How many unpaired electrons are in a chromium trivalent ion?
A) 0
B) 5
C) 6
D) 4
E) 3

Question

Quizplus · Accepted Answer

Chromium (Cr) has an electron configuration of [Ar] 3d5 4s1. When it forms a trivalent ion, it loses three electrons from the 4s and one from the 3d sublevel to become [Ar] 3d3. Each 3d orbital can hold 2 electrons, so there are a total of 6 electrons in the 3d sublevel. However, in a trivalent ion, all of these electrons are paired up, leaving no unpaired electrons. Therefore, the answer is E) 3.

How Many Unpaired Electrons Are in a Chromium Trivalent Ion