Which of the following statements correctly describes the resonance structures of the NO_2^- ion?

• A. NO_2^- has two equivalent resonance structures, each with one oxygen atom double-bonded to nitrogen and the other single-bonded, with a negative charge on the singly bonded oxygen.
• B. NO_2^- has three resonance structures, each with a different atom carrying the negative charge.
• C. NO_2^- has two resonance structures, both with the negative charge on the nitrogen atom.
• D. NO_2^- has only one Lewis structure with both oxygen atoms double-bonded to nitrogen and no formal charges.

Answer: (A)

Verified step by step guidance

1. Recall that resonance structures are different Lewis structures for the same molecule that differ only in the placement of electrons, not atoms.
2. Draw the Lewis structure of the nitrite ion (NO_2^-), counting total valence electrons: nitrogen has 5, each oxygen has 6, and there is one extra electron due to the negative charge, totaling 18 electrons.
3. Arrange the atoms with nitrogen in the center bonded to two oxygen atoms, then distribute electrons to satisfy the octet rule as much as possible.
4. Identify possible resonance structures by moving the double bond between nitrogen and one oxygen to the other oxygen, resulting in two structures where one oxygen is double-bonded and the other is single-bonded with a negative charge.
5. Check the formal charges in each resonance structure to confirm that the negative charge is localized on the singly bonded oxygen atom, and that the two resonance structures are equivalent in energy.