Intermolecular Forces

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Intermolecular Forces

• Honors Chemistry
• Mrs. Coyle

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Intermolecular Forces

• The forces with which molecules attract each
  other.

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Intermolecular Forces

• Intermolecular forces are weaker than ionic or
  covalent bonds.
• Intermolecular forces are responsible for the
  physical state of a compound (solid, liquid or
  gas).

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Intermolecular Forces

• Van der Waals Forces
• Dipole-Dipole Interactions
• Dispersion Forces (London forces)
• Hydrogen Bonds

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Van der Waals Forces

• They are the weakest attractions between
  molecules.

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Dipole

• A polar molecule.

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Van der Waals-Dipole-Dipole Interactions

• Electrostatic interaction between the oppositely
  charged regions of polar molecules (dipoles).

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Which Molecules have Dipole Interactions?
Polar
Non-polar
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Van der Waals Forces-Dispersion Forces

• Dispersion Forces
• Caused by the motion of electrons.
• Increase as the number of electrons increases.
• Induced (temporary) dipole.

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Hydrogen Bonding

• Hydrogen covalently bonded to a very
  electronegative element
• Hydrogen is also weakly bonded to an unshared
  pair of electrons in another molecule.
• This is possible with hydrogen because there is
  no shielding of the nucleus.
• N, O, F

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Dipole Interactions