Which of the following best describes the overall molecular dipole moment of acetone (CH3COCH3) using a vector arrow?

• A. A single arrow pointing from the central carbon atom (C=O) towards the oxygen atom, indicating a net dipole towards oxygen.
• B. An arrow pointing from the oxygen atom towards the central carbon atom, indicating a net dipole towards carbon.
• C. No arrow, indicating that acetone is a nonpolar molecule with no net dipole moment.
• D. Two arrows of equal length pointing from each methyl group towards the central carbon atom, indicating no net dipole.

Answer: (A)

Verified step by step guidance

1. Understand that a molecular dipole moment arises from differences in electronegativity between atoms and the geometry of the molecule, resulting in a net vector sum of individual bond dipoles.
2. Identify the key polar bond in acetone (CH3COCH3), which is the carbon-oxygen double bond (C=O), because oxygen is more electronegative than carbon, creating a dipole pointing towards oxygen.
3. Recognize that the methyl groups (CH3) attached to the central carbon are relatively nonpolar and their bond dipoles largely cancel out due to molecular symmetry.
4. Represent the overall dipole moment as a single vector arrow starting at the central carbon atom of the C=O group and pointing towards the oxygen atom, indicating the net dipole direction.
5. Conclude that this vector arrow correctly shows the net dipole moment of acetone, pointing from the less electronegative carbon towards the more electronegative oxygen atom.