Write the main postulates of Rutherford's atomic model and cause of failure of this model.

Explanation

On the basis of the result of a-scattering experiment, Rutherford suggested the following picture of the atom :
I. An atom may be regarded as a sphere of diameter I0~l0 m but whole of the positive charge and almost the entire mass of the atom is concentrated in a small central core called nucleus, having a diameter of about 10~14 m.
.2. The nucleus is surrounded by electrons. In other words, the.electrons are-spread over the remaining part of the atom, leaving plenty of empty space in the atom.
3. As the atom is electrically neutral, the total positive charge on the nucleus is equal to the total negative charge of the electrons in the atom.
4. Rutherford pointed out that the electrons inside the atom are not stationary for if they were at rest, they would pulled into the positive nucleus due to the strong electrostatic force of attraction between the nucleus and the electrons. He assumed that the electrons are revolving around the nucleus in circular orbits, the necessary centripetal force being provided to them by the electrostatic force of attraction between the electrons and the nucleus.