What happens to the atomic radius as you go across a row from lithium to neon?

It decreases

Explanation:

As one moves from lithium to neon across the periodic table, the atomic radius reduces drastically.

Atomic radius is half of the internuclear distance between two covalently bonded atoms of a non-metallic element. It is also half of the distance between two nuclei in the solid state of metals. Therefore, across the period it reduces due to increase in the nuclear charge without any attendant increase in the number of electronic shells. Consequently, the electrons are pulled more tightly around the nucleus