Comment on the statement that elements of the first transition series possess many properties different from those of heavier transition elements.
Answers
The properties of elements of 1st transition series are different from the heavier transitional elements in several ways.
The atomic sizes of various elements of 1st transition series are smaller than the heavier elements (2nd and 3rd transition series elements).
The +3 and +2 oxidation states are the common for the elements in the 1st transition series.
The heavier transition elements belong to fourth {4d), fifth (5d) and sixth {6d) transition series. Their properties are expected to be different from the elements belonging to the first (3d) series due to the following reasons:
(i) Atomic radii of 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) Ionisation enthalpies of 5d-series are higher than the corresponding elements of 3d and 4d-series.
(iii) Enthalpies of atomisation of 4d-and 5d-series are higher than the corresponding elements of the first series.