In the Rutherford's Alpha rays scattering experiment...... What  happened when the alpha rays hit the electrons present in the gold atom?
 

Dear student
Ernest Rutherford, while performing experiments on radioactivity, bombarded fast moving alpha particles on a thin gold foil (about 1000 atoms thick). He selected the gold foil because of its high ductility; and doubly charged alpha particles because of their large amount of energy. He expected to see small deflections of alpha particles by the sub-atomic particles present in gold atoms. The following figure shows the set-up of his experiment.

From the experiment, he made the following observations:

1. Most of the fast moving α-particles passed straight through the gold foil.
2. Some α-particles were deflected through the foil by small angles.
3. Surprisingly, one out of every 12,000 particles rebounded i.e., they got deflected by an angle of 180º.

Rutherford derived the following conclusions from the gold foil experiment:

1. Since most α-particles passed through the gold foil without any deflection, most of the space inside an atom is empty.

2. Very few particles suffered a deflection from their path. This means that positive charge occupies very little space inside an atom.

3. As a small fraction of particles got deflected completely by the angle of 180º, all positive charge and mass of gold atoms are present within a very small volume inside the atom.

Based on the above conclusions, Rutherford gave a new atomic model known as the Rutherford atomic model or nuclear model of the atom. The major features of the model are as follows.

1 All protons are present inside the nucleus, which is situated at the centre of the atom.

2. Electrons reside outside the nucleus and revolve around the nucleus in well-defined orbits.

3. The size of the nucleus is very small in comparison to the size of an atom. As per Rutherford’s calculations, the size of the nucleus is 10⁵ times smaller than an atom.

4. As the mass of the electron is negligible in comparison to the mass of the proton, almost all the mass of the atom is concentrated in the nucleus.

Hope it is clear
Regards