between nonmetal atoms and oxygen. They form when elements with higher electronegativity share electrons with oxygen.14

Chemical Behavior

The most significant distinction lies in their acid-base character:

• Basic Nature: Ionic metal oxides are often called basic oxides because they react with water to form hydroxides, resulting in basic solutions. They also react with acids in neutralization reactions to produce salts and water.21
• Acidic Nature: Most nonmetal oxides are acidic. They react with water to form oxyacids, which yield hydronium ions in aqueous solution. They react with bases to form salts.51

As one moves across the periodic table from metals to nonmetals, there is a smooth transition in these properties from ionic and basic to covalent and acidic.1