Question

What is the electron configuration of Gallium in its excited state?

Hey Team,
just started chemistry a few weeks ago and am learning about electron configuration currently. I am a bit confused on how excited state atoms work.
I know that the electron configuration of Gallium is : 〖3d〗^10 〖4s〗^2 〖4p〗^1
However am not to sure what its configuration would be in an excited state since it only has one valence electron.

Thank you for your help !!!

Answer 1

`["Ar"]"3d"^10"4s"^1"4p"^2"`.

Explanation:

Do take note, before we begin, you must write Ar before the last few `spdf` electronic configurations because Ar's electronic configuration replaces writing out all of the `spd` electronic levels before reaching 3d10.

When you draw out the electronic box diagram, you will notice that the last, highest energy sub-orbital (that is, 4p) has a few empty boxes as I will try to illustrate below.
4s2 [`uarrdarr`] 4p1 [`uarr`] [ ][ ]

When you have an atom in an excited state, electrons on the highest energy level (which will be 4) can spread out among all the sub-orbitals on that energy level.
This means that energy level 4 will become something as below.
4s1 [`uarr`] 4p2 [`uarr`] [`uarr`] [ ]

This is due to VSEPR (Valence Shell Electron Pair Repulsion Theory). This theory states that electrons will try to fill out all of the sub-orbitals before finally pairing up on the lowest energy level sub-orbital. However, in an excited state, electrons will not pair up and will continue to occupy single sub-orbitals, but take note that this only happens with the valence shell electrons.

Referring to the electron box diagrams above, gallium will, therefore, be in Group 13, having three valence electrons to bond with.

Hence, to answer your question, gallium's electronic configuration in its excited state is `["Ar"]"3d"^10"4s"^1"4p"^2"`.