Compare the chemistry of actinoids with that of the lanthanoids with special reference to:

Explanation

(i). Electronic configuration: The general electron configuration of lanthanoids is `4f^(1-14)4d^(0-1)` `6s^2` whereas that of actinoids is `5f^(1-14)6d^(0-1)6s^2` whereas that of actinoids is `5f^(1-14)6d^(0-1)7s^2`. Thus lanthanoids belong to 4f-series whereas actinoids belong to 5f-series.
(ii). Oxidation states: Lanthanoids show limited oxidation states `(+2,+3,+4)` out of which `+3` is most common. This is because of large energy gap between 4f,5d and 6s subshells. On the other hand, actinoids show a large number of oxidation states because of small energy gap between 5f, 6d and 7s subshells.
(iii). Atomic and ionic sizes: Both show decrease in size of their atoms or ions in `+3` oxidation state. In lanthanoids, the decrease is called lanthanoid contraction whereas in actinoids, it is called actinoid contraction. However, the contraction is greater from element to element in actinoids due to imperfect shieldintg by 5f electrons.
(iv). Chemical Reactivity: Refer to section 6.12.