2.1.7 Discuss the uses of radioisotopes.

The stability of a nucleus depends on the balance between the number of protons and neutrons. When a nucleus contains too may or too few neutrons, it is radioactive and becomes stable by giving out radiation.

Alpha Particles - emitted by nuclei with too many protons to be stable, (are helium atoms).

Beta Particles - emitted by nuclei with too many neutrons, (are fast moving electrons).

Gamma rays - form of electromagnetic radiation, (are waves).

Radioactive isotopes can be used for;

• preserve food
• detect cracks in structural materials 
• generate energy in nuclear power stations 
• sterilize surgical  instruments in hospitals 

USES OF ISOTOPES 

Carbon-14 used for dating materials

• unstable isotope of Carbon-12
• present in living plants
• continually replenished from carbon present in carbon dioxide in the air  
• when organisms die, no more carbon-14 is absorbed and the levels of carbon-14 fall because of nuclear decay
• this process occur at a regular rate, it can be used to date carbon containing materials
• rate of decay is measured by its half life

Cobalt-60 used in radiotherapy

• treatment of cancer and other diseases with ionization radiation
• treatment damages genetic material inside a cell by knocking off electrons and making it impossible for the cell to grow 
• normal cells are able to recover if treatment is carefully controlled
• cobalt-60 emits very penetrating gamma radiation

Iodine-131 as a medical tracer

• radioisotopes have the same chemical properties as their stable atom, but their positions can be monitored by detecting radiation levels, making them suitable for medical tracers
• emits both beta particles and gamma rays 
• short half life (of 8 days), so can be eliminated from the body quickly

Examples of iodine isotopes 

• compound sodium iodide to investigate the activity of thyroid gland and to diagnose and treat thyroid cancer
• iodine-125 used in treatment of prostrate cancer. Pellets of the isotope are implanted into the gland. (Half life of 80 days).

Dangers 

• living organisms can be affected if they are exposed to uncontrolled radiation, (excessive treatment).