Na, Mg and Al are the elements of the `3^(rd)` period of the Modern Periodic Table having group number 1, 2 and 13 respectively . Which one of these has the (a) highest valency (b) largest atomic radius, and (c ) maximum chemical reactivity? Justify your answer stating the reason for each.

Explanation

(a) Aluminium (Al) metal has highest valency of '3' valence electrons in its outermost shell.
(b) Na atoms have largest atomic radius. As the atomic radius of atoms of the elements of same period go on decreasing as we move from left to right in a period.
(c ) Na metal will show maximum chemical reactivity, as chemical reactivity among the metals goes on decreasing in the same period as we move from left to right in that period.