11.1 Intermolecular Forces
PRE-HEALTH PREP
Hydrogen Bonding
-a super strong dipole-dipole force
-must have an F-H, O-H, or N-H bond as a pure liquid
-must only have F, O, N to hydrogen bond with water (or other H-bond donor)
Dipole-Dipole Forces
-interaction between molecules having permanent dipole moments
-the larger the dipole moment, the larger the force
London Dispersion Forces
(van der Waals Forces)
-weak interactions due to a transient (temporary) dipole
-all molecules have these but is the only force present for nonpolar molecules
-higher molecular weight, larger surface area, and greater polarizability result in higher London forces
Ion-Dipole Forces
-interaction between ions and polar molecules
-present when ions are dissolved in polar liquids (such as NaCl in H2O)
| INTERMOLECULAR FORCES | |
|---|---|
| Hydrogen Bonding | -a super strong dipole-dipole force-must have an F-H, O-H, or N-H bond as a pure liquid-must only have F, O, N to hydrogen bond with water (or other H-bond donor) |
| Dipole-Dipole Forces | -interaction between molecules having permanent dipole moments-the larger the dipole moment, the larger the force |
| London Dispersion Forces(van der Waals Forces) | -weak interactions due to a transient (temporary) dipole-all molecules have these but is the only force present for nonpolar molecules-higher molecular weight, larger surface area, and greater polarizability result in higher London forces |
| Ion-Dipole Forces | -interaction between ions and polar molecules-present when ions are dissolved in polar liquids (such as NaCl in H2O) |
Higher Intermolecular Forces Result in:
↑ Higher Boiling Pts
↑ Higher Enthalpy of Vaporization
↑ Greater Viscosity
↑ Greater Surface Tension
↑ Higher Critical Temperature/Pressure
↓ Lower Vapor Pressure
In each set choose the molecule which has the greatest overall intermolecular forces?
CH4
CH3CH3
CH3CH2CH3
CH3F
CH3CH3
CH3OH
CH4
CH3CH3
CH3F
CH3CH3
CH3F
CH3CH2CH3