Justify the followijng statement .
" Elements of the first transition series posses many properties different from those of heavier transition elements "

Explanation

The heavier transition elements belong to fourth (4d ) , fifth (5d ) and sixth (6d) transition series.
Their properties are expected to be different form the elements belonging to the first (3d) series due to following reasons.
(i) atomic : radii : Size of the transition those of the corresponding element of the first transition series though those of 4d and 4d series are very close to each other.
(ii) Ionisation enthalpy of 5d series are higher than the corresponding element of 3d and 4d series .
(iii) A tomisation higher than the corresponding elements of teh first series.
(iv) the element of the first transition series generally form low or high spin complexes. depending upon hte higher of ligand filed.
However the heavier transition elements form low spin complexes irrespective of the strength of ligand filed.