van der Waals force

1. A weak force of attraction between electrically neutral molecules that collide with or pass very close to each other. The van der Waals force is caused by the attraction between electron-rich regions of one molecule and electron-poor regions of another (the attraction between the molecules seen as electric dipoles). The attraction is much weaker than a chemical bond. Van der Waals forces are the intermolecular forces that cause molecules to cohere in liquid and solid states of matter, and are responsible for surface tension and capillary action.