[semistry]

hello all,

What is the number of unpaired electrons in an isolated free ion atom in the ground state?

I got 2 is that right? It's element #26 by the way.

[Donaldson Tan]

the ground state electronic configuration of the iron atom is  [Ar].3d6.4s2

from the configuration, you can tell that only the 3d subshell is not completely filled. The 3d subshell holds a maximum of 10electrons. It consist of 5 orbitals. By Pauli's Exclusion Principle for the electron, the 6 3d electrons occupy the 5 orbitals in the following arrangement: 1 full orbital and 4 half-filled orbitals.

In another words, there are 4 unpaired electron in ground state iron atom.