## HW 2A.5

Jessica Chen 2C
Posts: 103
Joined: Thu Jul 11, 2019 12:17 am

### HW 2A.5

Why do we take electrons from the s orbital rather than the d orbital? As in, why is the Ga3+ ion [Ar]3d^10 rather than [Ar]3d^8 4s^2?

Hiba Alnajjar_2C
Posts: 108
Joined: Fri Aug 09, 2019 12:17 am

### Re: HW 2A.5

When removing electrons to form an ion, you remove electrons from the outermost shell. In this case, that's the 4th shell (n=4), which is occupied by 2 electrons in the 4s orbital and 1 electron in the 4p orbital. As a result, you remove these three electrons before removing any from 3d.

205296774
Posts: 66
Joined: Thu Jul 25, 2019 12:15 am

### Re: HW 2A.5

My TA explained it like this:

Always write out the complete ground state, then move backwards subtracting electrons from right to left. So for this one, begin with [Ar]3d^10 4s^2 4p^1. Then, move from right to left, taking away the 4p and 4s orbitals to get a positive charge of 3. Technically, because of stability reasons, 3d is before 4s so when altering the ground state, remove those first.

Hope this helps.