Transcript text: Draw the Lewis structure for HCN.
Solution
Solution Steps
Step 1: Determine the Total Number of Valence Electrons
Hydrogen (H) has 1 valence electron, carbon (C) has 4 valence electrons, and nitrogen (N) has 5 valence electrons. Therefore, the total number of valence electrons in HCN is:
\[ 1 + 4 + 5 = 10 \]
Step 2: Arrange the Atoms
The least electronegative atom (excluding hydrogen) is typically placed in the center. In HCN, carbon is the central atom, with hydrogen and nitrogen on either side:
\[ \text{H} - \text{C} - \text{N} \]
Step 3: Form Single Bonds
Connect the atoms with single bonds. Each single bond represents 2 electrons:
\[ \text{H} - \text{C} - \text{N} \]
This uses 4 electrons (2 for each bond).
Step 4: Distribute Remaining Electrons
Distribute the remaining 6 electrons to satisfy the octet rule for each atom (except hydrogen, which only needs 2 electrons):
Carbon has 2 electrons from each bond (4 total) and needs 4 more.
Nitrogen has 2 electrons from the bond with carbon and needs 6 more.
Step 5: Form Multiple Bonds if Necessary
To satisfy the octet rule for carbon and nitrogen, form a triple bond between carbon and nitrogen:
\[ \text{H} - \text{C} \equiv \text{N} \]
This uses all 10 electrons (2 for the H-C bond and 6 for the C≡N bond).
Final Answer
The Lewis structure for HCN is:
\[ \boxed{\text{H} - \text{C} \equiv \text{N}} \]