Rutherford Scattering  (Gold Foil, Leybold)

The Rutherford scattering experiment with a thin layer of gold 2 micrometers thick was an important experiment in understanding atomic structure. In this experiment, alpha (positively charged) particles were fired towards a very thin layer of gold. Most of the alpha particles passed through the layer without deflection, but some were scattered at large angles, and some were even reflected almost back. This result was surprising and could not be explained by Thomson's atomic model at the time. Rutherford concluded that atoms have a small, dense, positively charged nucleus, where most of the atomic mass is concentrated. This finding became the basis for the modern atomic model and was the first experimental evidence of the existence of atomic nuclei. The selection of gold (Z = 79) allowed the large scattering effect to be more easily observed because gold nuclei have a large charge.