Class notes on Kinetic Particle Theory

1. Bellwork
Answer choices:
1st Law of Thermo, 2nd
Law of Thermo
1. __________ : Heat cannot be created or
destroyed
2. __________ : Heat moves from warm areas
to cold areas.

2. Kinetic Particle Theory

3. What is Kinetic Particle Theory?
all matter is made up of
tiny particles (Molecules)
and that these particles are
in
constant, random motion.

4. Con’t
• When heat is added matter, the
molecules vibrate faster.
• The molecules will change its state
of matter based on how fast they are
vibrating.
• Vibration = Temperature

5. Video
• Summary
• What did you learn from the
video?
• 3 bullets

6. After you completed the first
page:
• https://phet.colorado.edu/
• In search bar, type States of Matter Basic

7. Three States of Matter
ICE WATER STEAM
Solid Liquid Gas

8. Properties of Solid, Liquid & Gas
Properties Solid Liquid Gas
Sample picture
of how the
particles are
arranged
Shape
Volume
Compressibility
Fixed
Fixed Fixed
Not fixed
Not fixed
Not fixed
Cannot be
compressed
Cannot be
compressed
Can be
compressed

9. Properties Solid Liquid Gas
Motion of
molecules
Arrangement of
molecules
Intermolecular
forces
Distance between
molecules
Energy of the
particles
Vibrations about
fixed position only
Arranged in fixed
and orderly
arrangement
Slide past &
movement
through liquid
No fixed
arrangement
Vibrations and
movement
anywhere
No fixed
arrangement
Very strong Weak Negligible
Packed very
close together
Not so closely
packed
Very far apart
According to Kinetic Particle Theory
Less energy than
liquids or gases
More energy than solids
but less than gases
More energy than
solids or liquids

10. Properties Solid Liquid Gas
Shape
Reason: Reason: Reason:
Volume
Reason: Reason: Reason:
Compressibility
Reason: Reason: Reason:
Fixed
Fixed Fixed
Not fixed Not fixed
Not fixed
Cannot be compressed Cannot be compressed Can be compressed
• Particles are held together by
strong forces of attraction.
• Vibrate about fixed positions &
cannot move about freely.
• Particles are held together
by weaker attractive forces
• Not held in fixed positions
• Move freely by sliding over
one another
• Forces of attraction
between particles are very
weak
• Not held in fixed positions
• Move rapidly in any
direction
• Particles are packed very
close to one another
• Particles are packed very
close to one another
• Almost no empty spaces
between particles
• Particles are further
away from one another
• Particles are still packed
quite closely together
• Particles are further
away from one another
• Particles are still packed
quite closely together
• Large space between
particles
• Can be forced to move
closer together
• Large space between
particles
• Can be forced to move
closer together
Relating Properties of Solid, Liquid & Gas
to the Kinetic Particle Theory

11. Changes of State
Is it reversible?

12. SOLID
LIQUID GAS
1. M
ELTING
Changes of State

13. 1. Melting
What happens to the particles of a solid that
is heated until it melts?
As heat energy is supplied to the
solid and converted into kinetic
energy, the particles vibrate faster
about their fixed positions.
When the vibrations of the particles
overcome the attractive forces between
them, they begin to break away from their
fixed positions.
The particles slide over
one another and the
substance is now a liquid.
Heat energy

14. Heating Curve (Melting)
Temperature/o
C
Time/min
A  B: Solid heats up.
The temperature of the solid increases
until it reaches point B, its melting point.
At point B, the solid begins to melt.
B  C: Solid melts.
A mixture of solid and liquid exists here.
During the melting process, the temperature
of the substance remains constant even
though heating continues.
All the heat energy taken in by the particles is
used to overcome the forces of attraction
between particles.
C  D: Liquid heats up.
At point C, all the solid has
melted and the temperature
of the liquid rises as
heating continues.

15. SOLID
LIQUID GAS
2. FREEZING
1. Melting
Changes of State

16. 2. Freezing
Energy is given out by the
particles of the liquid. They lose
kinetic energy and begin to
move more slowly.
When the temperature is low enough, the
particles do not have enough energy to
move freely. Some particles start to settle
into fixed positions.
Finally, all the particles settle into
fixed positions. Particles can only
vibrate about their fixed positions.
The substance is now a solid.
What happens to the particles of a liquid
that is cooled until it freezes?

17. Cooling Curve (Freezing)
Temperature/o
C
Time/min
P – Q: Liquid cools.
The temperature of the liquid drops until it
reaches point Q, the freezing point of
naphthalene. At point Q, the liquid starts to
freeze.
Q – R: liquid freezes.
A mixture of liquid and solid
exists here. During the
freezing process, the
temperature of the
substance remains
constant even though
cooling continues.
R – S: solid cools.
At point R, the substance
has solidified.
The temperature of the
solid continues to drop
as it is cooled.

18. SOLID
LIQUID GAS
3. Evaporation / Boiling
2. Freezing
1. Melting
Changes of State

19. 3. Boiling
As the liquid is heated,
the particles gain
kinetic energy and start
to move faster.
Eventually, the
particles have
enough energy to
overcome the
attractive forces
holding them
together.
They spread far apart and
move rapidly in all
directions. The substance
is now a gas.

20. Heating Curve (Boiling)
Temperature/o
C
Time/min
When a liquid is heated, its
temperature increases till its
boiling point is reached.
Here, it boils and
changes into a vapour.
Temperature remains constant till all
the liquid has boiled off.
Heat energy taken in is used to
overcome forces of attraction
between the particles of the liquid and to
make the particles move further apart.
X
Y
The temperature remains
constant till all the liquid has
boiled off
Z

21. SOLID
LIQUID GAS
3. Evaporation / Boiling
2. Freezing
1. Melting
Changes of State

22. 3. Evaporation
Evaporation occurs because
some particles have
enough energy (more
kinetic energy) to escape
as a gas from the surface
of the liquid.
Volatile liquids are liquids that evaporate quickly at
room temperature. E.g. Petrol and perfumes.

23. Differences between Evaporation & Boiling
Evaporation Boiling
• Occurs at temperatures
below boiling point
• Occurs only at the surface of
the liquid
• Occurs slowly
• Occurs only at boiling point
• Occurs throughout the
liquid
• Occurs rapidly

24. SOLID
LIQUID GAS
4. Condensation
3. Evaporation / Boiling
2. Freezing
1. Melting
4. Sublimation
Changes of State

25. 4. Condensation
• Condensation occurs when a gas is cooled
sufficiently to change into a liquid.

26. Eventually, the
movement of the
particles becomes
slow enough for the
gas to change into
a liquid / move
closer to slide past
one another.
Heat energy is
given out, and the
gas particles lose
energy and move
more slowly as
the temperature
drops.
4. Condensation

27. SOLID
LIQUID GAS
4. Condensation
3. Evaporation / Boiling
2. Freezing
1. Melting
4. Sublimation
5. Condensation
Changes of State

28. 5. Sublimation
Dry ice sublimes
• Sublimation involves changing
solids directly into a gas without
going through the liquid state.
• Examples of substances
undergoing sublimation:
1. Dry ice (Solid carbon
dioxide)
2. Solid Iodine
3. Ammonium Chloride
4. Naphthalene (Moth ball)

29. 5. Sublimation
• Occurs because particle at the surface have enough
energy to break off from the solid and become gas
SOLID GAS
Solid iodine Iodine vapour
A substance sublimes because the forces between
the particles in the liquid state are too weak to
remain in this state.

30. Summary
Mixture of
Solid & Liquid
Mixture of Liquid & Gas
SOLID LIQUID GAS
MELTING POINT BOILING POINT

31. Summary
Heat
Absorbed
(endothermic)
Heat given
out
(Exothermic)
Process
involved
Melting
Boiling
Evaporation
Sublimation
Freezing
Condensation