INTERMOLECULAR FORCES

1. Section 10.1
Intermolecular Forces
How can a gecko’s feet stick to almost
any surface?

2. Section 10.1
Intermolecular Forces
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Intramolecular Bonding
 “Within” the molecule.
 Molecules are formed by sharing
electrons between the atoms.

3. Section 10.1
Intermolecular Forces
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Intermolecular Forces
 Intermolecular forces are the attractive
force or interaction between molecules.

4. Section 10.1
Intermolecular Forces

5. Section 10.1
Intermolecular Forces
Four kinds of Intermolecular Forces
 Hydrogen Bond
 Dipole-Dipole Force
 Ion-Dipole Force
 Dispersion or London Force

6. Section 10.1
Intermolecular Forces
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Hydrogen Bonding
 Strong dipole-dipole forces.
 Hydrogen is bound to a highly electronegative
atom – nitrogen, oxygen, or fluorine.
 That same hydrogen is then electrostatically
attracted to a lone pair on the nitrogen,
oxygen or fluorine on adjacent molecules.

7. Section 10.1
Intermolecular Forces
Hydrogen Bonding in Water
 Blue dotted lines are the intermolecular forces between
the water molecules.

8. Section 10.1
Intermolecular Forces
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Dipole-Dipole Forces
 Dipole moment – molecules with polar bonds often
behave in an electric field as if they had a center of
positive charge and a center of negative charge.
 Molecules with dipole moments can attract each
other electrostatically. They line up so that the
positive and negative ends are close to each other.
 Only about 1% as strong as covalent or ionic bonds.

9. Section 10.1
Intermolecular Forces
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Dipole-Dipole Forces

10. Section 10.1
Intermolecular Forces
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Ion-Dipole Forces
 Ions have full charges that are attracted to
the partial charge on polar molecules.

11. Section 10.1
Intermolecular Forces
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Ion-Dipole Forces

12. Section 10.1
Intermolecular Forces
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London Dispersion Forces
 Instantaneous dipole that occurs
accidentally in a given atom induces a
similar dipole in a neighboring atom.

13. Section 10.1
Intermolecular Forces
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London Dispersion Forces