What happens to the atomic radius as you move down a group in the periodic table?

As you move down a group in the periodic table, the atomic radius increases. This increase is primarily due to the addition of electron shells. Each element in a group has the same number of valence electrons but resides in a higher principal energy level as you progress down the group.

As more electron shells are added, the distance between the nucleus and the outermost electrons increases, resulting in a larger atomic size. Additionally, while there is an increasing positive charge in the nucleus, the effect of increased electron shielding (due to the inner electrons repelling the outer electrons) also plays a significant role in allowing the atomic radius to expand. This combination of added shells and electron shielding leads to a noticeable increase in atomic radius as you descend a group.