History of the Atom

Describe how the evidence collected from firing alpha particles at thin gold foil caused the plum pudding model of the atom to be replaced by the nuclear model.

[4 marks]

Visual Mark Scheme Breakdown

• What is the Plum Pudding model? (1 mark)

  • sphere with a weak positive charge

  • electrons embedded

  (1 mark)

• What was predicted for the Gold Foil Experiment? (1 mark)

  • They predicted positive alpha particles would pass through the weak positive charge

    (1 mark)

• What actually happened in the Gold Foil Experiment? (1 mark)

  • Many went through

  So lots of empty space

  • Some were deflected

  • Some came back

  So concentrated mass & positive charge in the centre

  (1 mark)

• What model was developed as a result? (1 mark)

  Nuclear Model:

  • Mainly empty space

  • Concentrated mass and positive charge in Nucleus

  (1 mark)