Question

The radii of N, N3–, O and O2– are in the order :

• A. N3–> O2–> O > N
• B. O2–> N3–> N > O2–> O
• C. N3–> O2–> N > O
• D. N > O > O2–> N3–

Answer 1

Answer: (C)

N3–> O2–> N > O

Answer 2

(1) Anion is bigger than parent atom and for isoelectronic species ionic size$\propto$ $\frac{1}{nuclearch\arg e}$. Along the

period atomic size decreases due to increasing nuclear charge.

N = 70 pm ; N3– = 171 pm ; O = 66 pm ; O2– = 140 pm

So, the correct order of radii is N3– > O2– > N > O.