Electrons within an atom occupy certain discrete energy levels. Absorbing light energy of specific frequencies causes an electron to jump to a higher energy level. In releasing this energy, the electron falls back to a lower energy state. The electron cannot occupy levels between these quantized energy levels. These energy levels can be calculated by
Where h is Planck's constant, R is the Rydberg constant = .
The energy levels of hydrogen are specified by the principle quantum number n. When an electron falls from a higher energy level to a lower one, it emits a photon of energy. The energy and frequency of the photon are given by
