Rutherford’s nuclear model of an atom considers an atom to consist of a positively charged nucleus with electrons revolving around it. The electrons and the nucleus in an atom are held together by electrostatic force of attraction.
Because of the presence of electrostatic attraction between the nucleus and the electrons, the electrons should fall into the nucleus. But it does not happen. In order to explain this, Rutherford postulated that the electrons are not stationary, but are revolving around the nucleus, and the attractive forces between the nucleus and electrons are balanced by the centrifugal force acting only the moving electrons.
The Rutherford’s model explains the structure of atom in a very simple way. But, it suffers from the following drawbacks.
1. An electron revolving around the nucleus gets accelerated towards the nucleus. According to the electromagnetic theory, an accelerating charged particle must emit radiation, and lose energy. Because of this loss of energy, the electron would slow down, and will not be able to withstand the attraction of the nucleus. As a result, the electron should follow a spiral path, and ultimately fall into nucleus. If it happens then the atom should collapse in about 10-8 second. But, this does not happen: atoms are stable. This indicates that there is something wrong in the Rutherford’ mass nuclear model of atom.
2. The Rutherford’s model of atom does not say anything about the arrangement of electrons in an atom.