Physics A2 Radioactivity


Nuclear and Thermal Physics Specification

Topics within Specification

  • Evidence for the nucleus
  • Alpha, Beta and Gamma radiation
  • Radioactive Decay
  • Nuclear Instability
  • Nuclear Radius
  • Mass and Energy
  • Induced Fission
  • Safety Aspects
  • Thermal Energy
  • Ideal Gases
  • Molecular Kinetic theory model
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Discovery of the Nucleus

  • 1899- Ernest Rutherford discrimated between three types of ionising radiation: alpha, bet and gamma
  • in 1909 researchers used alpha particles to fire at gold atoms
  • when a beam of positively charged alpha particles is fired at a thin gold film, most will pass through but some are deflected as they pass near to the nucleus
  • some particles are deflected by more than 90° so they bounce back
  • this evidence means that inside the atoms there must be small positively charged nuclei, which repel the passing alpha particles
  • the nucleus must be small since very few alpha particles are deflected by much
  • it must be positive to repel the positively charged alpha particles
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