Question

Among the following, the smallest in size is
a) Cl-
b) Nat
c) Mg2+
d) S-​

Answer 1

Answer:

c) Mg2+

Explanation:

The ionic size is smallest for Mg2+. Na+ and Mg2+ contains 2 shells of electrons whereas Cl− and S2− contain 3 shells of electrons. Hence the ionic radii of Na+ and Mg2+ are smaller than the ionic radii of Cl− and S2−. Mg2+ and Na+ are isoelectronic species. The effective nuclear charge of Mg2+ is higher than the effective nuclear charge of Na+. Hence, the ionic radius of Mg2+ is smallest.