Write the electron configuration (s, p, etc) for an iron atom. - Leaving Cert Chemistry - Question c - 2018

The atomic number of iron (Fe) is 26, indicating that it has 26 electrons. The electron configuration follows the Aufbau principle, filling the lowest energy orbitals first. Thus, the electron configuration for an iron atom is:

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁶

Alternatively, using the noble gas shorthand, this can also be expressed as:

[Ar] 4s² 3d⁶

This representation shows that after the electron configuration of argon ([Ar]), there are 2 electrons in the 4s subshell and 6 electrons in the 3d subshell.