physics

In Ernest Rutherford’s model of the atom (also known as the nuclear model), the atom consists of a small, dense, positively charged nucleus surrounded by a cloud of electrons. According to this model, when an alpha particle (which is a cluster of two protons and two neutrons) is directed at a gold leaf, some of the alpha particles will be scattered in the opposite direction due to the fact that the positively charged nucleus in the atom will repel the alpha particle. Since both the nucleus and the alpha particles are positively charged, the alpha particle will be repelled directly away from the nucleus as it approaches it, resulting in the back-scattering.