Question

What are London forces?

Answer 1

London Force (Dispersion Force): The force of attraction between the induced momentary dipoles are called as the London/dispersion force.

This force arise from the motion of electrons.

It is believed that, at any instant of time ,the electron cloud of the molecule may be distorted to produce a momentary dipole (i.e. a dipole for a moment) in which one part of the molecule becomes slightly negative and thus the momentary dipole induces dipoles in the neighboring molecules.

Now, these molecules are attracted as general dipoles and the force of attraction is the actual London force. This force is found between non-polar molecules like : H₂ , O₂ , N₂ etc and in mono atomic gases like ; He, Ne, Ar etc.