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.

Among the actinoids, there is a greater range of oxidation states as compared to lanthanoids. This is in part due to the fact that 5f, 6d and 7s levels are of very much comparable energies and the frequent electronic transition among these three levels is possible. This 6d-5f transition and larger number of oxidation states among actinoids make their chemistry more complicated particularly among the 3rd to 7th elements. Following examples of oxidation states of actinoids. Justify the complex nature of their chemistry.

(i) Uranium exhibits oxidation states of+3, +4, +5, +6 in its compounds. However, the dominant oxidation state in actinoides is +3.

(ii) Nobelium, No is stable in +2 state because of completely filled f¹⁴ orbitals in this state.

(iii) Berkelium, BK in +4 oxidation state is more stable due to f⁷ (exactly half filled) configuration.

(iv) Higher oxidation states are exhibited in oxo ions are UO₂²⁺, PuO₂²⁺, NpO⁺ etc.