Question

Which of the following gives the correct increasing order of atomic radii of O, F, and N?

• A. O, F, N
• B. N, F, O
• C. O, N, F
• D. F, O, N

Answer 1

The correct option is D

F, O, N

An explanation for the correct option:

1. There are 7 horizontal rows in the periodic table known as periods. and there is an increase in atomic number as we move across the period from left to right which means the number of protons increases.
2. For a particular period, the number of electronic shells remain same and the valence electrons are added in the same shell.
3. This results an increase in effective nuclear charge i.e. pull, exerted by the nucleus of the atom on the outermost electrons, so across period from left to right atomic size, decreases.
4. Now Nitrogen $\left(N\right)$, Oxygen $\left(O\right)$, and Fluorine $\left(F\right)$ belong to the same period 2. and atomic numbers $\left(Z\right)$ are 7, 8, and 9 respectively.
5. This means that F<O<N, i.e. Fluorine is the smallest and N is the largest among these three.

The correct option is (D) F, O, N and option (A), (B) and (C) are incorrect.