How would you arrange the following elements from largest to smallest in atomic radii: S, Al, Ar, Mg, P?
There are two factors affecting atomic radii.
First, atomic radius is in correlation with the value n . n represents the energy level, or the shell, of an atomic radius and its relative size. Hence, a larger n value means a larger atomic radii.
In general, atomic radii increases from right to left on a periodic table.