Intermolecular Forces

• What is the strongest intermolecular force?

  Hydrogen
• Which is the weakest intermolecular force?

  London forces
• Order the 2 types of intermolecular forces from strongest to weakest

  Hydrogen

  Permanent dipole-dipole

  London Forces
• Is CCl4 polar or non-polar?

  Non-polar

  because the molecule is symmetrical so the dipoles cancel out
• London Forces:

  1. Electrons are evenly distributed
  2. Due to movement of electrons in molecules
  3. Electrons are unevenly distributed in one molecule which creates a temporary dipole
  4. This then leads to an induced dipole in the next molecule
  5. Dipoles on each molecule attract each other creating a london force
• How strong are London Forces?

  Occur due to an uneven distribution of electrons therefore:

  more electrons

  bigger dipoles

  allows a bigger attraction between molecules
• Why does the bp increase as you go down group 7?

  London forces become more stronger as there are more electrons
• Which molecules does hydrogen bonding occur with?

  F, O, N
• How do hydrogen bonds form in H2O?

  hydrogen bonds form between lone pairs of electrons on oxygen on one molecule and hydrogen on another
• Why can ethanol and water mix together?

  Both ethanol and water have O-H bonds

  Hydrogen bonds form between ethanol and H2O molecules

  Allowing them to mix