All molecules can interact with other molecules, having the ability to either attract or repel one another. There are several important forces that govern the interactions of molecules; it is the nature of these forces that directly determines the melting points, boiling points, and solubility properties of a particular compound. The most important forces found in organic molecules are London dispersion forces, dipole-dipole interactions, and hydrogen bonding.

London Dispersion Forces

            London forces, one of the van der Waals forces, are the interactions between temporary dipoles, a momentary separation of charge. Electrons are in constant motion, and, at any given moment, the movement of a single electron can disrupt the symmetrical electron distribution on a molecule, creating a temporary dipole that lasts for a fraction of a second.

London forces: The random movement of electrons causes a temporary dipole moment

          These partial charges on the molecule can then interact with partial charges on other molecules. These forces are very weak; however, the sum of many of these small forces can lead to a very significant net force.