The thin layer of oxide acts as a protective layer, preventing further oxidation of the metal at ordinary temperatures.

Metals like potassium and sodium react vigorously with oxygen and can catch fire if exposed to air. Keeping them immersed in kerosene oil prevents accidental fires and protects them from reacting with atmospheric oxygen.

Carbon exists in different forms called allotropes. Diamond, the hardest natural substance with a high melting and boiling point, and graphite, a conductor of electricity, are two allotropes of carbon.

Iodine, despite being a non-metal, exhibits luster, which is a characteristic property of metals.

Electric wires are coated to insulate and protect against electric shock. Metals that produce a sound on striking a hard surface are termed sonorous.