Chemistry – Metals - Properties of metals | e-Consult

Metals react with oxygen to form metal oxides. The type of oxide formed depends on the metal's reactivity and the conditions of the reaction. The reaction can be spontaneous or require heating.

• Highly Reactive Metals (e.g., Sodium, Potassium): React vigorously with oxygen to form oxides. Sodium forms sodium oxide (Na₂O), and potassium forms potassium peroxide (K₂O₂).
• Moderately Reactive Metals (e.g., Magnesium, Aluminium): React with oxygen to form metal oxides. Magnesium forms magnesium oxide (MgO), and aluminium forms aluminium oxide (Al₂O₃).
• Less Reactive Metals (e.g., Iron, Copper): React with oxygen to form metal oxides, but the reaction is often slow and requires heating. Iron forms iron(III) oxide (Fe₂O₃), and copper forms copper(II) oxide (CuO).

The oxides formed can be basic or acidic, depending on the metal. For example, sodium oxide (Na₂O) is a strong base, while aluminium oxide (Al₂O₃) is amphoteric (can react with both acids and bases). The formation of a protective oxide layer on the surface of some metals (e.g., aluminium, chromium) prevents further reaction with oxygen.