Intermolecular Forces
World A — Chemistry Foundations
R09.01 Intra vs Inter
- Intra = Within molecule (Strong).
- Inter = Between molecules (Weak).
- IMFs dictate physical state.
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R09.02 Dipole-Dipole
- Between polar molecules.
- Positive end attracts negative end.
- Permanent electrostatic pull.
R09.03 Hydrogen Bonding
- Extreme dipole-dipole force.
- H bonded to N, O, or F.
- Gives water high boiling point.
R09.04 London Dispersion
- Found in all molecules.
- Temporary, induced dipoles.
- Stronger in larger electron clouds.
Na⁺
R09.05 Ion-Dipole Force
- Between an ion and polar molecule.
- Reason salts dissolve in water.
- Hydration shells form around ions.
R09.06 Boiling & Melting
- Heat must overcome IMFs.
- Stronger IMFs = Higher BP/MP.
- Molecules separate, bonds remain intact.
R09.07 Viscosity
- Resistance to liquid flow.
- Higher IMFs = Higher viscosity.
- Decreases as temperature rises.
R09.08 Surface Tension
- Inward pull of surface molecules.
- Creates an elastic "skin".
- Water forms drops due to H-bonds.