Question

below is a resonance structure for ch₃no. label the formal charges on the selected atoms.

Explanation:

Step1: Recall formal - charge formula

The formula for formal charge 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 oxygen

Oxygen has 6 valence electrons ($V = 6$). In the given structure, it has 6 non - bonding electrons ($N = 6$) and 2 bonding electrons ($B = 2$).
$FC_O=6 - 6-\frac{2}{2}=6 - 6 - 1=- 1$

Step3: Calculate formal charge of carbon

Carbon has 4 valence electrons ($V = 4$). It has 0 non - bonding electrons ($N = 0$) and 8 bonding electrons ($B = 8$).
$FC_C=4 - 0-\frac{8}{2}=4 - 4 = 0$

Step4: Calculate formal charge of nitrogen

Nitrogen has 5 valence electrons ($V = 5$). It has 0 non - bonding electrons ($N = 0$) and 8 bonding electrons ($B = 8$).
$FC_N=5 - 0-\frac{8}{2}=5 - 4 = + 1$

Answer:

Oxygen: B. - 1
Carbon: C. 0
Nitrogen: D. + 1