What is the hybridization of the carbon in HCN? A. sp B. sp C. sp3 D. sp3d
A. sp
B. sp2
C. sp³
D. sp³d
E. sp³d2
The correct answer and explanation is :
Correct Answer: A. sp
Explanation (≈300 words):
To determine the hybridization of the carbon atom in hydrogen cyanide (HCN), we need to analyze the molecule’s structure and bonding.
Step 1: Lewis Structure of HCN
HCN consists of three atoms: hydrogen (H), carbon (C), and nitrogen (N). The correct Lewis structure is:
H–C≡N
- Hydrogen forms one single bond (H–C).
- Carbon forms a single bond with H and a triple bond with N.
- Nitrogen has a lone pair of electrons.
So, the carbon is bonded to two atoms: one hydrogen and one nitrogen. Even though the triple bond with nitrogen includes multiple electron pairs, it still counts as one region of electron density in terms of hybridization.
Step 2: Electron Domain Geometry
Hybridization depends on the number of regions of electron density (bonding domains and lone pairs) around the atom. In this case:
- The carbon has two regions of electron density (H and N).
Thus, carbon in HCN has a linear geometry and requires two hybrid orbitals.
Step 3: Type of Hybridization
- 2 regions of electron density → sp hybridization
- 3 regions → sp²
- 4 regions → sp³
- 5 regions → sp³d
- 6 regions → sp³d²
Therefore, with two regions of electron density, carbon in HCN is sp hybridized.
This hybridization allows the carbon to form:
- One σ bond with hydrogen using an sp orbital.
- One σ bond with nitrogen using the other sp orbital.
- Two π bonds (from the triple bond) are formed from the unhybridized p orbitals on carbon and nitrogen.
Conclusion
The correct hybridization of the carbon atom in HCN is sp, which corresponds to option:
A. sp ✅
