In the “Atomic Structure” unit, you learned about Bohr’s Model, which states that electrons can absorb energy to jump up energy levels.
An electron that has absorbed energy and jumped up an energy level is in its excited state. Electrons at their original energy level are in the ground state.
When an atom is excited, its electron configuration will be slightly different. This is because electron(s) are changing subshells.
Ex. Ground state carbon has an electron configuration of 1s² 2s² 2p². If an electron from 2s absorbs the correct amount of energy, it jumps to 2p, resulting in the new configuration: 1s² 2s¹ 2p³.
The diagram below helps visualize this ↴
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