|Class 11 Chemistry Structure of Atom||Explanation of Hydrogen Spectra|
EXPLANATION OF HYDROGEN SPECTRA
According to Bohr,
The wavelength emitted by them can be calculated as:
Limitations of Bohr model of an atom:
This led to the discovery of Quantum mechanics. Let us first understand the dual nature of matter and Heisenberg uncertainty principle that couldn’t be explained by Bohr model.
DUAL NATURE OF PARTICLE: DEBROGLIE AND HEISENBERG UNCERTAINTY PRINCIPLE
As we have studied that light has dual character .That is particle as well as wave character. In the same way, it was proved that all material particles too have wave like character.
It was explained by De-Broglie: According to him when any particle is in motion it emits wave.”
The wavelength associated with it is given by:
Significance of De- Broglie relation
In real life, it does not have any significance. This is because in real life we come across only macroscopic objects which have significant mass. So, the wavelength emitted by them is almost nil. The wavelength is significant only for microscopic bodies, but in real life we do not come across microscopic objects.
Derivation of Bohr postulate of angular momentum from de Broglie relation
According to Bohr model, the electron move around the nucleus in circular orbit. According to De Broglie, the wave can be in phase or can be out of phase. For the wave to be in phase the circumference should be integral multiple of wavelength that is:
Hence it also derives the postulate of bohr’s model.
Problem : Calculate the mass of a photon with wavelength 3.6A