Determine the hybridization about carbon in H2CO.
a) sp
b) sp2
c) sp3
d) sp3d
The Correct Answer and Explanation is :
The correct answer is b) sp2.
Explanation:
In formaldehyde (H₂CO), the central carbon atom is bonded to two hydrogen atoms and one oxygen atom (via a double bond). To determine the hybridization of the carbon atom in H₂CO, we need to look at its bonding and the electron geometry.
- Electron Domains:
The carbon atom in H₂CO is bonded to three atoms: two hydrogens and one oxygen. The carbon forms:
- A single bond with each hydrogen atom (two sigma bonds).
- A double bond with oxygen, which consists of one sigma bond and one pi bond.
Therefore, the carbon atom has three regions of electron density (two from the hydrogens and one from the oxygen double bond).
- Electron Geometry:
With three regions of electron density, the electron geometry around the carbon atom is trigonal planar. This means that the angle between the bonds is 120°, which is characteristic of sp² hybridization. - Orbital Hybridization:
To form three regions of electron density (three bonds), the carbon atom mixes one s orbital and two p orbitals. This creates three sp² hybrid orbitals. These hybrid orbitals overlap with the orbitals of hydrogen and oxygen to form sigma bonds. The remaining unhybridized p orbital on carbon forms the pi bond in the double bond with oxygen.
Since the electron geometry is trigonal planar, the carbon in formaldehyde undergoes sp² hybridization.
Thus, the correct hybridization for the carbon atom in H₂CO is sp².