Chapter 6Nuclear Energy

6.1 Radioactive Substance

Radioactive substances has unstable nuclei, and

will eventually break up/decay by emitting particles or radiation spontaneously.

Radioactive substance are known as radioisotopes

Examples: radium-226, carbon-14, cobalt-60 and iodine-131

Types of Radioactive Radiation

When the nuclei of a spontaneously, three types of radioactive radiation is emitted;

i) Alpha(α)-Positive charge

ii) Beta(β)-Negative charge

iii) Gamma(γ)-Neutral

radioactive decay

Penetrating Power of the Radiation

Production of Nuclear Energy

Fission of Uranium-235 produce two new nucleus and releases nuclear energy. This process is called fission of radioactive substance

The Uses of Radioactive Substances Agriculture

1.Gamma rays are used to - sterilise pests- Produce new breeds of quality plants

2.Radioisotopes are used as-detectors to study the absorption and use of

phosphate by plants. Ex: phosphorus-32

3.Carbon-14 is used to study the path of carbon in the photosynthesis of green plants

Medicine

1.Gamma rays-from cobalt-60 are

used to kill cancer cells (radiotherapy)

-are used to sterilise instruments used in an operation

2.Radioisotopes are used

-as tracer in internal organs

-to trace the growth of tumour in the brain.

Ex: iodine-131 is used to detect any damage to the thyroid gland

Archaeolgy:Carbon Dating

Radioisotopes carbon-14 is used to study the age of ancient artifacts.

Industry

1.Controlling the thickness of materials

ex: thickness of paper,plastic,aluminium

2.Detecting the leakage of underground pipes.

-Geiger-Muller counter is used to trace the radiation

Food Preservation

Gamma Rays

-used to sterilise food (kill bacteria,fungi or insects)

-prevent potatoes and vegetables from germinating (storage purpose)

Exercise 1

1.Give the meaning of radioactive substances.

2.Give two examples of radioactive substances and two of radioisotopes.

3.State one use of radioactive substances in each of the following field

i) Medicineii) Industryiii) Agriculture