The chemistry of the actinoid elements is not so smooth as that of the lanthanoids. Justify this statement by giving some examples from the oxidation state of these elements.

Explanation

Lanthanoids show limited number of oxidation state, viz., +2, +3 and +4 (out of which +3 is most common). This is because of large energy gap between 4f, 5d and 6s subshells. The dominant oxidation state of actinoids is also +3 but they show a number of other oxidation states also, e.g., uranium (Z = 92) and plutonium (Z = 94) show +3, +4, +5 and +6, neptunium (Z = 94) shows +3, +4, +5 and +7, etc. This is due to small energy difference between 5f, 6d amd 7s subshells of the actionoids. Depending upon the reaction conditions, any number of electrons from 5f, 6d and 7s can participate.