Final answer:
Bohr's model of the atom, based on the photo emission spectra, proposed that electrons occupy specific energy levels and emit photons when moving between these levels, resulting in a unique atomic spectrum for each element.
Step-by-step explanation:
In 1913, using the photo emission spectra as evidence, Niels Bohr proposed a new model for the atom which incorporated the novel idea that electrons occupy specific energy levels. Bohr's model theorized that an atomic spectrum is produced when electrons move between these levels. When electrons are given energy, they can jump from their ground state to an excited state. Upon returning to a lower energy level, they emit energy in the form of light or photons. The spectrum produced consists of discrete lines, each corresponding to a specific transition between energy levels, which is why each element has a unique atomic spectrum.
Bohr's model was a pioneering step in quantum theory, combining elements of classical mechanics with quantum hypotheses to explain phenomena that previous atomic models, such as Rutherford's, could not. His idea of quantized energy levels helped to explain the stability of the atom and the discrete nature of atomic spectra, which was a significant advancement in the understanding of atomic structure at the time.