Alpha-Scattering and the Nuclear Model

1897: Scientists discovered that atoms contain tiny negative particles called electrons

Plum Pudding Model → an atom is a positive ball of charge with negative electrons embedded in it

To test if the plum pudding model was correct:

1. They got a foil of gold

2. Fired alpha particles at the foil

RESULTS

- Most passed through the gold foil in a straight direction

- A few were deflected

- Some bounced straight back

THESE SHOW THAT

- The atoms are mainly empty space

- The centre of the atom must have a positive charge that repelled the alpha particles

- The mass of the atom is at the centre, which is now called the nucleus

NUCLEAR MODEL

- Mostly empty space

- Positive nucleus in the centre

- Bordered around with electrons

NIEL BOHR

- Electrons orbit the nucleus at specific distances (energy levels/shells)