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Compare the chemistry of actinoids with that of the lanthanoids with special reference to: (i) Electronic configuration (ii) Atomic and ionic sizes (iii) Oxidation state (iv) Chemical reactivity |
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Answer» Solution :(i) Electronic configuration: Lanthanoids have general electronic configuration `[Xe] 4f^(1-14) 5d^(0-1) 7s^(2)` and actionoids have general electronic configuration of `[RN] 5f^(1-14) 6f^(0-1) 7s^(2)`. (ii) Atomic and ionic sizes: From, lanthanum to leutetium, atomic size DECREASES though decrease is not regular. However, decrease in size of `M^(3+)` ions is very sharp. In case of actinoids, the decrease in size is more pronounced from elements to element because of poor sheilding effect of 5f electrons. (iii) OXIDATION states: The most common oxidation state in lanthanoid is (+3). However, (+2) and (+4) oxidation states are also shown by lanthanoids. The actinoid shows variable oxidation states ranging from (+3) to (+7). This is because of comparable energies of 5f, 6d and 7s levels. (iv) Chemical REACTIVITY: As compared to lanthanoids, actinoids are more reactive. At moderate temperatures, actionoids REACT with non-metals while at lanthanoid reacts at high temperature. Actinoids are not attacked by `HNO_(3)` because of formation of protective layer of oxides on its surfae and also they are not attacked by alkali. However, actinoids react with HCl. Lanthanoids liberates `H_(2(g))` from dilute acids and produces trihalides when reacted with halogens. |
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