Bohr's Postulates & observations of hydrogen spectrum?

Question

How did Bohr's postulates explain observations and measurements of the hydrogen gas spectrum?

Can someone please tell me briefly, but in relation to the postulates?

For example, his first postulate helped explain the observation of the hydrogen gas spectrum that electrons could only exist at certain values?

Thank you very much!!

Answer 1

Bohr’s first postulate states that atoms have well defined orbits, and that electrons revolve around the nucleus in a circular fashion. This postulate keeps the basic structure of the atom, which successfully explains the results of Rutherford’s alpha particle-scattering experiments.

Bohr’s second postulate states that orbital angular momentum is a quantized value – there are only certain values for which orbit is possible. This postulate was required to account for the atomic emission spectra of Hydrogen. It was only when the orbits were separated according to this postulate that gave the observed results, thus explaining the experimentally observed spectra. The third postulate says that electrons in stable orbits, or ‘stationary states’, do not emit energy.

Bohr’s third postulate accounts for the observed stability of matter – that atoms constantly remained stable unless they were not in stationary states, which would cause them to emit energy.

Bohr’s fourth and final postulate states that electrons can change orbits, but in the process, it must absorb or release some energy. This postulate explains how atoms give off and take on certain frequencies of electromagnetic radiation. It states that electrons in the lowest energy state, or ground state, can only jump to a higher energy shell within the atom when given a certain amount of energy by absorbing that energy from a photon of electromagnetic radiation – explaining the observations of Hydrogen as it changed energy shells.