Question
How will you explain the observations of Rutherford's α-ray scattering experiment?
Solution
(i) Most of the space in an atom between the nucleus and revolving electrons is empty. So most of α-particles will pass through an atom without any deflection. Electrons may cause only minor deflections to α-particles.
(ii) Alpha particles (He2+) have two units of positive charge while the nucleus of gold contains 79 protons. The nucleus will repel the α-particles. Since the size of the nucleus is very small, so only a few α-particles will pass by its side and deflected by a small angle.
(iii) A very few α-particles (1 in 20000) may hit or try to hit the small nucleus and these will be deflected backwards through angles greater than 90°.
