Comment on the statement that elements of the first transition series possess many properties different from those of heavier transition elements.

Explanation

The points given below justify the statement :
(i) Atomic radii of the heavier transition elements (4d and 5d series) are larger than those of the corresponding elements of the first transition series though those of 4d and 5d series are very close to each other.
(ii) Enthalpies of atomisation of 4d and 5d series are higher than the corresponding elements of the first series.
(iii) Melting and boiling points of heavier transition elements are greater than those of the first transition series due to stronger intermetallic bonding.
(iv) For first transition series, +2 and +3 oxidation states are more common whereas for heavier transition elements, higher oxidation states are more common.
(v) Ionisation enthalpies of 5d series are higher than the corresponding elements of 3d and 4d series.