JSS 1: RADICALS

                          Radicals 

A radical is a group of atoms that acts as a single unit and carries either a positive or negative charge during a chemical reaction.

Radicals behave as units and take part in the formation of chemical compounds.

For example:

• SO₄²⁻ — Sulphate radical
• NO₃⁻ — Nitrate radical
• OH⁻ — Hydroxide radical
• NH₄⁺ — Ammonium radical

              Types of Radicals

The two types of radicals are:

I. Positive radicals

II. Negative radicals 

                Positive Radicals

These are radicals that carry a positive charge.

Examples:

		Negative Radicals

These are radicals that carry a negative charge.

Examples:

Characteristics of Radicals

1. A radical consists of two or more atoms in most common cases.
2. The atoms in a radical act as a single unit.
3. Radicals carry a positive or negative charge.
4. They combine with oppositely charged ions to form electrically neutral compounds.
5. The charge on a radical is important when writing the formula of a compound.

Examples of Compounds Containing Radicals

Example 1: Sodium hydroxide

Sodium ion = Na⁺
Hydroxide radical = OH⁻

Therefore:

Na⁺ + OH⁻ → NaOH

Example 2: Calcium sulphate

Calcium ion = Ca²⁺
Sulphate radical = SO₄²⁻

Therefore:

CaSO₄

Example 3: Aluminium sulphate

Aluminium ion = Al³⁺
Sulphate radical = SO₄²⁻

To balance the charges:

Al₂(SO₄)₃

The bracket shows that the SO₄ group acts as one unit, occurring three times.

Class Activity

Identify the radicals in the following compounds:

1. NaOH
2. KNO₃
3. CaCO₃
4. Na₂SO₄
5. (NH₄)₂SO₄

Answers

1. OH⁻ — Hydroxide
2. NO₃⁻ — Nitrate
3. CO₃²⁻ — Carbonate
4. SO₄²⁻ — Sulphate
5. NH₄⁺ — Ammonium and SO₄²⁻ — Sulphate

Assignment 

1. What is a radical?
2. State the two types of radicals.
3. Give two examples of positive radicals.
4. Give four examples of negative radicals.
5. What is the charge on the sulphate radical?
6. Identify the radical in CaCO₃.
7. Write the formula of aluminium sulphate.