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. In the periodic table, there are 7 horizontal rows known as Periods.
2. There is an increase in atomic number as we move across the period, which means the number of protons increases.
3. In a particular period, the number of electronic shells is the same and the valence electrons are added in the same shell, there is an increase in effective nuclear charge i.e. pull, exerted by the nucleus of the atom on the outermost electrons, so across the period the size of the atom i.e. distance from the center of the nucleus to the outermost shell, decreases.
4. Now Nitrogen (N), Oxygen (O), and Fluorine (F) belong to the same period 2. And atomic numbers (Z) 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.