1. 11.1 Polarity of Molecules
   1. 2 types intermolecular force ( between dipoles molecules )
      1. 11.2 van der Waals' force
      2. hydrogen bond
   2. Permanent dipole
      1. exist in all polar molecules
      2. The more electronegative atom tend to attract the bonding electron pair closer to itself
         1. become slightly negatively charge
      3. The less electronegative atom become electron deficient
         1. become slightly positive charge
      4. distribution charge not uniform
         1. permanent dipole formed
   3. Instantaneous dipole
      1. In non-polar molecules
         1. halogens, noble gases, oxygen, tetrachloromethane
      2. due to fluctuation of electron clouds from time to time
         1. slightly positive and negative charge exist temporarily
   4. Induced dipole
      1. a dipole molecule close to non-polar molecule
         1. non-polar molecule will be induced
            1. induced dipole formed
2. Simple molecular substances
   1. strong covalent bonds between atoms
   2. weak intermolecular force between molecule
3. 11.2 Van der Waals' Forces
   1. 3 types intermolecular attractions
      1. dipole-dipole interactions
         1. polar molecules have permanent dipole moments
            1. tend to orientate the attractive forces between molecules are maximized while repulsive forces are minimized
         2. the electrostatic attraction between the negative end of polar molecule and positive end of another polar molecule
      2. dipole-induced dipole interactions
         1. non-polar molecule close to polar molecule
            1. non-polar molecule induced to have a induced dipole moment
            2. original dipole molecule attract the induced dipole each other
         2. weaker than dipole-dipole interactions
      3. instantaneous dipole - induced dipole interactions
         1. non-polar molecules (hydrogen, oxygen, halogens, noble gas)
            1. can solidified at low temp.
            2. have attractive force to hold them to form solid lattice
         2. electron cloud is moblie
            1. electron cloud may concentrated on one side of atom at any instant
            2. the atom possess a dipole moment at the particular instant
            3. exist within a very short time
         3. instantaneous dipole molecule induced the neighbouring atom
            1. induced dipole have orientation opposite to that instantanteous dipole
            2. 分支主題 1