Compare the general characteristics of the first series of the transition metals with those of the second and third series metals in the respective vertical columns. Give special emphasis on the following points: (i) electronc configurations (ii) oxidation states (iii) ionisation enthalpies (iv) atomic sizes.

Compare the general characteristics of the first series of the transit

1.	Compare the general characteristics of the first series of the transition metals with those of the second and third series metals in the respective vertical columns. Give special emphasis on the following points: (i) electronc configurations (ii) oxidation states (iii) ionisation enthalpies (iv) atomic sizes.
Answer» Solution :(i) Electronic configuration: The 3D, 4D and 5d orbitals are successively filled in `1^(st) and 2^(nd) and 3^(rd)` transition series respectively. (II) Oxidation states: The elements present in the same group, show similar oxidation states. The highest oxidation state is equal to total number of ELECTRONS in d-orbitals and s-orbital. The elements present in the middle of the series show maximum oxidation states. Ex Mn(VII), Os(VIII) etc. The stability of elements in their highest oxidation state increases down the group Ex: W(VI) is move stable than Cr(VI). In first transition series, (+2) and (+3) oxidation states are common. (iii) Ionization enthalpies: Ionization enthalpies in each series increases moving left to right. However, ionization enthalpies of 5d series are nearly same as 4d series due to lanthanoid contraction. (iv) Atomic sizes: The atomic sizes of 4d and 5d series are nearly same due to lanthanoid contraction. The atomic radii increases from 3d to 4d and remains nearly same from 4d to 5d.