radioactivity

• Radioactive decay

  The process where some isotopes have an unstable nucleus and give up radiation to become stable
• Types of nuclear radiation

  • Alpha particle
  • Beta particle
  • Gamma ray
  • Neutron
• Alpha particle

  Consists of two protons and two neutrons, the same as the nucleus of a helium atom
• Beta particle

  An electron ejected from the nucleus at high speed, formed when a neutron changes into a proton and an electron
• Gamma ray

  A type of electromagnetic radiation from the nucleus, not a particle
• Neutron

  A type of radiation sometimes given up by an unstable nucleus
• Radioactive decay is a completely random process, scientists cannot predict when a nucleus will decay
• Activity

  The rate at which unstable nuclei decay, measured in Becquerels (Bq)

  1 Becquerel = 1 decay per second
• Count rate

  The number of decays recorded each second by a detector like a Geiger-Muller tube, not the same as activity due to background radiation