question_answer

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

Answer:

Sodium             (Na),     At. number 11,    2, 8, 1

Magnesium   (Mg),     At. number 12,    2, 8, 2

Aluminium     (Al),       At. number 13,    2, 8, 3

(a) The element having the highest valency is Al, as it has 3 valence electrons.

(b) The element with the largest atomic radius is Na as left to right atomic radius decreases.

(c) The element with maximum chemical reactivity is Na as metallic character decreases left to right.