NEETChemistryChemical Bonding and Molecular Structure
Which of the following statements correctly compares the dipole moments of NH ₃ and NF ₃ and provides the appropriate reason?
Options
- ANF ₃ > NH ₃ because fluorine is more electronegative than hydrogen, resulting in highly polar N-F bonds.
- BNH ₃ > NF ₃ because the orbital dipole of the lone pair is in the same direction as the resultant of the N-H b
- CNH ₃ > NF ₃ because the N-H bonds are intrinsically more polar than the N-F bonds.
- DNF ₃ > NH ₃ because the lone pair orbital dipole in NF ₃ aligns with and enhances the resultant of the N-F bon
Correct answer
B. NH ₃ > NF ₃ because the orbital dipole of the lone pair is in the same direction as the resultant of the N-H b
Step-by-step solution
The dipole moment of NH ₃ ( 1.47 D ) is greater than that of NF ₃ ( 0.23 D ). Both molecules have a trigonal pyramidal geometry with one lone pair on the central nitrogen atom. In NH ₃ , nitrogen is more electronegative than hydrogen, so the N-H bond dipoles point towards nitrogen. The resultant of the three N-H bond dipoles is in the same direction as the orbital dipole of the lone pair, leading to a higher net dipole moment. In NF ₃ , fluorine is more electronegative than nitrogen, so the N-F bond dipoles point t