Question

In each of the following pairs, choose the atom having the bigger size :

(a) Mg (At. No. 12) or Cl (At. No. 17)

(b) Na (At. No. 11) or K (At. No. 19)

Answer 1

(a) Mg has a bigger size than Cl because the atomic size decreases on moving from left to right in a period of the periodic table. Mg and Cl belong to group 3 of the periodic table.

(b) K has a bigger size than Na because the atomic size increases on going down in a group of the periodic table. Na and K belong to group 1 of the periodic table.