Question

What are the various postulates of Bohr's model of atom? Discuss its drawbacks.

Accepted Answer

Postulates of Bohr’s Model of an Atom:

1. In an atom, the electrons revolve around the nucleus in certain definite circular paths called orbits, or shells named as $K, L, M \dots . .$

2. Each shell or orbit corresponds to a definite energy. Therefore, these circular orbits are also known as energy levels or energy shells.

3. The energy of an orbit is quantized. Since, electrons can be present only in these orbits, hence, these electrons can only have energies corresponding to these energy levels, i.e., electrons in an atom can have only certain permissible energies.

4. The electrons present in an atom can move from a lower energy level to a level of higher energy by absorbing the appropriate energy. Similarly, an electron can jump from a higher energy level to a lower energy level by losing the appropriate energy.

Drawbacks of Bohr’s Model of an Atom

It violates the Heisenberg Uncertainty Principle. The Bohr atomic model theory considers electrons to have both a known radius and orbit, that is, known position and momentum at the same time, which is impossible according to Heisenberg.

It failed to explain the Zeeman effect and Stark effect.

What are the various postulates of Bohr's model of atom? Discuss its drawbacks.

Important Questions on Structure of Atom

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