Intermolecular forces

An intermolecular force is a force of attraction or repulsion between molecules (as opposed to intramolecular forces within a single molecule, such as ionic bonds or covalent bonds). There are three main intermolecular forces, and they are referred to collectively as van der Waals forces. They are all much weaker than intramolecular bonds. They affect melting points and boiling points, surface tension, the shape of the meniscus, capillary action, volatility, and the solubility of substances. There are three main van der Waals forces:

dipole–dipole

a force of attraction between polar molecules due to the simultaneous attraction between a dipole and surrounding dipoles; its strength is dependent on the polarity of the molecule

London

the simultaneous attraction of an electron by nuclei within a molecule and by nuclei in adjacent molecules; its strength is directly related to the number of electrons in the molecule

Hydrogen bonding

the attraction of hydrogen atoms bonded to N, O, or F atoms to a lone pair of electrons of N, O, or F atoms in adjacent molecules; stronger than the dipole–dipole force and the London force