Dispersion forces are the weakest force of attraction. They may also be called London forces.
- Dispersion forces are weak attractive forces between all molecules due to the random movement of electrons around atoms and molecules forming momentary charges (instantaneous dipoles).
They are caused by the attraction between negatively charged electrons of one molecule and the positively charged nuclei of the atom in another molecule.
They are found in molecules which have no difference in electronegativity. It is also seen in molecules which have polar bonds, however they can be balanced out with structure of the molecule, subsequently making it non-polar. This is evident in the CO2 molecule. http://socratic.org/questions/what-type-of-intermolecular-force-of-attraction-is-found-in-co2-1.
The larger the molecule, with dispersion forces, the higher the melting point. E.g. This is seen in the halogens, where the Cl2 molecule has a lower boiling point than the I2 molecule.
To gain more understanding about attractive forces, I recommend you research these other intermolecular forces:
- Hydrogen Bonds
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