Which of the following correctly represents the Lewis dot structure for the nitrite ion, NO_2^-?

• A. The ion has two resonance structures, each with one N–O triple bond and one N–O single bond.
• B. The ion has a single structure with two N–O single bonds and two lone pairs on nitrogen.
• C. The ion has two resonance structures, each with one N–O single bond and one N=O double bond, and a lone pair on nitrogen.
• D. The ion has a single structure with two N–O double bonds and no lone pairs on nitrogen.

Answer: (C)

Verified step by step guidance

1. Step 1: Determine the total number of valence electrons for the nitrite ion (NO_2^-). Nitrogen has 5 valence electrons, each oxygen has 6, and the negative charge adds 1 extra electron. So, total electrons = 5 + 2×6 + 1 = 18 electrons.
2. Step 2: Draw a skeletal structure with nitrogen as the central atom bonded to two oxygen atoms. Connect nitrogen to each oxygen with single bonds initially.
3. Step 3: Distribute the remaining electrons to satisfy the octet rule for the oxygen atoms first, placing lone pairs around them to complete their octets.
4. Step 4: Check the octet of nitrogen. If nitrogen does not have a full octet, form double bonds by converting lone pairs from oxygen into bonding pairs between nitrogen and oxygen. This leads to resonance structures where one N–O bond is a double bond and the other is a single bond.
5. Step 5: Add a lone pair to nitrogen to complete its octet and place brackets around the structure with the negative charge indicated. Recognize that the actual structure is a resonance hybrid of two such resonance forms.