Bohr's Model
This model was proposed in 1913 by Niels Bohr and was really an expansion on the Rutherford model of 1911. The Rutherford model had several flaws that the Bohr model overcame. Bohr’s model proved that electrons orbit around the nucleus as set distances. When the electron changes orbit, it does so in a what is called a quantum leap. The model was based on his observations of the atomic emissions spectrum of the hydrogen atom. When white light is diffracted with a prism, all the colors of the visible spectrum can be seen. Each color corresponds to a specific amount of energy; however when the light given off by the hydrogen atom it passed through a prism, only certain colors of light could be seen. By seeing this Bohr theorized that electrons only have certain energies in an atom and that they had to be on energy levels. Bohr said that the electron had to release energy to change its energy so the differences between the energies of light seen in the atomic spectrum should correspond to the differences in energies of the energy levels.