Question

how should the atomic size very in period amd groups

Answer 1

atomic size goes on decreasing while going left to right in period
atomic size goes on decreasing while going down a group

Answer 2

Along the period the atomic radius decreases as we go from left to right in the periodic table as no new orbitals are added but the nuclear effective force increases so the size of atom decreases.

Along the group as we move top to bottom in the group size of atom increases as new orbitals are added which increases the size of atom.



hope it helps u ^-^