Question

question 14 (5 points)
listen
hydrogen cyanide has the chemical formula hcn. whats the formal charge on the n atom?
a) -2
b) +2
c) -1
d) 0

Explanation:

Step1: Recall formal charge formula

The formula for formal charge (FC) is \( FC = V - N - \frac{B}{2} \), where \( V \) is the number of valence electrons in the neutral atom, \( N \) is the number of non - bonding (lone pair) electrons, and \( B \) is the number of bonding electrons.

For nitrogen (\( N \)): The number of valence electrons in a neutral \( N \) atom, \( V = 5 \).

In the HCN molecule, the Lewis structure of HCN is \( H - C\equiv N \). For the \( N \) atom in \( H - C\equiv N \):

• The number of non - bonding electrons (\( N \)): In a triple bond between \( C \) and \( N \), the \( N \) atom has 1 lone pair (2 non - bonding electrons), so \( N = 2 \).
• The number of bonding electrons (\( B \)): In a triple bond, there are 6 bonding electrons, so \( B = 6 \).

Step2: Calculate formal charge

Substitute the values into the formal charge formula:
\( FC=5 - 2-\frac{6}{2} \)
First, calculate \( \frac{6}{2}=3 \). Then, \( 5 - 2-3=0 \).

Answer:

D) 0