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INTERMOLECULAR FORCES

(The force will be with you, always)

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Intramolecular bonds and Intermolecular Forces

  • Intramolecular bonds are the bonds within the molecule. (covalent bonds)
  • Intermolecular forces are the forces of attraction between molecules due to polarity and movement of electrons within the bond.
  • The more polar the molecule, the stronger the intermolecular force.

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Intermolecular forces

  • Intermolecular forces are weaker than ionic or covalent bonds.
  • The strength of the intermolecular force determines the phase (solid, liquid, or gas) that the molecules have.
  • Strong forces: solid phase
  • Weak forces: gas phase
  • The larger the polarity of the molecule, the stronger the intermolecular force between molecules.

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Intramolecular bonds and Intermolecular Forces

  • Intramolecular bonds are the bonds within the molecule. (covalent bonds)
  • Intermolecular forces are the forces of attraction between molecules due to polarity and movement of electrons within the bond.
  • The more polar the molecule, the stronger the intermolecular force.

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intermolcular forces

  • Intermolecular forces are weaker than ionic or covalent bonds.
  • The strength of the intermolecular force determines the phase (solid, liquid, or gas) that the molecules have.
  • Strong forces: solid phase
  • Weak forces: gas phase
  • The larger the dipole moment (the polarity of the molecule), the stronger the intermolecular force between molecules.

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Three types of intermolecular forces

  • London force: also known as the Dispersion force (Weakest)
  • Dipole-dipole forces (middle)
  • Hydrogen bond (strongest)

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London / dispersion forces

  • Weakest force
  • The only force of attraction between two nonpolar molecules.
  • All molecules (both polar and nonpolar) have some London forces between them.
  • Due to the random back and forth movement of shared electrons.

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Dipole-Dipole forces

  • Force of attraction between two polar molecules.
  • The larger in size of the polar molecule, the weaker the dipole force because the molecules can’t get as close to each other.

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Induced Dipole

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Hydrogen Bonds

  • Attraction occuring when a hydrogen atom is bonded to a strongly electronegative atom (such as fluorine, oxygen, or nitrogen)
  • This happens because hydrogen is so small in size, it can get close to another molecule and therefore have a greater effect.

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Hydrogen Bonding

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Intermolecular forces

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London

Dipole-dipole

Hydrogen Bonding