what is the electron configuration of Fe2+

[Smooth Operater]

The correct answer is..

1s2 2s2 2p6 3s2 3p6 4s1 3d5

How come we remove one electron from s orbital and one from d oribital? Is it a mistake?

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[Streetwolf]

The d5 configuration is MUCH more stable than the d4 configuration. You're allowed to use one of the 4s electrons in the 3d orbitals. It happens often enough.

 

[Smooth Operater]

thanks street wolf. I think I got tricked.

how about Fe3+

would you remove any electron from 4s ? Or just remove from highest to lowest orbital (i.e. 3d first and 4d) Thanks!

 

[celeron_266]

4s first

it has the highest principle quantum number, and half filled 3d is stable

 

[Smooth Operater]

4s or 3d.

Kaplan books says fill 4s first, but it doesn't matter if we write 4s before or after 3d for writing configuration. So, what 's the RIGHT way to put on DAT exam?

 

[celeron_266]

you dont wanna touch the stable half-filled d subshell, and 4s has a higher principle quantum number, so remove 4s