Electron Configuration

[melissa_dis4K]

The abbreviated electron confuration of Ni3+ is [Ar]3d^7. Just to clarify even though while I did this I got [Ar]3d^5 4s^2, the electrons in the 4s orbital will move to the 3d orbital to fill that up first. Is this always true or an exception. I.e. will electrons always fill in the previous levels first?

[Blake Salfer 1B]

The 4s2 orbital is filled first, but when ions are formed the s orbital electrons are the first to go because they are at a higher energy state.

[405112316]

The electron configuration of nickel is [Ar]3d^8 4s^2. When you take away 3 electrons to make it Ni3+, you take 2 electrons off of the 4s orbital (highest energy state) and one electron off the 3p orbital. This is not to be confused with considering Ni3+ to be Mn. The electron configuration of Mn is [Ar]3d^5 4s^2. The 4s orbital is filled before the 3d orbital.

[melissa_dis4K]

Thank you! So does this only happen for ions and elements like Cu and Cr?

[Rachel Dang 1H]

Elements like Cr and Cu (and the ones in the same columns) are different in that half full shells and half shells are more stable than not, making their electron configuration [Ar]3d^5 4s^1 and [Ar]3d^10 4s^1. But the concepts described above still are true in that electrons from the outmost energy level (in this case the 4th) will be transferred before an electron from the 3d orbitals.