In his famous experiment, Rutherford bombarded a thin sheet (0.00006 cm thick) of gold foil with alpha (α-) particles in an evacuated chamber. A simplified picture of α-particle scattering by thin gold foil.
The following observations were made on the results obtained.
(i) Most of the α-particle passed through the foil straight without suffering any change in their direction.
(ii) A small fraction of α-particles were deflected through small angles, and a few through larger angles.
What conclusions were derived from the scattering experiment
The following conclusions were drawn from the Rutherford’s scattering experiment.
1. Most of the α- particles passed straight through the foil without suffering any deflection. This shows that most of the space inside the atom is empty or hollow.
2. Some of the α- particles suffered deflection by 90° or even larger angels. For this to happen α- particles (positively charged) must approach a heavy positively charged core inside the atom (Like charges repel each other). This heavy positively charged ‘core’ inside the atom was named as nucleus.
3. Since the number of α- particles which bounced back was very small, hence, the volume occupied by the nucleus is very small as compared to the total volume of the atom.
4. The α- particles have appreciable mass. These are deflected by the nucleus. It means that almost the entire mass of the atom lies at its center, i.e., entire mass of an atom is concentrated inside its nucleus.