Desrible the variable oxidation state of 3d series elements .

Explanation

(i)The first transition metal scandium exhibits only +3 oxidatin state but all other transition elements exhibit variable oxidation states by loosing electrons from (n-1) orbital and ns orbital as the energy difference between them is very small.
(ii) At the beginning of the series +3 oxidation state is stable but toward the end +2 oxidation state becomes stable.
(iii) The number of oxidation states increases with the number of electrons available and it decreases as the number of paired electrons increases . Hence the first and last elements show less number of oxidation states and the middle elements with more number of oxidation states.