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  • Created by: Stephers
  • Created on: 28-04-14 16:28
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  • Radioactivity
    • Alpha Scattering Experiment
      • Hans Geiger and Ernest Rutherford
      • Alpha particles are aimed at a thin gold foil. A fluorescent screen surrounds the experiment so that if an alpha particle is struck the screen a tiny flash of light was produced and can be viewed with a microscope
      • Or The Geiger-Marsden experiment
      • Most of the alpha particles pass through the foil
        • Most of the atoms of the gold foil are empty space
      • A small fraction of the particles were back scattered
        • A small dense + charge exists in the centre of the atom which holds most of the atoms mass -the nucleus. And the electrons orbit the nucleus
    • Alpha
      • Same as helium
      • +2
      • Paper can stop alpha particles
      • Deflected by a magnetic field
    • Plum Pudding Model
      • J.J. Thompson
      • The atom is composed of electrons surrounded by a soup of positive charge (pudding) to balance the electrons' negative charge (plums)
      • The Rutherford-Bohr model then proves the plum pudding model wrong a few years later
    • Background Radiation
      • Radiation that is present when sources have been removed
      • Eg. In our bodies/in our food i.e. bananas
      • Measured in becquerel (bq)
        • 1bq = 1 decay per minute
    • Beta
      • Fast moving electron
      • -1
      • Aluminium stops beta particles
      • Deflected by magnetic field - greater than alpha because of smaller mass
    • Gamma
      • 0
      • High energy electromagnetic wave
      • Lead can stop gamma rays
      • Not deflected by a magnetic field as has no charge
    • Radioactivity
      • The nuclei of some atoms are unstable
        • These nuclei will decay and give out forms of radiation - radioactive atoms
      • Decay is random and spontaneous
      • We can't influence or predict when individual nuclei will decay


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