energy level One of a set of states of a physical system associated with a range of energies. Electrons in an atom, for example, can shift between the different energy levels corresponding to orbitals in different shells. Also called energy state. |
in physics, any discrete value from a set of values of total energy for a subatomic particle confined by a force to a limited space or for a system of such particles, such as an atom or a nucleus. A particular hydrogen atom, for example, may exist in any of several configurations, each having a different energy. These energy states, in their essentials, remain fixed and are referred to as stationary states.