Van der waals forces
Electronic charge around an atom fluctuates, which means that charge distribution isn't symmetrical. Atoms induce complementary asymmetry in neighbouring atoms. The atoms then attract each other. Attraction increases as the two atoms come closer together until they are separated by van der waals contact distance, which is where repulsive forces become dominant because the outer electron clouds of the two atoms overlap. The effect of van der waals forces is larger for larger molecules.
As two atoms closely move towards each other at a certain distance they experience a weak attractive force know as Van der Waals attraction. This results in a distance at which attractive and repulsive forces balance out to produce an energy minimum in each atoms interaction with another non-bonded element.
Van der Waals forces are stronger in an atom, or a molecule, with the greater number of electrons; provided that the atoms are of the same size. If the sizes are different and the number of electrons are equal then van der waals forces are stronger in the smaller atom.
- ↑ Alberts, Bruce. "2." Molecular Biology of the Cell. 5th ed. New York: Garland Science, 2008. 51. Print.