Intermolecular Forces
Learning Objectives
the relative strengths of bonds (covalent bonding, dispersion forces, dipole-dipole attraction and hydrogen bonding) and evidence and factors that determine bond strength including explanations for the floating of ice and expansion of water at higher temperatures.
Summary Notes
INTRAmolecular vs INTERmolecular forces
Intramolecular forces are the forces between covalent bonding within molecules.
Intermolecular forces are the forces of attraction between molecules that hold molecules together.
Weakest Intermolecular Force: Dispersion
Present in all molecules
Depends on 'instantaneous dipole'
Forces of attraction are between the instantaneous positive end of one molecule and the negative end of another molecule.
Stronger Intermolecular Force: Dipole-Dipole
Present in polar molecules
Permanent dipole
Forces of attraction are between positive end of one molecule and negative end of another
Strongest Intermolecular Force: Hydrogen Bonding
Hydrogen bonding is the force of attraction between the hydrogen atom on one molecule and the fluorine, oxygen or nitrogen atom on another molecule.
Video to help build your understanding
*Note: Van der Waal/ London forces which are mentioned in this video are the same as 'dispersion' forces