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Arrangethe followingionsin orderof theirincreasingionicradii : Li^(+)Mg^(2+) + , K^(+) , A1^(3+) |
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Answer» Solution :(i) Theionicradiusof anycationincreasesas the numberof energyshellsincreasesand decreasesas themagnitudeof thepositivechargeincreases. (ii)`Mg^(2+) ( 1s^(2)2s^(2)2P^(6))` and `A1^(3+)(1s^(2) 2s^(2)2p^(6))` areisoelectronicions andeach ONEOF thesehas twoenergyshells.Since`K^(+) (1s^(2)2s^(2)2p^(6)3s^(2)3p^(6))` has threeshellsand `Mg^(2+) ` and `A1^(2+)` and `A1^(3+)` have twoshellseach, thereforeionicradiusof `K^(+)` is thelargestfollowedby `Mg^(2+) ` and then `A1^(3+)` (IV)Now `Li^(+)(1s^(2))` has oneshell and + 1 chargebut `A1^(3+)(1s^(2)2s^(2)2p^(6))` has twoshell sand + 3charge. Sincethe increasesin the ionicradiusof `A1^(3+)` due tothe PRESENCEOF twoshellsis morethancounterbalanced bythe decrease in itssize dut toan increases in chargefrom + 1 in `Li^(+)` to3 in `A1^(3+)` thereforethe ionicradiusof `A1^(3+)` is lowerthan thatof `Li^(+)` Thusthe ionicradii of thefourionsincreases in theorder : `A1^(3+) lt Li^(+)lt Mg^(2+)lt K^(+)` |
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