Why do you think is CCl2O much less polar than CH2O
The Correct Answer and Explanation is:
CCl2O (carbonyl dichloride) is much less polar than CH2O (formaldehyde) due to the difference in electronegativity of the atoms involved and the molecular geometry of the two compounds.
In CH2O, the central carbon atom is double-bonded to an oxygen atom and single-bonded to two hydrogen atoms. The oxygen atom, being highly electronegative, pulls electron density away from the carbon, creating a partial negative charge on oxygen and a partial positive charge on carbon. This generates a significant dipole moment. The overall structure of CH2O is polar because the bond dipoles between carbon-oxygen and carbon-hydrogen do not cancel out, due to the asymmetric arrangement of the atoms.
On the other hand, in CCl2O, the central carbon is double-bonded to an oxygen atom and single-bonded to two chlorine atoms. Chlorine is also highly electronegative, similar to oxygen, but the difference in electronegativity between chlorine and carbon is not as large as that between oxygen and carbon. Additionally, chlorine atoms are much larger than hydrogen atoms and are positioned symmetrically around the carbonyl group. This symmetry allows the bond dipoles between the carbon-chlorine bonds to effectively cancel each other out, reducing the overall dipole moment of the molecule. Although CCl2O has polar bonds, the symmetry and the partial cancellation of dipoles make the molecule overall less polar than CH2O.
Thus, CH2O exhibits a stronger net dipole moment because of the asymmetry of the molecule and the significant electronegativity difference between carbon and oxygen. In contrast, CCl2O’s symmetric structure and less pronounced electronegativity differences result in a weaker overall dipole moment, making it less polar.
