INTERMOLECULAR (IM)
FORCES
*without them,
all matter would be gases*
intermolecular forces: forces of attraction between molecules
4 TYPES OF IM FORCES (in order from strongest to weakest)
1.
HYDROGEN "BONDING"
* occurs between molecules that have
hydrogen & nitrogen, hydrogen & oxygen, and
hydrogen &
fluorine
* accounts for the unusually high
boiling point of NH3, H2O, and HF
2.
DIPOLE-DIPOLE FORCES
* occurs between polar molecules (dipoles)
* the slightly positive end of one
polar molecule is attracted to the slightly negative end
of another polar
molecule
3.
DIPOLE-INDUCED DIPOLE FORCES
* occurs between a polar molecule
(dipole) and a nonpolar molecule or between a polar
molecule and a
noble gas
* the slightly positive end of a
polar molecule temporarily attracts the electrons from a
nonpolar molecule or noble gas
4. LONDON
DISPERSION FORCES
* occurs between all molecules
* only force that acts between nonpolar molecules and noble gases
* moving electrons (in electron
cloud of an atom) temporarily attract the electrons from
another atom
**
COVALENT BONDING IS STRONGER THAN ANY OF THESE IM FORCES. **