Describe the change in the atomic radii for the elements in period 2 from lithium to neon

Group 2 doesn't go from Lithium to Neon. It goes (Hydrogen), Lithium, Sodium, Potassium, Rubidium, Cesium, Francium. But, I guess that's not what you're trying to say. In any case, The atomic radius increases going down a group in the periodic table (in general)

If you're talking about a row across the period table (I guess that's what a period is), it's a bit more complicated. In general, the shell gets filled and it gets smaller to Fluorine, but Neon is much larger -- probably as large as Lithium or larger. See here:

http://www.camsoft.co.kr/CrystalMaker/support/tutorials/crystalmaker/resources/VFI_Atomic_Radii_sm.jpg

Group 2 doesn't go from Lithium to Neon. It goes (Hydrogen), Lithium, Sodium, Potassium, Rubidium, Cesium, Francium.

A group is down, but the OP is asking about period 2, periods go across the table.