JSS 3: RADIOACTIVITY

Radioactivity is the spontaneous emission of radiation from the nucleus of an atom.

               Radioactive elements

Examples of radioactive elements include:

1. Uranium (U)

2. Radium (Ra)

3. Thorium (Th)

4. Polonium (Po)

5. Actinium (Ac) etc

                 Types of radiation 

There are three main types of radiations emitted during radioactive decay:

I. Alpha (α) rays

II. Beta (β) rays

III. Gamma (γ) gamma

            Properties of Alpha Rays (α)

1. Alpha rays are positively charged particles made up of two protons and two neutrons (same as a helium nucleus, ⁴₂He).

2. Each alpha particle carries a +2 charge.

3. They are heavy compared to beta particles and gamma rays.

4. They travel at a low speed (about one-tenth the speed of light).

5. They have very high ionizing power

6. They have low penetrating power. They can be stopped by a sheet of paper, skin, or a few centimetres of air.

7. Effect on Magnetic/Electric Field:

They are deflected towards the negative plate in an electric or magnetic field because of their positive charge.

              Properties of Beta Rays (β) 

1. Beta rays are streams of fast-moving electrons

2. They are negatively charged (-1).

3. They are very light particles, with a mass almost 1/1836 that of a proton

4. They travel at a very high speed, close to the speed of light.

5. They have moderate ionizing power that is less than alpha particles but greater than gamma rays.

6. They have medium penetrating power — can pass through paper but are stopped by a thin sheet of aluminium

7. They are deflected by electric and magnetic fields.

         Properties of Gamma rays (γ)

1. Gamma rays are electromagnetic waves with very short wavelengths and high energy.

2. Gamma rays have no charge (they are neutral).

3. They have no mass.

4. They travel at the speed of light (about 3 × 10⁸ m/s).

5. They have low ionizing power compared to alpha and beta rays.

6. They have very high penetrating power. They can pass through paper, aluminium, and even several centimetres of lead or concrete.

7. They are not deflected by electric or magnetic fields.

               Radiations in electric field

                 

                 Uses of radioactivity 

1. It is used in Medicine for:

I. Treating cancer (radiation therapy).

II. Sterilizing surgical instruments.

III. Tracing and diagnosing diseases.

2. It is used in the Agriculture for:

I. Preserving food by killing bacteria.

II. Improving crop yield.

3. It is used in Industry for:

I. Detecting leaks in pipes.

II. Controlling the thickness of materials.

4. It is used in nuclear reactors to generate electricity.

          Dangers of radioactivity 

I. It causes cancer, burns, and genetic damage.

II. It can contaminate the environment and make food and water unsafe.

III. Prolonged exposure is dangerous to health.

                   Safety measures 

I. Avoid direct contact with radioactive materials.

II. Store radioactive substances in lead containers.

III. Use protective clothing and gloves.

IV. Limit exposure time.

V. Follow strict safety regulations in laboratories and hospitals.

                          Assignment

1. Identify the letters:A,B,C,D and E in the diagram above

2. Give three (3) examples of B

3. State the function of A

4. Give two (2) properties each of C, D & E