1. GENERAL TYPES OF
INTERMOLECULAR
FORCES
January 5, 2017

2. Intermolecular forces are attractive
coulombic interactions between
molecules. One example of coulombic
attraction is in the form of ionic
bonding. This attractive force is
between two oppositely charged ions.

3. The strength of intermolecular forces
determines the state of a substance under a
given set of conditions. HF for example is a
gas at room and ordinary pressure. Under
conditions where HF is less energetic, the
intermolecular forces will draw them closer
together (at either low temperature or higher
pressure), so that the substance is a liquid.
The strength of intermolecular forces also
depends on the molar mass of a substance.
For comparable molar masses
intermolecular forces of attraction increase

4. The discussion on intermolecular forces will
revolve around attractive forces that act
between atoms of molecules of pure
substance. They are collectively called van
der Waals forces. Include in this
category are dipole-dipole
interactions, hydrogen bonding,
dispersion forces, and ion-dipole
interactions.

6. 1. Dipole-dipole interactions
Attractive
forces that act
between polar
molecules.

7. 1. Dipole-dipole interactions
Electrostatic
interactions between
polar molecules

8. 2. Hydrogen bonding
It is a special type of dipole-dipole
interaction. Dipole-dipole
interaction occurs between any
polar molecules. On the other
hand, hydrogen bonding occurs
only in molecules that contain H
bonded to a small, highly
electronegative atom like F, N, and

9. 3. Dispersion forces
Which are attractive forces
between gases like O2 and N2
which can be liquefied under
correct conditions of pressure and
temperature.

10. 4. Ion-dipole interaction
It is the force of attraction
between ion and polar
molecules like NaCl in water
to form an aqueous solution.

11. Different materials have
Different
Uses Depending on their
Properties

12. Uses of Some Common Materials
that Depend on Their Properties
Many of the materials today that we
cannot live without are made of
compounds that belong to the family of
hydrocarbons, namely, alkanes,
alkenes, alkynes, and aromatics.
(Hydrocarbons are compounds that contain
carbon and hydrogen.)

13. 1. Medical implants and
Prosthetics
Biopolymers are used to replace
diseased or damaged body parts such
as hip joints, teeth, heart valves, and
blood vessels. They are also used as
flexible wound dressing, surgical
implants, and prosthetics.
(Polymers are long-chain molecules formed
from many repeating units of small carbon
molecules)

14. 2. Sport equipment
Polystyrene foam is used to make
protective helmets.
Polyvinyl chloride are used as rainwear
and tough plastic coverings.
Polytetrafluoroethene (PTFE), which is
resistant to heat and chemical reaction, can
be used as bearings and bushings for
sports equipment.
Polyisoprene which constitutes rubber can
be used as soles of athletic shoes.

16. Polystyrene foam

17. Polyvinyl chloride

18. Polytetrafluoroethene

19. Polyisoprene

20. 2. Sport equipment
Nylon is molded into gears,
bearings, zippers, and ropes. It
can be used as tire cords,
fishing lines, and vest made of
Kevlar which is strong enough
to stop high-speed bullets.

21. Nylon Products

22. 3. Electronic devices
Nanowires(the world’s smallest
electrical wire) are just 1.5
nanometers thick.
Semiconductors are metalloids that
can be found in between the
metals and the nonmetals in the
periodic table.

24. 3. Electronic devices
Diodes are examples of semiconductor
devices. They restrict the flow of
electrons in one direction. The most
known diodes are the LEDs (light
emitting diodes). LEDs are becoming
popular nowadays and people are now
replacing their incandescent and
fluorescent lamps with LEDs for exit
signs, car taillights, billboards, traffic
lights, and signals.

25. LED

26. LED billboards

27. 4. Construction supplies for
buildings and furniture.
Synthetic rubber is used for
electrical installations in buildings
and houses. Synthetic polymers are
also used as carpeting materials,
plastic covers, plastic pipes, flooring
materials, and for walling. Butanone
is used to remove paint.

28. 5. Household gadgets
Plastic industry has learned to
produce synthetic polymers that are
used in fabricating household
gadgets and furniture.
(plastic bottles, drinking glasses,
nonstick pans)

29. 5. Household gadgets
Polyethylene is a polymer used in
the manufacture of plastic bottles,
plastic dinnerware, and garden
hose.
Teflon, a household brand which is
made of Tetrafluoroethylene is a
very good insulator and used for
nonstick pans. Polyacrylonitrile
named Orlon is used as fiber for