NH3 and NF3 are isostructural with one lone pair on N-atom, but dipole moment of NH3 is
greater than that of NF3. Explain.
Answers
follow mee
Whose dipole moment is greater NH3 or NF3?
Share your DIY projects online and earn a profit with Kajabi!
In NH3, N is the most electronegative element while in NF3, F is the most electronegative element. But in both the molecules, a lone pair of electrons is present.
So,in addition to bond polarity and structure, the unshared pair of electrons also influence dipole moment values.
The dipole moment of NF3 is expected to be larger than NH3. But the actual value of D.M of NF3 is 0.23D while that of NH3 is 1.46D ( where D is Debye).
In,NH3 the nitrogen being more electronegative and so the N-H bond is pointing towards N. A lone pair of electrons is attached on one side only and hence its other end becomes the negative end of a dipole, the bonded end being positive. This contributes a moment called lone-pair moment.
In NH3, the (3) H-N and (1 ) N-lone pair dipoles are in the same direction. That is, the H-N dipoles strengthen and reinforce the lone pair dipole. Therefore the vector sum of the four dipole moments is high (1.46D).
In NF3, the F-N dipoles are opposed to the N-lone pair dipole. That is, the 3 F-N dipoles weaken the lone pair dipole and vice versa. Thus the vector sum of the four dipole moments becomes low and has a value of 0.23D. The lone pair moment is also called “orbital moment”.
Answer:
different
Explanation: