[vanderwaals]

Why does NCl₃ have a greater dipole moment than NF₃? It seems to make more sense for NF₃ to have the greater dipole moment because F is more electronegative than Cl, and both molecules have the same molecular geometry (trigonal pyramidal).

[AWK]

Pay attention to the difference in bond legths.

[vanderwaals]

Thanks for the helpful response! How would you know if the increase in bond length has a greater effect than a decrease in electronegativity? For example, HF has a greater dipole moment than HCl even though HF has a smaller bond length. How do you know which factor dominates?