C1.2

Cards (3)

  • John Dalton
    • atoms cannot be broken down into anything smaller
    • the atoms of a given element are identical to each over
    • the atoms different elements are different from one another
    • during chemical reactions atoms rearrange to make different substances
  • J.J Thompson
    • Plum pudding model
    • atoms are spheres of positive charge
    • electrons are dotted inside
  • The Geiger-Marsden experiment 
    • Hans Geiger and Ernest Marsden tested the plum pudding model. They aimed beams of positively-charged particles at very thin gold foil. These particles should have passed straight through, according to the plum pudding model. However, many of them changed direction. Ernest Rutherford explained these results in his ‘planetary model’:
    • atoms have a central, positively charged nucleus with most of the mass
    • electrons orbit the nucleus, like planets around a star