# Which electrons will be taken when oxidations take place and how does the resulting orbital diagram look like?

In detail, what I really mean is which electron in which orbital is being taken when a oxidation happen? Let me give a example: chromate ion(II)

Two electrons are taken but from which orbital:

• The highest one Commented Nov 20, 2014 at 0:37
• There is no trivial way to predict the resulting configuration with 100% accuracy. Here's a related past answer of mine with a useful link, and a related question. Commented Nov 20, 2014 at 2:33
• Why dissenter?????? Commented Nov 20, 2014 at 22:07
• Which of the electrons in or orbital 3d will be taken? Commented Nov 20, 2014 at 22:07

For iron, which is $\mathrm{[Ar]3d^6 4s^2}$, the higher energy electrons are $\mathrm{4s^2}$, and those that will be removed on oxidation, leading to a $\mathrm{d^6}$ configuration for iron (II).
• For the first transition row, the ion configuration can be predicted. Sorry, I forgot to answer to your example. Cr is $\mathrm{[Ar]3d^54s^1}$, the first eletron to be taken away will be the higher in energy one, ie, the only s electron. Then you have to eliminate another one, and you only have d electrons left, so the $\ce{Cr^2+}$ configuration will be $\mathrm{[Ar]3d^4}$. And yes, many transition metals of the 2nd and 3rd rows, will require you to look them up. Commented Nov 22, 2014 at 18:39