Draw both resonance forms of the nitrite ion (NO2⁻). Be sure to include all lone pairs and non-zero formal charges.

The nitrite ion (NO₂⁻) can be represented by two resonance forms that illustrate its bonding structure and charge distribution.

In the first resonance form, one of the oxygen atoms is double-bonded to the nitrogen atom, while the other oxygen is single-bonded and carries a negative charge:

       O
       ||
       N  --->  O-
       |
       O- 

In this structure, the formal charges can be calculated as follows:

• Nitrogen (N): 5 valence electrons (group number) – 0 non-bonding electrons – 1/2(4 bonding electrons) = +1 formal charge.
• Oxygen with double bond: 6 valence electrons – 4 non-bonding electrons – 1/2(4 bonding electrons) = 0 formal charge.
• Oxygen with single bond: 6 valence electrons – 6 non-bonding electrons – 1/2(2 bonding electrons) = -1 formal charge.

Now for the second resonance form, we simply switch the oxygen atoms’ roles:

        O-
       |
       N  --->  O
       ||
       O

In this second structure, the formal charges are calculated similarly:

• Nitrogen (N): 5 valence electrons – 0 non-bonding electrons – 1/2(4 bonding electrons) = +1 formal charge.
• Oxygen with single bond: 6 valence electrons – 6 non-bonding electrons – 1/2(2 bonding electrons) = -1 formal charge.
• Oxygen with double bond: 6 valence electrons – 4 non-bonding electrons – 1/2(4 bonding electrons) = 0 formal charge.

Both resonance forms contribute to the overall structure of the nitrite ion, and they help us understand the distribution of charge and the equivalent nature of the nitrite ion’s bonding.