Which scientist proposed the nuclear model of the atom?
The nuclear (or planetary) model was proposed by E. Rutherford. Its appearance in 1911 was preceded by experiments with colleagues in which alpha particles were aimed at a thin foil of gold and other metals. It was found that most of the alpha particles penetrate the target relatively freely. It was difficult to explain the fact that a small part of the particles are deflected at large angles, and sometimes even reflected back. From this, the following conclusions were drawn: – the nucleus has a very small volume in comparison with the atom; – the mass of the nucleus is almost equal to the mass of the atom, electrons account for fractions of a percent; – at a great distance from the nucleus, electrons revolve (like planets around the Sun); – the positive charge of the nucleus is exactly compensated by the total charge of the electrons, that is, the atom is electrically neutral.