In order to explain the limitations of Rutherford’s atomic model, in 1913 Niels Bohr put forward a theory for the hydrogen atom based upon quantum theory for which he was awarded a “noble prize.”
Though Bohr’s Theory can successfully explain the spectra of the Hydrogen atom, it is suffered from the following limitations.
Limitations of Bohr’s Theory
6 Major limitations of Bohr’s Theory are…
- This theory cannot explain the fine-line structure of the spectrum of the hydrogen atom. Because if the hydrogen spectrum is observed with a high-resolution spectrometer, it is found that, some of the lines split into fine lines.
- Bohr’s theory can not explain the Zeeman effect and Stark effect i.e. splitting of fine lines into super fine lines under the influence of the electric and magnetic field.
- Bohr’s theory can only explain the spectra of hydrogen atoms like one electronic system e.g. He+, Li2+, Be3+, Ne9+, etc. However, the theory fails to explain the spectra of multi-electronic systems like Li, Be, N, F, etc.
- Bohr’s Theory contradicts the Heisenberg – Uncertainty Principle which states that “It is impossible to determine both the position and momentum (or velocity) of an electron simultaneously and accurately.
- There was no justification for the assumption that the electron can only be rotated only in those orbits in which the angular momentum of the electron should be
. Where h=plank’s constant. - Bohr’s theory considered that the nucleus is stationary except for rotating on its own axis. This would be true if the mass of the nucleus were infinity. The nucleus actually oscillates slightly about the center of gravity and to allow for this the mass of the electron ‘m’ should be replaced by reduced mass ‘
. Where h=plank’s constant.
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