## 2A.11 7th Edition

Vikramjeet Gill 1C
Posts: 30
Joined: Fri Sep 28, 2018 12:15 am

### 2A.11 7th Edition

Which M^3+ ions (where M is a metal) are predicted to have the following ground state electron configurations
a) [Ar]3d^6
b)[Ar]3d^5

I can't seem to understand how to solve these questions, can someone explain how they would get to the answer.

Elisa Bass 4L
Posts: 61
Joined: Fri Sep 28, 2018 12:23 am

### Re: 2A.11 7th Edition

The problem is asking you to find the metal 3+ ion with the given electron configuration. In the case of the first problem, [Ar]3d^6, you can see that the ion has lost both electrons from the 4s orbital, as the 4s orbital fills before the 3d but has not been written on the ground state configuration. Additionally, because the charge of the metal ion is 3+, it has to have lost an additional electron, which must have therefore come from the 3d orbital to make the ion have a configuration of 3d^6. If you look at the periodic table, you see that Co normally has a configuration of [Ar]3d^7,4s^2 and that if it were to lose 3 e-, it would have a new configuration of [Ar]3d^6.

A good explanation of this can be found on page 69 of the 7th Ed. Textbook.