Which of the following Lewis structures for the nitrate ion (NO_3^-) is most stable based on formal charges?

• A. A structure where all atoms have a formal charge of 0.
• B. A structure where the central nitrogen has a formal charge of -1 and all oxygens have formal charges of 0.
• C. A structure where the central nitrogen has a formal charge of +1 and one oxygen has a formal charge of -1, with the other two oxygens having formal charges of 0.
• D. A structure where the central nitrogen has a formal charge of 0 and all three oxygens have formal charges of -1.

Answer: (C)

Verified step by step guidance

1. Recall that the stability of Lewis structures is often determined by minimizing formal charges and placing negative formal charges on the more electronegative atoms.
2. Calculate the formal charge for each atom using the formula: \(\text{Formal Charge} = \text{Valence Electrons} - (\text{Nonbonding Electrons} + \frac{1}{2} \times \text{Bonding Electrons})\).
3. For the nitrate ion (NO\(_3^-\)), assign electrons to nitrogen and oxygen atoms in each proposed structure and compute their formal charges accordingly.
4. Compare the formal charges in each structure: the most stable Lewis structure typically has formal charges closest to zero, with negative charges on oxygen (more electronegative) rather than nitrogen.
5. Identify the structure where nitrogen has a formal charge of +1, one oxygen has a formal charge of -1, and the other two oxygens have formal charges of 0, as this arrangement minimizes formal charges and places the negative charge on oxygen, making it the most stable.