Radioactive decay

• Alpha particles


  Helium nuclei
• Alpha radiation


  Alpha particle (α) emitted from the nucleus
• Alpha particles

  • Two neutrons and two protons (like a helium nucleus)
  • Don't penetrate very far into materials and are stopped quickly - They can only travel a few cm in air and are absorbed by a sheet of paper
  • Strongly ionising due to their size
• Beta particles


  High-speed electrons released by the nucleus
• Beta particles

  • Have no mass and 1 charge
  • Moderately ionising
  • Penetrate moderately far into materials before colliding and have a range of a few metres
  • Absorbed by a sheet of aluminium (around 5mm)
• For every beta particle emitted

  A neutron in the nucleus has turned into a proton
• Alpha decay involves the emission of an alpha particle, which consists of two protons and two neutrons.
• Beta decay occurs when a neutron in the nucleus transforms into a proton, emitting a beta particle (electron) or a positron.
• The half-life is the time it takes for one-half of the radioactive nuclei to undergo decay.
• Radiometric dating involves comparing the ratio of parent and daughter nuclides to calculate how much time has passed since they were formed.
• Radioactivity can be detected by measuring the ionization produced when alpha, beta or gamma particles pass through air.
• Radioactivity can be used as a tool to determine the age of rocks, fossils, or other materials by measuring the amount of parent and daughter nuclides present.
• Alpha radiation has low penetrating power and high ionizing ability.
• Gamma rays have high penetrating power but low ionizing ability compared to alpha and beta particles.
• Nuclear fission is the splitting of heavy nuclei into smaller fragments with the release of energy.
• Nuclear fission is the process whereby a heavy nucleus splits into smaller fragments, releasing energy and producing new elements.
• Energy released during nuclear processes comes from the mass defect between the sum of masses of individual nucleons and the total mass of the nucleus.
• Nuclear fission is the process whereby a heavy nucleus splits into smaller fragments, releasing large amounts of energy.
• Gamma radiation is produced during nuclear reactions and decays as high energy photons that do not interact with matter until they encounter another atom.
• Geiger counters are used to detect radiation levels.