Chemical Properties of Metals and Non-metals

Chemical Properties of Metals and Non-metals

Reaction of Metals with Oxygen:

When metals react with oxygen, they form metal oxide.

Metal + O₂ → Metal Oxide

For Example:

1. Copper + Oxygen → Copper Oxide (black)

2Cu + O₂ → 2CuO

2. Aluminium + Oxygen → Aluminium Oxide

4Al + 3O₂ → 2Al₂O₃

3. Magnesium + Oxygen → Magnesium Oxide

2Mg + O₂ → 2MgO

The reactivity of metals with oxygen differs. For Example:

• Sodium and Potassium react so vigorously with air that they catch fire when they are kept in open. Hence, they are immersed in kerosene to store them.
• The surfaces of Magnesium, Aluminium, Zinc and Lead are covered with a thin layer of oxide to make sure that they do not get oxidized anymore.
• While iron does not burn when heated, iron filings burn vigorously.
• The copper surface is coated with a thin layer of black copper oxide to prevent the process of further oxidation from taking place.
• Gold and silver do not react with Oxygen.

Amphoteric Oxides: Some metal oxides react both with acids and bases to produce salts and water. Such metal oxides are called amphoteric oxides. For example:

Aluminum Oxide + Hydrochloric Acid → Aluminium Chloride + Water

Al₂O₃ + 6HCl → 2AlCl₃ + H₂O

Aluminum Oxide + Sodium Hydroxide → Sodium Aluminate + Water

Al₂O₃ + 2NaOH → 2NaAlO₂ + H₂O

Reaction of Metals with Water

Metal + (cold) Water → Metal hydroxide + Hydrogen

Metal + Stream → Metal oxide + Hydrogen

For Example:

Sodium + Water → Sodium Hydroxide + Hydrogen + Heat

2Na + 2H₂O → 2NaOH + H₂ + Heat

Calcium + Water → Calcium Hydroxide + Hydrogen

Ca + 2H₂O → Ca(OH)₂ + H₂

Magnesium + Water → Magnesium Hydroxide + Hydrogen

Mg + 2H₂O → Mg(OH)₂ + H₂

Aluminium + Water → Aluminium Oxide + Hydrogen

2Al + 3H₂O → Al₂O₃ + 3H₂

Iron + Water → Iron Oxide + Hydrogen

3Fe + 4H₂O → Fe₃O₄ + H₂

The reactivity of metals with water differs. For Example:

• Sodium, Potassium and Calcium react with cold water.
• Magnesium reacts slowly with hot water to form slightly soluble magnesium hydroxide.
• Aluminum, Zinc and Iron react with steam.

• Lead, Copper, Silver and Gold do not react with water.

Note: Calcium and magnesium float on water as bubbles of hydrogen stick to their surface.

The reaction of Metals with Solutions of Other Metal Salts

Metal A + Salt Solution of Metal B → Salt Solution of Metal A + Metal B

More reactive metals replace less reactive metals.

Less reactive metals cannot replace more reactive metals.

For Example:

Iron + Copper Sulphate → Iron Sulphate + Copper

Fe + CuSO₄ → FeSO₄ + Cu

The reactivity series is given below:

The reaction of Different Metals and Non-metals with Acids

Note:

• When metals react with acids, they produce hydrogen gas with produces a 'pop' sound when it burns.
• Iron reacts with hydrochloric acid and sulphuric acid on heating.
• Copper does not react with hydrochloric acid (even when it is heated) but reacts with sulphuric acid on heating.