Which of the following statements about dipole moments is correct?

• A. All molecules with polar bonds have a net dipole moment.
• B. Dipole moments only occur in ionic compounds.
• C. A molecule with a dipole moment must be linear.
• D. A dipole moment arises when there is an uneven distribution of electron density between atoms in a molecule.

Answer: (D)

Verified step by step guidance

1. Understand the concept of a dipole moment: It is a measure of the separation of positive and negative charges in a molecule, resulting from an uneven distribution of electron density.
2. Recognize that dipole moments arise due to differences in electronegativity between atoms, causing polar bonds, but the overall molecular shape affects whether these dipoles add up to a net dipole moment.
3. Evaluate the first statement: Not all molecules with polar bonds have a net dipole moment because the molecular geometry can cause individual bond dipoles to cancel out.
4. Evaluate the second statement: Dipole moments are not limited to ionic compounds; they also occur in covalent molecules with polar bonds.
5. Evaluate the third statement: Molecules with dipole moments can have various shapes, not just linear; molecular geometry plays a key role in the presence and direction of dipole moments.