Which of the following species will have the largest and the smallest size `Mg, Mg^(2+), Al, Al^(3+)`?

Options

A. `Mg, A1^(3+)`
B. `A1^(3+) ,Mg`
C. `Mg^(2+) , A1`
D. `A1,Mg^(2+)`

Answer

A

Explanation

Along a period atomic radii decrease .Therefore Mg has smaller atomic radius thant A1.
Amongst isoelectronic ions (i.e., `Mg^(2+) =12-2=10` electronic and `A1^(3+) =13- 3 =10 ` electrons ) , higher the + Ve charge smaller the ionic radius Thus `A1^(3+)` has smaller ionic radius than `Mg^(2+)`
Combining the two trends Mg has the largest adn `A1^(3+)` has the smallest size i.e., option (a) is correct.