A presentation that provides basic knowledge of the Kinetic Model of Matter. It sheds light on introductory concepts about the arrangement and motion of particles in each of the 3 states of matter. The presentation clearly and graphically explains the processes of changes in states of matter in a straightforward tone using simple language. A brief overview of the major gas laws is also given. Suggested for the IGCSE and O Level Physics and Chemistry lessons.

1. THE KINETIC MODEL OF
MATTER

2. What is the Kinetic Model?
• A model represents a system in order to help us understand it.
• Kinetic model represents the constituent particles of matter
• Aids in understanding matter’s behavior, and properties in the
different states.

3. The Kinetic Model of Matter
• Matter is made up of tiny particles, atoms or molecules
that are always moving.
• Matter can exist in three different states: Solid, Liquid
and Gas.
• Arrangement and motion of particles determines
matter’s behavior in each state.

4. The States of Matter
Matter can exist as a solid, liquid or a gas. The behavior of a substance in
each state is different due to variations in the arrangement and motion of
particles in each state.

5. SOLIDS
• Fixed shape
• Fixed volume
• Incompressible
• Particles packed closely together
• Particles held in a regular arrangement
by strong attractive forces
• Particles vibrate in fixed positions
• Cannot change their positions

6. LIQUIDS
• Fixed volume
• No fixed shape. Take the shape of their
container.
• Slightly compressible
• Particles held close together by attractive
forces of moderate strength
• Particles vibrate but move freely and
randomly within bulk of the liquid
• Particles can slide past each other

7. GASES
• No fixed volume. Volume is same as
volume of container.
• Take the shape of their container.
• Easily compressible.
• Particles far apart from one another.
• Weak or negligible forces of attraction.
• Particles move freely and randomly at high
speeds.
• Particles collide with each other and walls
of their container.

8. Attractive Forces between Particles
• Attractive forces hold particles together.
• The closer the particles together, the stronger the forces between them.
• Forces are strongest between particles in solids.
• Forces are weaker between particles in liquids.
• Very weak or no attractive forces are present between particles in a gas.

9. Brownian Motion as
Supportive Evidence for the
Kinetic Model
The movement of smoke grains viewed under a microscope in an
illuminated chamber serves as supportive evidence for what the kinetic
model of matter theorizes about the motion of particles.

10. Brownian Motion
Random motion of microscopic particles
suspended in a fluid.
• Smoke inside a cell is viewed through a microscope.
• The cell is illuminated using a lamp.
• Jerky and erratic path of smoke particles is observed.
• Random movement is caused by repeated and frequent collisions with
surrounding, INVISIBLE particles of the air.

11. Experimental Setup Observation

12. Changes in the States of
Matter
Changes in the states of substances can be explained by the kinetic model
by carefully considering the attractive forces between particles and the
changes in their arrangement and motion.

13. Changes in State

14. Melting
• Melting is the change in state from solid to liquid.
• Occurs at a fixed temperature for a pure substance called the melting
point.
• Melting point of pure ice is 0℃.
• Upon heating the particles in the solid gain energy
and start vibrating faster.
• At the melting point, they have energy to overcome
some of the bonds holding them together and
therefore.
• Particles break away from each other and lose their
regular arrangement. They are then able to move
freely and slide past one another. The solid has
melted into a liquid.

16. Boiling
Change in state from liquid to gas at a fixed temperature, called the boiling
point for a pure substance. Boiling occurs throughout the liquid. Bubbles of
gas start forming deep inside the liquid.
• Boiling point of pure water is 100℃.
• Upon heating, particles in the liquid gain energy and
start moving faster.
• At the boiling point, they have enough energy to
overcome almost all of the attractive forces between
them.
• The particles move far apart from one another and
move randomly at high speeds. The liquid has boiled
into a gas.

17. Boiling

18. Evaporation
• Change in state of a substance from a liquid to gas below its boiling point.
• Occurs at the surface of the liquid.
• Occurs at no fixed temperature.
• Some particles in a liquid have higher energy than others.
• These particles have enough energy to escape from the surface of the
liquid, as a gas.
• Remaining particles are those with lower energy.

19. Evaporation

20. Explaining the Cooling Effect of Evaporation
• Temperature is a measure of the average kinetic energy per
particle of a substance.
• During evaporation, particles with higher energy escape.
• Average kinetic energy of he particles of the substance
decreases.

21. Explaining Observations About Evaporation
• Rate of evaporation increases with temperature.
• Rate of evaporation increases with surface area.
• Evaporation occurs slowly under humid conditions.
Particles of water vapor can enter the liquid from the air.
• Evaporation rate increases under windy conditions.
Wind carries evaporated particles away from the liquid. As a result, none of
them can fall back into the liquid.

22. Condensation and Freezing
• Upon cooling, particles of a gas lose energy and slow down.
• Attractive forces grow stronger and pull the particles close together
eventually, forming a liquid. This is condensation.
• If the liquid is further cooled, the particles gain a regular arrangement as
attractions strengthen. This forms a solid. Freezing point is the same as
melting point.

23. Heating and Cooling Curves for Water

24. The Behavior of Gases
The kinetic model of matter helps us understand, explain and correlate many
different properties of gases such as their pressure, volume and
temperature.

25. Gases and Pressure
• Gases have no fixed volume or shape.
• They expand to fill their container.
• Particles are moving randomly at high
speeds and are far apart from one another.
• Particles collide with the walls of the
container.
• Large number of particles, high speeds,
frequent collisions = high net pressure

26. Gay-Lussac’s Law of Gases
• For a gas with a fixed volume, the pressure of the gas is directly
proportional to its temperature. Container has rigid walls.
𝑝𝑟𝑒𝑠𝑠𝑢𝑟𝑒 ∝ 𝑡𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒
• At higher temperature, particles have more energy.
• They collide at higher speeds and exert greater force.
𝑝1
𝑇1
=
𝑝2
𝑇2
Where p is the Pressure and T is the temperature
in degrees Kelvin.

27. Gas Pressure and Temperature

28. Charle’s Law of Gases
• The volume of a gas is directly proportional to its temperature, provided
that its pressure remains constant.
• At higher temperature, the particles have higher energy.
• The pressure increases causing the container to expand. Container does
not have rigid walls.
𝑉𝑜𝑙𝑢𝑚𝑒 ∝ 𝑇𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒
𝑉1
𝑇1
=
𝑉2
𝑇2
Where V is the volume and T is the
temperature in degrees Kelvin.

29. Gas Volume and Temperature

30. Boyle’s Law of Gases
• Provided that the temperature of the gas remains constant, its pressure will be inversely
proportional to is volume.
𝑃𝑟𝑒𝑠𝑠𝑢𝑟𝑒 ∝
1
𝑉𝑜𝑙𝑢𝑚𝑒
• If the volume of the gas is doubled, there are only half as many collisions on every meter
square of the container’s walls. Therefore, pressure halves.
• If volume is halved, twice as many collisions on every square meter of the container’s
walls will occur. Therefore, pressure doubles.
𝑝1 𝑉1 = 𝑝2 𝑉2
⇒ 𝑝𝑉 = 𝑐𝑜𝑛𝑠𝑡𝑎𝑛𝑡

31. Gas Pressure and Volume

32. KEY POINTS
• Matter is made up of tiny, moving particles.
• Matter can exist in three states – SOLIDS, LIQUIDS and GASES.
• Arrangement and motion of particles is different in each state.
• Brownian motion is the random movement of particles suspended in
a fluid and occurs as a result of frequen collisions with the fluid
particles. This serves as evidence for the kinetic model.

33. KEY
POINTS

34. KEY POINTS

35. THANK YOU!