How many unpaired electrons does the element cobalt (Co) have in its lowest energy state?
A) 0
B) 1
C) 2
D) 3
E) 7

Question

Quizplus · Accepted Answer

Cobalt (Co) has an atomic number of 27, which means in its ground state, it has 27 electrons. The electron configuration of Co is [Ar] 3d^7 4s^2. In the 3d subshell, there are 7 electrons. According to Hund's rule, these electrons will fill the five 3d orbitals in such a way that maximizes the number of unpaired electrons. This results in three unpaired electrons in the 3d subshell.

How Many Unpaired Electrons Does the Element Cobalt (Co) Have