what happens to the radius of the atoms of an element as you go down a column of the periodic table ?

Increases

Explanation:

The atomic radius increases as you go down a periodic table. Across a period which is a row, the atomic radius reduces.

The atomic radius is taken as the half of the inter-nuclear distance between two covalently boned atoms of non-metallic elements. It is also, half of the distance between two nuclei in the solid state. Across a period in the periodic table, atomic radii decreases progressively from left to right. Down a group it increases from up down.