Question

The ionic radii of F^- and Na⁺ are 133 and 98 pm, respectively.

Answer 1

• F^- and Na⁺ are isoelectronic ions as they both have 10 electrons.
• However, the nuclear charge on F^- is +9 while that of Na⁺ is +11.
• In isoelectronic species, larger nuclear charge exerts greater attraction on the electrons and thus, the radius of that isoelectronic species becomes smaller.

Thus,

F^- has larger ionic radii (133 pm) than Na⁺ (98 pm).