The Rutherford scattering experiment was conducted in 1911 by Ernest Rutherford, Hans Geiger, and Ernest Marsden to investigate the structure of the atom. The experiment involved firing alpha particles (helium nuclei) at a thin gold foil and observing their scattering pattern.
1. Equipment: To conduct this experiment, a radioactive source that emits alpha particles was used. The alpha particles were directed towards a very thin sheet of gold foil, which was only a few atoms thick. The apparatus used to detect the scattering of alpha particles was a screen coated with zinc sulfide (ZnS) that glowed when struck by the alpha particles.
2. Theory: Rutherford and his team hypothesized as to the nature of the atom. The plum pudding model of the atom, proposed by J. J. Thomson, was a popular model at the time. In this model, the atom was thought to be made up of a positively charged "pudding" with negatively charged electrons scattered throughout. Rutherford believed that this model failed to explain his own experiments.
3. Experiment: The experiment began by releasing alpha particles from the source. The alpha particles were directed towards the gold foil at different angles, and the scattered alpha particles were detected on the screen behind the foil. The number and angle of scattered alpha particles were recorded.
4. Results: The results of the experiment showed that most of the alpha particles passed straight through the gold foil unaffected. However, some alpha particles were scattered at large angles, and a small fraction (about one in 8,000) were scattered almost backward.
5. Conclusion: The Rutherford scattering experiment showed that the atom was mostly empty space, with a tiny nucleus at the center that contained all the positive charge of the atom. This provided evidence that the plum pudding model was incorrect and paved the way for further experiments that led to the development of the modern atomic model.
outline the rutherford scattering experiment.
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