[mm12024]

According to my chemistry textbook London dispersion forces are stronger than dipole-dipole forces. I don't understand why this is true because London dispersion forces are instantaneous attractions and dipole-dipole are permanent?
If anyone could explain I would be very grateful.
Thanks

[Sophia7X]

Not always. I think dipole-dipole forces are usually stronger than dispersion.

There are cases when dispersion forces > dipole dipole forces (if there are a lot of electrons in the molecule and the molecule isn't extremely polar). Dispersion forces are present between all molecules.