Ernest Rutherford – The nuclear atom
Today we’re going to be looking at Rutherford’s alpha-particle scattering experiment and how, through this, he found ground-breaking new evidence on the structure of a nuclear atom.
Ernest Rutherford, a notable English physicist, in the 20th century understood that all matter is made up of atoms. However, he wanted to delve deeper in this understanding about atoms. As a result in 1909, along with his assistants, Hans Geiger and Ernest Marsden, carried out an experiment to investigate a detailed model for the atom (the ‘inner-workings’).
Diagram of Rutherford’s Alpha-Particle Scattering Experiment
What Rutherford did was quite unique. He used and a He used a source which emitted alpha particles (charged helium ions), and directed the beam of alpha particles towards a thin gold foil (he wanted a thin layer as thin a layer as possible) to observe any effects between the two.
- Roughly 99% of the alpha particles passed straight through the foil.
Some of the alpha particles were deflected by the foil at small angles - 1 in 8000 alpha particles were deflected at around 90° and over.
- Around one out of every 12000 particles to rebounded off the gold foil – some directly in the opposite direction!