2.1.7 Discuss the uses of radioisotopes.

Source:  2.1.7 Discuss the uses of radioisotopes.    Tag:  radioisotope tracers
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 

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