how could I arrange the order correct of given elements, when ionic, atomic raddii of different elements is givven which belongs to same group, different periods and different grouPs.?? explain with some examples.

Dear Student,

Atomic radii increases on going from top to bottom in a group and decreases on going left to right across a period.
Ionic radii of cations decreases with increasing charge while ionic radii of anions increases with increasing charge. Within a group, same trend will be followed, i.e. ionic radii will increase on going from top to bottom.
For eg. in group 1 elements, increasing order of atomic radius is
Li < Na < K < Rb < Cs
Increasing order of ionic radii is
Li⁺ < Na⁺ < K⁺ < Rb⁺ < Cs⁺
Within a period, charge will be considered. Greater the charge, smaller the ionic radii.
Therefore, Na⁺ > Mg²⁺ > Al³⁺