Asked by Sambit kumar Sahoo | 22nd Jun, 2013, 11:29: PM

Expert Answer:

Bohr's model for hydrogen atom:

1. An electron in the hydrogen atom can move around the nucleus in a circular path of fixed radius and energy. These paths are called orbits or energy levels and are numbered in terms of Principal Quantum numbered as n=1, 2, 3…These orbits are arranged concentrically around the nucleus.2. As long as an electron remains in a particular orbit, it does not lose or gain energy and its energy remains constant.

3. When transition occurs between two stationary states that differ in energy, the frequency of the radiation absorbed or emitted can be calculated.

4. An electron can move only in those orbits for which its angular momentum is an integral multiple of h/2pi

5.  The radii of the stationary states is expressed as rn = n2ao where ao= 52.9 pm

6. The energy of stationary state:

Limitations of Bohr's model of atom:
  1. It failed to account for the finer details of the hydrogen spectrum. For instance, splitting of a line in the spectrum into two closely spaced lines.
  2. It was also unable to explain spectrum of atoms containing more than one electron.
  3. It was unable to explain Zeeman Effect i.e. splitting of spectral line in presence of magnetic effect.
  4. It also failed to explain Stark effect i.e. splitting of spectral line in presence of electric field.
  5. It could not explain the ability of atoms to form molecules by chemical bonds

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Answered by  | 26th Jun, 2013, 11:03: AM

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