8.1.1

Rutherford Scattering

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Rutherford Scattering

In the early 20th century Ernest Rutherford conducted an experiment which completely changed our model of the atom.

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The experiment

  • Rutherford conducted an experiment where he fired alpha particles at a very thin piece of gold leaf.
  • The particles mostly passed through the gold leaf, but some were deflected at large angles.
  • This was not expected and disproved the 'plum pudding model'.
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Explanation of results

  • The strong deflections were caused by electrostatic repulsion between the positive nucleus and the positive alpha particles.
  • Most alpha particles passed through as the atom is mostly free space.
  • This new theory became our current model of the atom, a positive nucleus with negative electrons in orbit.

Our Knowledge of the Atom

Over time, with various experiments, we have discovered more about the atom and the nucleus.

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Democritus

  • In the 5th century BC, Democritus suggested that matter was made of lumps called atomos.
  • All atomos were believed to be identical.
  • The atomo was considered the smallest possible unit of matter.
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Dalton

  • In the 1800s, Dalton agreed with Democritus.
  • However, he believed that different types of atom corresponded to different elements.
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Thomson

  • Thomson discovered that electrons could be removed from atoms.
  • This showed that atoms were not the smallest units of matter.
  • Thomson believed that atoms were clouds of positive charge with negative electrons suspended inside.
    • This was called the plum-pudding model.
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Rutherford

  • Rutherford used his famous scattering experiment to show that atoms consist of a positively charged nucleus with orbiting negatively charged electrons.
  • This is the current day model of the atom.

Jump to other topics

1Measurements & Errors

2Particles & Radiation

3Waves

4Mechanics & Materials

5Electricity

6Further Mechanics & Thermal Physics (A2 only)

7Fields & Their Consequences (A2 only)

8Nuclear Physics (A2 only)

9Option: Astrophysics (A2 only)

10Option: Medical Physics (A2 only)

11Option: Engineering Physics (A2 only)

12Option: Turning Points in Physics (A2 only)

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