What is the electron configuration for the ion Fe²⁺?

The electron configuration for the ion Fe²⁺ can be understood by first determining the ground state electron configuration of neutral iron (Fe), which has an atomic number of 26. The distribution of electrons in a neutral iron atom is written as [Ar] 4s² 3d⁶. This indicates that after having filled the argon core, there are two electrons in the 4s subshell and six electrons in the 3d subshell.

When iron loses two electrons to form the Fe²⁺ ion, it typically loses the two 4s electrons first, as these are at a higher energy level compared to the 3d electrons. Therefore, the removal of the two electrons results in the configuration [Ar] 3d⁶.

Consequently, the electron configuration for Fe²⁺ is [Ar] 3d⁶, indicating it has retained all six electrons in the 3d subshell while losing the two 4s electrons. This accurately reflects the charge of the ion and provides a stable arrangement of electrons in the 3d subshell.