The radii of Fe\(^{2+}\) and Fe\(^{3+}\) ions differ due to the changes in their electronic configurations and the effective nuclear charge experienced by the electrons.
### Electronic Structures:
- **Fe (Iron) atomic number = 26**: The ground state electron configuration of neutral iron (Fe) is \( [\text{Ar}] 3d^6 4s^2 \).
- **Fe\(^{2+}\)**: When iron loses two electrons to become Fe\(^{2+}\), it loses the two 4s electrons. Thus, the electronic


