What experimental evidence leads scientists to believe that only quantized electronic energy states exist in atoms?

Bohr atomic model. The most important experiment in proving the theory of the amount of energy states in an atom was when Bohr tested the motion of the electron in the hydrogen atom which was not possible in Rutherford's previous experiment. Bohr's principles were: 1- Each electron has an amount of energy 2- Electrons have an orbit and the more energy farther from the nucleus 3- The more energy the more energy from the electron increases 4-Each electronic layer has a number and are represented by the letters K, L, M, N, O, P, Q.