C1 - Development of the model of the atom

• Describe Niels Bohr's Nuclear Model

  Electrons orbit at very specific distances from the nucleus, in shells or energy levels.
• Who discovered the Neutron?

  James Chadwick
• Describe the Plum Pudding Model

  An atom is ball of positive charge, with negative electrons embedded in it
• Describe the Alpha-Scattering experiment

  Scientists fired alpha particles at a thin piece of gold foil in a vacuum.
• What were the results of the Alpha-Scattering experiment?

  What did the Scientists conclude from these results?

  Most alpha particles passed straight through the gold foil

  Meaning that most of an atom is empty space

  Some of the alpha particles were deflected by a large angle

  Meaning that the centre of the atom has a positive charge

  Very few alpha particles were deflected

  Meaning that the mass of an atom is concentrated at its centre
• What did John Dalton believe?

  • Matter was made up of tiny spheres
  • Atoms couldn't be broken up
  • Different elements were made up of different types of atoms
• Which model is this? Who made it?

  • Plum pudding model
  • JJ Thomson

  
• What are the differences between the Nuclear model of the atom and the plum pudding model of the atom?

  1. Nuclear model: mass is concentrated in the nucleus Plum pudding model: mass is evenly distributed
  2. Nuclear model: positive charge is in the nucleus
  3. Plum pudding model: ball of positive charge
  4. Nuclear model: mostly empty space
  5. Plum pudding model: has no empty space