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

Answer

The given statement is true as explained below:
(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 through of `(4d and 5d series)` are very close to each other.
(ii) For first transition series,+2 anxd +3` oxidation state are more common whereas for heavier transition elements, higher oxidation state are more common.
`(iii) Melting and boiling points of heavier elements are greater than those of the first transition series due to strong intermettalic bonding (M-M bonding).
(iv) Enthalpies of atomisation of `4d` and `5d` series are higher than the corresponding element of the first series.
(V) lonisation enthalpies of `5d` series are higher than the corresponding elements of `3d` and `4d` series.
`(Vi)` The elements of the first transition series from low spin or high spin complex depending upon the strength of the ligand field . However, the heavier element from low spin complex irrespective of the strength of the ligand field.