Why does the atomic radius increase as you go from the top to the bottom of a chemical family

The atomic radius increase as you go from the top to the bottom of a chemical family

Step-by-step explanation:

The atomic radius is defined as one-half the distance between the nuclei of identical atoms that are bonded together.

The atomic radius of atoms generally increases from top to bottom within a group. As the atomic number increases down a group, there is again an increase in the positive nuclear charge. However, there is also an increase in the number of occupied principle energy levels. Higher principal energy levels consist of orbitals which are larger in size than the orbitals from lower energy levels. The effect of the greater number of principal energy levels outweighs the increase in nuclear charge and so atomic radius increases down a group.