London dispersion forces

• Permanent dipoles can induce dipoles in non-polar molecules by pulling / pushing the electrons across the other molecule
• As electron density fluctuates at all times, if the electron density ever becomes unsymmetrical, an instantaneous dipole will be generated
• The end where the electron density increases will have a $\delta$ - charge
• The $\delta$ + will attract electrons from another molecule, and the $\delta$ - will repel electrons from another molecule, moving the electron density, creating an induced dipole in the other molecule
• The induced dipole will always be aligned so the interaction with the instantaneous dipole is favourable
• London forces are the weakest type of Van der Waals forces, but the attractive force is stronger with more electrons
• All molecules (polar and non-polar) will experience instantaneous dipoles caused by the movement of electrons