The question is:
Which of the following possesses the highest energy electron?
My attempt at the problem:
Br- has its last electron in the 4p6, which is [Ar]
Ca2+ has its last electron in the 3p6 level
Cr+ has its last electron in the 3d5 level, because regular Cr has electron config of [Ar]3d5 4s1
As has its last electron in the 4p3 level.
I answered C. But the book's answer is D. But I don't understand why because I thought by energy level from lowest to highest goes by this:
1s2 2s2 2p6, 3s2 3p6 4s2 4p6 3d10, which d has a higher energy level than p. Additionally, going by the book, As has its electron at the 4p3 suborbital
whereas, A has its electron at the 4p6 which is higher than 4p3. Please help me. Thank you!