Textbook Problem 2A.5

[006399734]

Textbook problem 2A.5 essentially asks for the electron configuration of Zn, which I believed would be (Ar)3d^8 4s^2, since, the 4s orbital is supposed to fill up first, but the answer is supposed to be (Ar)3d^10. Can anyone explain the reasoning behind this? Thank you

[Praise Yu 1C]

When cations form, valence electrons in the p-orbital are removed first, and then the electrons from the s-orbital, and then d-orbitals. Thus, you would remove the electrons from the 4s orbital before removing electrons from the 3d orbital.