I) How does the atomic radius change as you go a) From left to right in a period?
b) Down a group in the periodic table?

In general, the atomic radius decreases as we move from left to right in a period and it increases when we go down a group. This is because in periods the valence electrons are in the same outermost shell. The atomic number increases within the same period while moving from left to right which in turn increases the effective nuclear charge.

Explanation: