Rutherford Scattering
Physics: AQA A Level, topic 8.1.1
Rutherford Scattering
In the early 20th century Ernest Rutherford conducted an experiment which completely changed our model of the atom.
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'.
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.
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.
Dalton
- In the 1800s, Dalton agreed with Democritus.
- However, he believed that different types of atom corresponded to different elements.
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.
Test yourself on Rutherford Scattering
Which model did Rutherford scattering disprove?
Why did most alpha particles pass through the gold leaf?
Who showed that atoms are not the smallest unit of matter?