Short Answer Type
Long Answer TypeHow is position of electron and proton in an atom established? Describe an experiment in this regard.
Or
Describe Rutherford's scattering experiment. How did it lead to Rutherford’s nuclear model of atom?
Or
Describe an experiment which provides evidence that most of the charge and mass of an atom is concentrated in its nucleus.
Short Answer TypeLong Answer TypeDiscuss the drawbacks or limitations of Rutherford model of atom.
According to Rutherford’s model, electrons are revolving around the nucleus in circular orbits. The centrifugal force (due to the circular motion of electrons) acting outwards balances the electrostatic force of attraction (between the positively charged nucleus and negatively charged electrons) acting inwards. This prevents the electrons to fall into the nucleus.
It was shown by Clark Maxwell that a charged body moving under the influence of attractive force loses energy constantly. Thus, unlike a planet, electron is a charged particle and it should continuously emit radiation and lose energy. As a result of this, a moving electron will come closer and closer to the nucleus and after passing through a spiral path, it should ultimately fall into the nucleus. It has been calculated that it should take only 10-8 sec for the electron to fall into the nucleus. But it is known that electrons keep on moving outside the nucleus. Hence there must be something wrong with Rutherford's atomic model itself.
This model also fails to explain hydrogen spectrum.
Fig. The orbit becoming smaller and smaller as electron comes closer to the nucleus through spiral path
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