Question

Which of the following molecule has the highest dipole moment?

• A. NH\(_3\)
• B. NF\(_3\)
• C. CCl\(_4\)
• D. BeF\(_2\)
• E. BF\(_3\)

Hint:

For molecules to have a non-zero dipole moment, the individual bond dipoles must not cancel out. Molecules with a symmetric shape (like BF\(_3\), CCl\(_4\), BeF\(_2\)) tend to have zero net dipole moments, while molecules with an asymmetrical shape (like NH\(_3\)) can have a non-zero dipole moment due to the arrangement of atoms and lone pairs of electrons.

Answer 1

The Correct Option is A

The dipole moment of a molecule is a vector quantity which depends on the magnitude of the bond dipoles and the angle between them. Molecules like NH\(_3\) have a higher dipole moment because of the following reasons:
- NH\(_3\) (Ammonia) has a trigonal pyramidal structure, where the nitrogen atom has a lone pair of electrons that contributes to the dipole moment. The dipoles do not cancel each other out, leading to a net dipole moment.
- NF\(_3\), BeF\(_2\), CCl\(_4\), and BF\(_3\) are all molecules with a symmetric shape (tetrahedral or linear). In these molecules, the dipole moments of individual bonds cancel each other out, resulting in a net dipole moment of zero or a smaller dipole moment compared to NH\(_3\).
Therefore, the molecule with the highest dipole moment is NH\(_3\).