An unknown ion with a charge of +2 has the following electron configuration: [Ar] 4s0 3d7 4p2 What is the identity of the unknown ion?

Answer 1

Cannot solve. need to fill s orbital before you can fill d orbital. Need to also fill d orbital before filling p orbital

Answer 2

This is a tough one. I will assume that there is a misprint and that the electron configuration should read

4s2 3d7 4p2

In that case the answer might be Ga+2

The electron configuration of Ga is [Ar] 4s2 3d10 4p1

The ion has two electrons stripped off: I identify these as coming from the 3d orbital. This would make

[Ar] 4s2 3d8 4p1. This might rearrange itself by shifting an electron from the 3d to the 4p resulting in

[Ar] 4s2 3d7 4p2.

There are some other possibilities, but they don't seem likely.