What electron configuration represents an excited state?

1 Answer
Jul 26, 2014

An excited state means that (typically) the valence electron has moved from its ground state orbital (i.e. lowest available energy) to some other higher energy orbital.

So any electron configuration in which the last electron (again, the valence electron) is in a higher energy orbital, this element is said to be in an excited state.

For example, if we look at the ground state (electrons in the energetically lowest available orbital) of oxygen, the electron configuration is #1s^2 2s^2 2p^4#. If the element were to become excited, the electron could occupy an infinite number of orbitals. However, in most texts the example will be the next available one. So for oxygen, it might look like this: #1s^2 2s^2 2p^3 3s^1# - where the valence electron now occupies the 3s orbital in an excited (i.e. not ground) state.