question_answer 20)

What are the different oxidation states exhibited by the lanthanoids?

Answer:

The main oxidation state of lanthanoids is +3 which is exhibited by all lanthanoids. In addition, some elements also exhibit +2 and +4 oxidation states. However, +3 oxidation state is more stable than +2 and +4 in aqueous solution and in their compounds. La, Gd and Lu have only +3 stable oxidation state because by losing 3 electrons they will get stable empty (4f0),half filled (4f7) and fully filled (4f14) configuration respectively. Ce and Tb show +4 as stable oxidation state because by losing 4 electrons, these will get stable empty (4f0) and half filled (4f7) configuration respectively i.e. Ce4+ = 4f0 and Tb4+ = 4f7. Eu and Yb show stable +2 oxidation state because by losing two electrons these will get stable half filled (4f7) and fully filled (4f14) configuration i.e. Eu+2 = 4f7 and Yb2+ = 4f14.