Which of thefollowingspecieshas thelargestand thesmallest size ? Mg^(2

1.	Which of thefollowingspecieshas thelargestand thesmallest size ? Mg^(2+) ,Al,Al^(3+)
Answer» Solution :(i) Mgand A1belongto thethirdperiod.Acrossa periodatomicradiidecreasedue toincreases nuclear charge . Thereforeatomicsizeof ALIS smaller thanthat of Mg. (ii)Further cations are smaller thantheir parentatoms. Therefore `Mg^(2+)` si smallerthan Mg and `Al^(3+)` issmallerthan Al. (III) `Mg^(2+)` and `Al^(3+)` are isoelectronicions. AMONG isoelectronicions, higher the + vechargesmallerthesize. Thereforeionicradiusof `Al^(3+)` is smallerthan thatof `Mg^(2+)` Fromthe abovediscussionsit followsthat MGHAS thelargestwhile`Al^(3+)` has thesmallestsize.

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