## Problem 3.5

Dayna Pham 1I
Posts: 98
Joined: Fri Sep 28, 2018 12:16 am
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### Problem 3.5

Hello! Here is Problem 3.5:
3.5 Give the ground-state electron confi guration expected for each of the following ions: (a) Cu+; (b) Bi3+; (c) Ga3+; (d) Tl3+.

Regarding part a, for Cu+, why does the electron configuration go one more element to the right on the periodic table, when it loses one electron? I thought it goes one more to the left, since it loses one electron and takes on the configuration of Nickel?

The solutions manual said it is [Ar] 3d10.

Jeannine 1I
Posts: 73
Joined: Fri Sep 28, 2018 12:27 am

### Re: Problem 3.5

The ground state electron configuration for Cu would be [Ar]4s^1 3d^10. You would think it would be [Ar]4s^2 3d^9, but a full d-orbital is more favorable than a full s-orbital. This means one electron in the s-orbital will jump to the d-orbital in order for that orbital to be full.

So in Cu+, the electron removed comes from the s orbital since it is easier to remove 1 electron from the s-orbital than to remove 1 electron from a full d-orbital. The config for Cu+ then becomes [Ar]3d^10.

A general rule to know when removing electrons from an atom that has a d-orbital, is to remove electrons first from the s-orbital.