Why are metal oxides basic and non-metallic oxides acidic in nature?

Metal oxides are basic because they react with acids to form salt and water, while non-metallic oxides are acidic because they react with bases to form salt and water.

Metals usually lose electrons and form positive ions, so their oxides are ionic and basic in nature. Non-metals usually gain electrons, so their oxides are covalent and acidic.

Examples

• Metal oxides: Na₂O, CaO – react with HCl to form salt + water.
• Non-metallic oxides: CO₂, SO₂ – react with NaOH to form salt + water.

This difference is due to the chemical properties of metals and non-metals.