Which of the following molecule has highest dipole moment ?

Question

Accepted Answer

The molecule with the highest dipole moment among the given options is $NH_{3}$ (ammonia). Here's a detailed explanation supporting why Option 1 is correct and why the other options are incorrect:

1. **$NH_{3}$ (Ammonia):**
   - Ammonia has a trigonal pyramidal shape due to the presence of a lone pair on the nitrogen atom. This lone pair causes a distortion in the geometry, resulting in a net dipole moment.
   - The nitrogen atom is more electronegative than hydrogen, which creates a significant dipole moment directed from the hydrogen atoms towards the nitrogen atom.
   - The geometry and the difference in electronegativity between nitrogen and hydrogen lead to a relatively high dipole moment for $NH_{3}$, which is approximately 1.47 Debye.

2. **$CCl_{4}$ (Carbon Tetrachloride):**
   - Carbon tetrachloride is a tetrahedral molecule with four chlorine atoms symmetrically surrounding a central carbon atom.
   - Although there is a significant electronegativity difference between carbon and chlorine, the symmetry of the molecule causes the dipole moments to cancel each other out.
   - As a result, $CCl_{4}$ is a nonpolar molecule with a net dipole moment of zero.

3. **$NF_{3}$ (Nitrogen Trifluoride):**
   - Nitrogen trifluoride has a similar trigonal pyramidal shape to ammonia, but the electronegativity difference between nitrogen and fluorine is less favorable for a high dipole moment compared to $NH_{3}$.
   - The dipole moment of $NF_{3}$ is lower than that of $NH_{3}$ because the lone pair on nitrogen and the bond dipoles between nitrogen and fluorine partially cancel each other out.
   - The dipole moment of $NF_{3}$ is approximately 0.24 Debye, which is significantly lower than that of $NH_{3}$.

4. **$BF_{3}$ (Boron Trifluoride):**
   - Boron trifluoride is a planar trigonal molecule with three fluorine atoms symmetrically arranged around a central boron atom.
   - Despite the high electronegativity of fluorine, the symmetry of the molecule leads to the cancellation of individual bond dipoles.
   - Consequently, $BF_{3}$ is a nonpolar molecule with a net dipole moment of zero.

In conclusion, $NH_{3}$ has the highest dipole moment among the given options due to its molecular geometry and the significant electronegativity difference between nitrogen and hydrogen, which results in a net dipole moment. The other molecules either have symmetrical structures that lead to dipole cancellation or have lower dipole moments due to less favorable electronegativity differences and molecular geometry.