Give examples and suggest reason for the following features of the transition metals Chemistry.
(ii). A transition metal exhibits highest oxidation state in oxides and fluorides.
(iii). The highest oxidation state is exhibited in oxoanions of a metal.

Explanation

(a) It may be noted that in the different oxides of the same element, the acidic strength increasing with the increase in oxidation state of the element. MnO `(Mn^(2+))` is basic while `Mn_(2)O_(7)(Mn^(7+))` is acidic in nature.
(b) Both oxygen and fluorine being highly electronegative can increase the oxidation state of a particular transition metal. In certain oxides, the element oxygen is involved in multiple bonding with the metal and this is responsible for the higher oxidation state of the meal.
(c) This is also because of the high electronegativity of oxygen. For example, chromium exhibits oxidation state of (VI) in oxoanion `[Cr(VI)O_(4)]^(2-)` and manganese shows oxidation state of (VII) in oxoanion `[Mn(VII)O_(4)]^(-)`.