Question

Describe the Bohr model of the hydrogen atom, and explain how Planck's quantum theory contributed to it

Answer 1

Neil Bohr proposed this theory in order to overcome limitations encountered with Rutherford atomic model which cannot explain the stability of an atom.

Bohr's theory is based on the Planck's quantum theory, which explains that the energy of the electromagnetic waves is quantized i.e. gain or los of energy can occur in terms of integral multiples of the smallest unit of energy called a quantum.

Bohr's model can be applied to a hydrogen atom.

Bohr's model of hydrogen model contains three postulates

1. Postulate of circular orbit

2. Postulate of selected orbit

3. Postulate of the origin of spectral lines

1. Postulate of circulate orbit

Electron is revolving in circular path called orbit, around the nucleus. The force required for revolving i.e., centripetal force is provided by the electrostatic force of attraction between negatively charged electron and positively charged nucleus.

Therefore, Centripetal force = electrostatic force

Let m – mass of the electron revolving around the nucleus of radius r at a constant speed v. Let the charge on the electron be -e and charge on the nucleus be +e.