Question

Oxidation number according electronic configuration

Answer 1

Suppose I know that Selenium has electron configuration [Ar]4s23d104p4.

How can I use this information to then come to the conclusion that its possible oxidation states are 6, 4, 2, 1 and -2?

I understand the 6: Give up all s electrons to reach Ar configuration I also understand the -2: Obtian two electrons to complete the 4th shell. I can guess why 4 is plausible: Give up all your 4p electrons