4.2.1 Radioactive Decay & Nuclear Radiation

• What is radioactive decay?

  The process of the nucleus of an atom giving out radiation attempting to make itself less unstable.
• What is activity?

  The rate at which a source of unstable nuclei decays.
• What is activity measured in?

  Becquerel (Bq).
• What is count-rate?

  The number of decays recorded each second by a detector.
• What is an example of a decay detector?

  Geiger-Muller tube.
• What are the three types of radiation?

  Alpha, beta, and gamma.
• Which type of radiation is the most ionising?

  Alpha radiation.
• What is an alpha particle made up of?

  Two protons and two neutrons.
• What is a beta particle made up of?

  One electron.
• What is a gamma ray made up of?

  Electromagnetic radiation from the nucleus.
• What is an alpha particle the same as?

  A helium nucleus.
• What is the charge of an alpha particle?

  +2.
• What is the charge of a beta particle?

  -1.
• What is the charge of a gamma ray?

  0.
• What causes the emission of a neutron?

  A nucleus has too many neutrons making it unstable.
• What can an alpha particle not penetrate through?

  Paper/skin.
• What can a beta particle not penetrate through?

  Thin aluminium.
• What can a gamma ray not penetrate through?

  Very thick lead.
• What is a beta particle the same as?

  An electron.
• What is the source of a beta particle?

  A neutron decaying into a proton and an electron.
• Which type of radiation is weakly ionising?

  Gamma.