History of the Atom

Dalton’s Model

1. The atom was a solid sphere that did not include any sub atomic particles.

The Plum Pudding Model

2. A cloud of positive charge, with negative electrons embedded in it. No protons or Neutrons

Alpha Scattering Experiment

3. Scientists fired alpha particles at a piece of gold foil, they expected the particles to go straight through. Some of the particles bounced back and many were deflected. The scientists suggested that the positive charge and mass of an atom was mainly in the centre and most of the atom was empty space.

Nuclear Model

4. Scientists suggested that electrons orbited the nucleus but not at set distances.

Bohr Model

5. Niels Bohr calculated that electrons orbited the nucleus at set distances called electron shells.

The Proton

6. Further experiments proved that the atoms contained smaller particles called protons which had the opposite charge to electrons.

The Neutron

7. James Chadwick proved that there were particles with no charge called Neutrons which were kept in the nucleus.

Size

8. 1×10*-10