Question

Why is the atomic radius of Cs larger than Fr ?

Answer 1

Down the group atomic radius increases..so Cs has larger atomic radius of all

Answer 2

Answer:

As after Cs D and F Block {lanthanides} are introduced which increases the nuclear charge of Fr to a great extent and due to poor shielding effect of D and F orbitals the effective nuclear charge on the outermost electron increases which results in the contraction of electron cloud of Fr and hence decreases the atomic size of Fr.