Here's why:

* Atomic Radii: Atomic radius refers to the distance from the nucleus to the outermost electron shell of an atom. Iron has a larger atomic radius than sodium.

* Electron Configuration: Iron has more electrons than sodium. These electrons occupy more energy levels, resulting in a larger atomic size.

* Shielding Effect: The inner electrons in an atom shield the outer electrons from the full attraction of the nucleus. Iron, with more electrons, has a greater shielding effect, which also contributes to a larger atomic radius.

In summary: While both sodium and iron are in the same period (row) on the periodic table, iron is further to the right. This means it has more protons and electrons, leading to a larger atomic size.