Intermolecular attractions are weak forces which hold neighbouring molecules together.
There are three main types:
- All molecules will have instantaneous dipole-induced dipole attractions between them. They occur when the random movement of electrons in one molecule induce a dipole in a neighbouring molecule. The two dipoles then attract each other. The strength of the attraction depends upon the size of the molecule.
- Molecules that are polar will have additional permanent dipole-permanent dipole attractions.
- In addition, some molecules will be able to hydrogen bond to each other. A positively charged hydrogen in one molecule interacts with a lone pair of electrons on a neighbouring molecule. This is the strongest type of intermolecular attraction.
Now try the following activity.