Limitations of Bohr Model:

Bohr model has many limitations. Some are given here:

1. The Bohr model is applicable to hydrogenic atoms. It cannot be extended even to more two electron atoms such as helium. The analysis of atoms with more than one electron was attempted on the lines of Bohr’s model for hydrogenic atoms but did not meet with any success. Difficulty lies in the fact that each electron interacts not only with the positively charged nucleus but also with all other electrons.

2. It does not explain why only circular orbits should be chosen when elliptical orbits are also possible.

3. In the spectrum of hydrogen, certain spectral lines are not single lines but a group of closed lines with slightly different frequencies. Bohr’s theory could not explain these fine structures of the hydrogen spectrum.

4. Bohr’s theory does not tell anything about the relative intensities of the various spectral lines. Bohr’s theory predicts only the frequencies of these lines.

5. It does not explain the further splitting of spectral lines in a magnetic field (Zeeman effect) or in an electric field (Stark effect).

6. The formulation of Bohr model involves electrical force between positively charged nucleus and electron. It does not include the electrical forces between electrons which necessarily appear in multi-electron atoms.