Shortcomings of Rutherford atomic model: Rutherford proposed planetary model of atom in which electrons revolve round the nucleus.
An electron revolving round the nucleus has an acceleration directed towards the nucleus. Such accelerated electron must radiate electromagnetic radiation.
But, if an revolving electron radiates energy, the total energy of the system must decrease. In such situation, the electron must come closer to the nucleus and hit the nucleus. Also, the radiation spectrum of emitted electromagnetic waves should be continuous.
However, this does not happen in an atom. Atom is not unstable and the spectrum is not continuous. Rutherford atomic model cannot explain these two observations. These are the shortcomings of Rutherford Atomic Model.
To overcome this discrepancy, Neils Bohr put forward three postulates combining classical physics and Planck's quantum hypothesis.
Bohr's 1‌st ‌ postulate provides stability to the atomic model.
Bohr's 2‌nd ‌ postulate provides justification that electrons may revolve in stationary orbit.
Bohr's 3‌rd ‌ postulate provides the explanation of line spectrum.