## Exceptions when writing e- configurations

Anna Nordstrom 1A
Posts: 15
Joined: Fri Sep 25, 2015 3:00 am

### Exceptions when writing e- configurations

The electron configuration for Copper is an exception so it is [Ar]3d^10 4s^1. If Copper gained an electron, would it be added back to 4s to make it [Ar]3d^10 4s^2? Also, in lecture we were discussing how if you lose an electron, you remove the most recent electron you drew or the outermost e-. Does this rule also apply to our exceptions, Copper and Chromium?

Yvonne Tran 2F
Posts: 30
Joined: Fri Sep 25, 2015 3:00 am

### Re: Exceptions when writing e- configurations

Anna Nordstrom 1A wrote:The electron configuration for Copper is an exception so it is [Ar]3d^10 4s^1. If Copper gained an electron, would it be added back to 4s to make it [Ar]3d^10 4s^2? Also, in lecture we were discussing how if you lose an electron, you remove the most recent electron you drew or the outermost e-. Does this rule also apply to our exceptions, Copper and Chromium?

Copper is metal, so it tends to lose electrons and form cations because of its lower ionization energies. Copper wouldn't gain an electron.
The rule you mentioned also applies to the exceptions. For example, Cu+ would lose its electron in the 4s orbital because it's an unpaired electron, so that electron is more easily removable. Cu+ would be [Ar]3d^10

Tanera van Diggelen 4G
Posts: 21
Joined: Fri Sep 25, 2015 3:00 am

### Re: Exceptions when writing e- configurations

If copper were to gain an electron, I assume that the gained electron would occupy the 4s orbital. This is because the 3d orbital is filled up, so the open orbital with the next lowest energy is the 4s orbital, as seen when you write out the electron configuration for Copper in its ground state.
Remember that electrons must occupy the lowest available energy state.

Christopher Lew 1L
Posts: 20
Joined: Fri Sep 25, 2015 3:00 am

### Re: Exceptions when writing e- configurations

On the off chance that copper does gain an electron, the electron will fill the 4s orbital. I believe Tanera is correct as it does make sense that the 3d orbital is filled up at that point and that the orbital continue to fill the lowest available energy states. In addition, she does pose a very good point that we should remember the electrons will fill orbitals with the lowest available energy state.

On a side note, I wonder if we should look to the next element's electron configuration as to where the electron should go. I know that orbitals of different elements have unique behaviors, but could they help us with the configurations?