2A.19 7th edition

[Katie Frei 1L]

Hello! Could someone please explain to me why for part e) of this question the electron configuration of Ni^+2 is [Ar]3d^8 instead of [Ar]3d^6 4s^2. Thank you!

[Lumbini Chandrasekera 1B]

I think it [Ar] 3d^8 because lower principle energy levels should be filled with electrons first before the next energy level (n=4) is filled which is why it wouldn't be [Ar] 3d^6 4s^2.

[Nicole Lee 4E]

Electrons are removed from the 4s orbital before 3d electrons are removed, so you get [Ar]3d^8 instead of [Ar]3d^6 4s^2.

[Theodore_Herring_1A]

The electrons are removed from the 4s orbital before 3d when forming ions. This is because electrons are always removed from the outermost orbital first, in this case 4s. This is why it is [Ar]3d8 and not [Ar]3d64s2.