Question

below is a resonance structure for no₃⁻. label the formal charges on the selected atoms.

Explanation:

Step1: Recall formal - charge formula

The formal - charge formula is $FC = V - N - \frac{B}{2}$, where $V$ is the number of valence electrons, $N$ is the number of non - bonding electrons, and $B$ is the number of bonding electrons.

Step2: Calculate formal charge of nitrogen

Nitrogen has 5 valence electrons ($V = 5$). In the $NO_3^-$ structure, it has 0 non - bonding electrons ($N = 0$) and 8 bonding electrons ($B = 8$). Using the formula $FC_N=5 - 0-\frac{8}{2}=+ 1$.

Step3: Calculate formal charge of double - bonded oxygen

Oxygen has 6 valence electrons ($V = 6$). The double - bonded oxygen has 4 non - bonding electrons ($N = 4$) and 4 bonding electrons ($B = 4$). Using the formula $FC_{O_{double}}=6 - 4-\frac{4}{2}=0$.

Step4: Calculate formal charge of single - bonded oxygen

Oxygen has 6 valence electrons ($V = 6$). A single - bonded oxygen has 6 non - bonding electrons ($N = 6$) and 2 bonding electrons ($B = 2$). Using the formula $FC_{O_{single}}=6 - 6-\frac{2}{2}=-1$.

Answer:

Nitrogen: D. +1; Double - bonded oxygen: C. 0; Single - bonded oxygen: B. -1