1. 12.1 Intramolecular Forces
“Within” the molecule and are called covalent and ionic bonds.
Molecules are formed by sharing electrons between the atoms.
Covalent bonds hold the atoms of a molecule together.
Ionic bonds hold oppositely charged ions together in a formula unit

2. 12.1 Intermolecular Forces
Forces that occur between molecules.
Intramolecular (ionic and covalent) bonds are stronger than intermolecular forces.

3. 12.6 Intermolecular Forces
There are two kinds of intermolecular forces that occur between molecules.
Dipole–dipole forces (between polar molecules)
Hydrogen bonding (between hydrogen of one polar molecule and O, N, F of another polar molecule)
London dispersion forces (between nonpolar molecules)

4. 12.6 Dipole–Dipole Attraction
Polar molecules contain different
atoms which have different
electronegativity's and can be
thought to be like a small bar
magnet. Oppositely charged ends attract and like ends repel. Molecules organize themselves to maximize the attractive forces
and minimize repulsive forces
giving molecules unique shapes.

5. 12.6 Hydrogen Bonding Strong dipole-dipole forces.
Hydrogen is bound to a highly electronegative atom – nitrogen, oxygen, or fluorine.

6. 12.6 Hydrogen Bonding in Water
Blue dotted lines are the intermolecular forces between the water molecules.

7. 12.6 London Dispersion Forces
Become stronger as the sizes of atoms or molecules increase.

8. Ion Dipole Forces
Ion Dipole forces are typically found in aqueous solutions of ionic compounds, such as salt water. In the figure below the nonbonding electrons found on the oxygen atom are strongly attracted to the sodium ion.

9. Overview of Particle Forces
Type of Force Relative Strength Present in Examples
Dispersion Force
(London Force)
Weak, increasing with size
atoms/molecules
H2 (g)
Polar molecules
HCl
Dipole-dipole force
moderate
Molecules with hydrogen bonded to N,O, or F
Hydrogen bond
Strong
HF, NH3, H2O
Ion-dipole
Very strong
Mixtures of ionic and polar compounds
Na+,Cl-, and H2O