Intermolecular forces

1
Intermolecular forces

• Dipole- dipole
• Hydrogen bonding
• London dispersion forces

2
Dipole

• An intramolecular dipole is created by equal but
  opposite charges that are separated by a short
  distance.
• Direction partial positive end to negative end

3
Dipole - dipole

• Very strong
• Force of attraction between polar molecules.

4
polarity

• Diatomic determined by one bond
• Molecule with more than 2 atoms the geometry also
  plays a role in determining polarity.
• Sometime geometry cancels out individual bond
  dipoles like in carbon dioxide and carbon
  tetrachloride

5
polarity

• Water - polar molecule

6
Induced dipole

• A polar molecule can induce dipoles in other
  molecuels.
• Short range
• Weaker than dipole-dipole
• Solubility of oxygen in water

7
Hydrogen bonding

• The intermolecular force in which a hydrogen
  atoms, that is bonded to a highly electronegative
  atom, is attracted to an unshared pair of
  electrons of an electronegative atom in a nearby
  molecule.
• Dotted lines

8
London dispersion forces

• The intermoleuclear attractions resulting from
  the constant motion of electrons and the creation
  of instantaneous dipoles.