What are some examples of Van der Waals forces?

Van der Waals forces are attractive forces that hold molecules close together. These attractive forces are more commonly referred to as intermolecular forces (IMF). The three most common types of Van der Waals forces (intermolecular forces), listed below from weakest to strongest, are:

1. London Dispersion forces 2. Dipole-Dipole forces 3. Hydrogen [bonding](http://socratic.org/chemistry/bonding-basics/bonding) (not REALLY a bond!).

All three of these types of Van der Waals forces arise due to attraction between oppositely charged areas of substances. London dispersion forces, the weakest of the Van der Waals, arise from temporary charge development that occurs spontaneously in all , even in neutral atoms.

Dipole-dipole forces, moderately strong Van der Waals forces, occur among substances with permanent, although partial charge development. For example, hydrochloric acid experiences dipole-dipole attractions. Neither the hydrogen nor the chlorine have full charges, but they do have different electron densities, which gives rise to partial charge development.

Hydrogen bonding, the strongest of the Van der Waals forces, is an especially strong type of dipole-dipole force. Hydrogen bonding arises only between molecules that have hydrogen atoms directly bonded to a very electronegative atom, specifically either fluorine, oxygen or nitrogen, which enhances partial charge development. Water is a great example of a molecule that experiences hydrogen bonding, which gives rise to the many unique properties of this universal !