Question

Which of the following is not explained by Bohr’s atomic model?
(A) Zeeman Effect.
(B) Stark Effect.
(C) Both A and B.
(D) The angular momentum of electron is the integral multiple of $\dfrac{nh}{2\pi }.$

Answer 1

Hint : We know that Niels Bohr was the first to explain quantitatively the general features of hydrogen atom structure and its spectrum. According to his model, it is considered that the electron in the atom moves in a circular orbit.

Complete Step By Step Answer:
Niels Bohr was the Danish physicist that works on the hydrogen atom and demonstrates the structure and spectrum of this atom. He had given some postulates on which his model is completely based. These are:
- The electron in the hydrogen atom can move around the nucleus in a circular path having fixed radius and energy. These paths are called orbits. These orbits are arranged concentrically around the nucleus in which the electron moves.
- The energy of an electron that is present in the orbit does not change with time. However, the electron will move on the basis of energy, that means the electron moves from a lower stationary state to higher stationary state when it absorbs the energy or when it emits the energy, electron moves from higher energy state to lower stationary state.
- The frequency of radiation gets absorbed or emitted when transition occurs between two stationary states. This is measured by the difference in energy and is expressed by the expression i.e. commonly known as Bohr’s frequency rule.
Whereas, In the Zeeman Effect, the orbitals shift up and down in energy depending on the magnitude and the sign of the magnetic quantum number. In stark effect the shift depends only on the magnitude of the magnetic quantum number. The resulting spectral lines depend on the relative size of the field induced splitting compared to the separation between the multiples. The Bohr model could not explain those atoms which have more than one electron like lithium, helium. This model was applicable only for those atoms which have one electron.
Bohr Theory explained only spherical orbits. There was no explanation for elliptical orbits. This model failed to explain Zeeman Effect and Stark effect. The Bohr model could not explain the uncertainty principle of Heisenberg. The Bohr model was not related with classification and periodicity of elements. By using the Bohr atomic model, one can’t explain the intensity of the spectrum line.
Therefore, the correct answer is option C.

Note :
Remember that the behavior of the electrons as particles and waves is given by Louis De Broglie. According to him, the electrons exhibit dual nature i.e. having both particles as well as wave-like properties. This means that like the photon, electrons too have wavelength as well as momentum.