Leybold Chemistry Experiments.

The fact that an atom is 'mostly empty' was confirmed by Rutherford, Geiger and Marsden in a momentous experiment. They let a parallel bundle of α-particles fall on a very thin sheet of gold foil. In so doing they found that the vast majority of α-particles pass through the gold foil almost without any deflection at all and only very few are deflected to any large degree. They concluded from this that atoms comprise a nearly massless, extended shell and a massive core concentrated practically at a point.

Experiment C1.1.3.4, carries out an observation with an Am-241-preparation in a vacuum chamber. Depending on the scatter angle ϑ the scatter rate N(ϑ) of the α-particles is measured with a Geiger-Müller tube.