Final answer:
An atom in an excited state has an electron configuration where one or more electrons occupy higher energy orbitals than in the ground state. For instance, an excited hydrogen atom could have an electron in the 2s or 2p orbital, as opposed to the 1s orbital of its ground state.
Step-by-step explanation:
An electron configuration that represents an atom in an excited state will have one or more electrons in a higher principal quantum shell or subshell than in the ground state. Instead of having electrons occupy the lowest energy levels (orbitals) in sequential order as per the Aufbau principle, an excited electron jumps to a higher energy level. For example, the ground state electron configuration for a hydrogen atom is 1s1. If the hydrogen atom absorbs energy, the electron may move to the 2s or 2p orbital, resulting in an excited state configuration such as 1s02s1 or 1s02p1. The shells and subshells of an atom are depicted in orbital diagrams that show the individual orbitals and the pairing arrangement of electrons. Excited electrons in these diagrams will be depicted in higher energy orbitals compared to their ground state counterparts. Remember, an excited state is generally unstable, and the electron will likely return to the ground state, releasing energy in the form of light or other electromagnetic radiation.