Cite two important quantum-mechanical concepts associated with the Bohr model of the atom.(b) Cite two important additional refinements that resulted from the wave-mechanical atomic model.

Bohr postulated that electronic energy levels are quantized. Secondly, a photon of light of a particular frequency is emitted when electrons move from a higher to a lower energy levels.

Explanation:

The Bohr model of the atom is the immediate predecessor of the wave mechanical model of the atom. The wave mechanical model refined the Bohr's model by treating the electron as a wave having a wave function psi. The wave function describes the identity of the electron. From Heisenberg uncertainty principle, the position of a particle cannot be accurately and precisely measured. Hence the wave mechanical model added that electrons are not localized in orbits according to Bohr's model but the integral of psi squared dx gives the probability of finding the electron within a given space.