Compared to the changes in atomic and ionic sizes of elements of 3d and 4d series, the : change in radii of elements of 4d and 5d series is virtually the same Comment.

Explanation

Compared to the change in atomic and ionic sizes of elements 3d and 4d series, the change in radii of elements 4d and 5d series is virtually the same. This is due to the intervention of the 4f orbitals which must be filled before the 5d series of elements begin. The filling of 4f before 5d orbitals results in a regular dectease in atomic radii called lanthanoid contraction. The consequence of lanthanoid contraction is that the 4d and 5d series exhibit same size of radii.