These quantized energy levels also allow for absorption spectra unique to each element. An electron that is in its lowest energy state is said to be in its ground state. After absorption of energy and promotion to a higher energy level, the electron is said to be in an excited state.
Though the Bohr model is no longer accepted, it contains many valuable features. As is apparent in equation (3), the charge on the nucleus (Z) is inversely related to the radius of an electron's orbit; further, the orbit increases with the square of n.
