Why is the dipole moment of NH3 greater then that of NF3 ??

Dipole moment of  NH3 is higher than NF3 molecule. 


  • Both the molecules have pyramidal shape with a lone pair of electrons on nitrogen atom. 
  • Although fluorine is more electronegative than nitrogen, the resultant dipole moment of NH3 ( 4.90 × 10–30 C m) is greater than that of NF3 (0.8 × 10–30 C m). 
  • This is because, in case of NH3 the orbital dipole due to lone pair is in the same direction as the resultant dipole moment of the N – H bonds, 
  • whereas in NF3 the orbital dipole is in the direction opposite to the resultant dipole moment of the three N–F bonds. The orbital dipole because of lone pair decreases the effect of the resultant N – F bond moments, which results in the low dipole moment of NF3

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