Question

$1)$ Give examples and suggest reasons for the following features of the transition metal chemistry:
$A)$ The lowest oxide of transition metal is basic, the highest is amphoteric/acidic.

$B)$ A transition metal exhibits highest oxidation state in oxides and fluorides.

$C)$ The highest oxidation state is exhibited in oxoanions of a metal.

Answer 1

$A)$ The transition metals in their lowest oxidation states are basic because some of their valence electrons do not participate in bonding. But they have free electrons which they can donate and act as a base. In the higher oxide of transition metals, most of the valence electrons have already participated in bonding, so they are unavailable. But they can accept electrons and behave as an acid. For example, $MnO(+2)$ behave as a base and $M{n}_2{O}_7(+7)$ behave as an acid.

$B)$ Oxygen and fluorine act as strong oxidising agents because of their high electronegativities and small sizes. Hence, they bring out the highest oxidation states from the transition metals.

In other words, a transition metal exhibits higher oxidation states in oxides and fluorides.

For example, in $Os{F}_6$ and $V_2{O}_5,$
the oxidation states of $Os$ and $V$ are $+6$
and $+5,$ respectively.

$C)$ Oxygen is a strong oxidizing agent because of its small size, high electronegativity and ability to form multiple bonds with elements. Thus oxo-anions of metals shows the highest oxidation state.

For example : In$KMn{O}_4,$ manganese shows $+7$ oxidation state.