Intermolecular forces of attraction

• Intermolecular forces of attraction

  Attractive forces present in between molecules
• Types of intermolecular forces of attraction

  • London dispersion forces
  • Dipole-dipole forces
  • Ion-dipole forces
  • Hydrogen bonding forces
• Ion-ion interaction


  Interaction between two oppositely charged particles
• Ion-dipole interaction


  Electrostatic attraction of a molecule containing a dipole and an ion
• Dipole-dipole interactions


  Attractive forces present between polar molecules
• Hydrogen bonding


  Special kind of dipole-dipole force that exists when hydrogen is bonded to the most electronegative atoms (F, O, or N)

  
• London dispersion forces (LDFs)


  Weakest type of intermolecular force, present between all electrically neutral molecules
• Induced dipoles


  Occur when a nonpolar atom becomes polar due to the presence of an ion or a dipole
• The strength of ion-ion interactions is dependent on the coulombic force between the particles
• The strength of ion-dipole interactions depends on the charge of the ion present
• The strength of LDFs depends on the polarizability of the molecule
• Polarizability


  Measure of how easy it is to distort the electron distribution of a molecule
• Predicting intermolecular forces of attraction

  1. Determine the type of compound present

  2. Check for polarity of bonds and molecular geometry

  3. Identify presence of hydrogen bonding

  
• The order from weakest to strongest IMFA is: London dispersion forces (Propane), Dipole-dipole forces (Hydrogen Sulfide), Hydrogen bonding (Methanol)