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Justify thepositionof lanthanidesand actinidesin theperiodic table . |
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Answer» Solution :(i) Theactualpositionof Lanthanoidsin theperiodictableis atgroupnumber 3and periodnumber6 .Howeverin the sixthperiodafterlanthanum , theelectrons arepreferentiallyfilledin inner4fsubshellandthesefourteenelements followinglanthanumshowsimilarchemicalproperties.Therefore THESEELEMENTS are groupedtogether andplacedat thebottomof theperiodictable . Thispositioncan bejustifiedas follows. (a)Lanthanoids have generalelectronicconfiguratration`[Xe] 4f^(gamma -14) 5D^(0-1) 6s^(2)` ( b)The commonoxidationstateoflanthanoides is +3 ( C )All theseelementshave similar(ii) Simiilarlythe fourtheenelementsfollowingactiniumresemble in theirphysicaland CHEMICALPROPERTIES . (iii)Similarto lanthanoids activitiesare alsoplacedin a separaterowat the bottonof theperiodictable. |
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