Bohr’s Atomic Model

In 1913, Niels Bohr proposed his quantized shell model of the atom to explain how electrons can have stable orbits around the nucleus.
The atom only has certain energy levels, they are determined by fixed circular orbits of electrons around the nucleus.
An atoms energy does not change while the electron moves in a particular orbit.
Electron changes to another energy level (orbit) by absorbing or emitting a photon.