Add Formal Charges to Each Resonance Form of HCNO Below. Based on the Formal Charges You Added Above, Which Structure is Favored?

To evaluate the resonance forms of HCNO (hydroxylamine), we need to first determine the formal charges on each atom in the different resonance structures. The formal charge (FC) can be calculated using the formula:

FC = V – (N + B/2)

• V = number of valence electrons in the free atom
• N = number of non-bonding (lone pair) electrons on the atom
• B = number of bonding electrons (sharing with other atoms)

For HCNO, we consider several resonance forms:

1. Resonance Structure 1: H=N-O
• H: 1 V – 0 N – 0.5 B = 0 (no formal charge)
• N: 5 V – 0 N – 3 B = +1
• O: 6 V – 4 N – 2 B = 0 (no formal charge)
2. Resonance Structure 2: H-O=N
• H: 1 V – 0 N – 0.5 B = 0 (no formal charge)
• O: 6 V – 2 N – 2 B = +1
• N: 5 V – 2 N – 2 B = +1
3. Resonance Structure 3: N#C-OH
• N: 5 V – 0 N – 4 B = +1
• C: 4 V – 0 N – 4 B = 0 (no formal charge)
• O: 6 V – 2 N – 2 B = 0 (no formal charge)

Now, we analyze the formal charges:

• The first structure has a total FC of +1.
• The second structure has a total FC of +2.
• The third structure has a total FC of +1.

When assessing which structure is favored, we prefer the resonance form with the least number of formal charges or the most stable arrangement. The first and third structures, with a total FC of +1, keep charges lower compared to the second structure which has a total of +2. Thus, we can conclude:

Conclusion: The first and third resonance forms are both favored due to their lower formal charges, with the first structure being particularly stable as it contains fewer formal charges distributed over the atoms.