# What is the electron configuration of the iron iii ion?

Dec 21, 2016

The electron configuration for the iron(III) ion is:

$\text{1s"^2"s"^2"2p"^6"3s"^2"3p"^6"3d"^5}$

#### Explanation:

The element iron, Fe, has the atomic number 26, which is the number of protons in its atomic nuclei. A neutral iron atom has 26 protons and 26 electrons. In order to form a ${3}^{+}$ ion, it must lose three electrons.

The ground state electron configuration for a neutral atom of iron is:

$\text{1s"^2"s"^2"2p"^6"3s"^2"3p"^6"3d"^6"4s"^2}$

The electron configuration for the iron(III) ion is:

$\text{1s"^2"s"^2"2p"^6"3s"^2"3p"^6"3d"^5}$

The Fe atom loses two $\text{4s}$ electrons and one $\text{3d}$ electron.