Question

F, Cl and Br are the elements each having seven valence electrons. Which of these (i) has the largest atomic radius, (ii) is most reactive? Justify your answer, stating the reason for each.

Answer 1

(i) F, Cl and Br belong to the same group, 17. Atomic size increases down the group. This is because new shells are added. Hence, Br has the largest atomic radius because it has more shells compared to 3 and 2 in Cl and F respectively.

(ii) F is most reactive due to its smaller size, high effective nuclear charge and high electronegativity.