(a) Describe the general trends in the following properties of the first series of the transition elements:
(i) Stability of `+2` oxidation state (ii) Formation of oxometal ions
(b) Assign reason for each of the following:
(i) Transition elements exhibit variable oxidation states.
(ii)Transition metal ions are usually coloured

Answer

`(##RES_INO_CHM_V01_XII_V02_C01_S01_312_A01##)`
It is evident from the above table that the maximum number of oxidation state is shown by `Mn`, varying from `+2 to +7`. The number of the oxidation stats increase on moving from Sc to Mn. On moving form `Mn` to Zn , the number of the oxidation state decrease due to a decrease in the number of available unpaired electrons. The relative stability of the `62` oxidation state increase on moving from top to bottom . This is because on moving from top to bottom , it becomes more and more difficult to remove the third electron from the d-orbital. (ii) the element of the first series of transition metals from a variety of oxides of different oxidation state having general formulae `MO,M_(2)O,M_(3)O_(6),MO_(33)`, etc . All metal Sc from `MO` oxides which are ionic in nature . Beyond group 7, no higher oxides excepts `Fe_(2)O_(3)` are known . THe oxocations stabilise as `VO_(2)^(+)` VO_(2)^(+)` and `TiO^(2+)`.