Name: De Broglie's Explanation of Bohr's Second Postulate
Uploaded: 2019-07-19
Duration: 1 min 30 s
Description: How does one explain Bohr's second postulate of quantisation of orbital angular momentum using de Broglie's hypothesis? Watch this video and find out.

Question

State any two postulates of Bohr&rsquo;s theory of hydrogen atom.

Accepted Answer

Postulates of Bohr’s Hydrogen atom:

1. An atom has a number of stable orbits in which an electron can reside without the emission of radiant energy. Each orbit corresponds, to a certain energy level.

2. An electron may jump spontaneously from one orbit to the other orbit ; then the change in energy in the electron jump is given by Planck’s equation:

$∆ E = E_{2} - E_{1} = hv$

Where $h$ = Planck’s constant, $v$ = frequency of light emitted.

3. The motion of an electron in a circular orbit is restricted in such a manner that its angular momentum is an integral multiple of $h / 2 π$ , Thus

$mvr = nh / 2 π$ ,

4. A special surface around nucleus which contained orbits of equal energy and radius was called shell. The 'energy levels' or 'shells' or 'orbits' are represented in two ways: either by the numbers 1, 2, 3, 4, 5 and 6 or by letters K, L, M, N, O and P. The energy levels are counted from centre outwards.

5. Each energy level is associated with a fixed amount of energy. The shell nearest to the nucleus has minimum energy and the shell farthest from the nucleus has maximum energy. There is no change in the energy of electrons as long as they keep revolving with the same energy level. But, when an electron jumps from a lower energy level to a higher one, some energy is absorbed while some energy is emitted.

State any two postulates of Bohr’s theory of hydrogen atom.

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