1. The Particulate Nature of Matter
Syllabus objectives :
Describe the solid, liquid and gaseous states of matter and explain their interconversion in terms of the kinetic particle theory and of the energy changes involved.
Describe and explain evidence for the movement of particles in liquid and gases.

2. Matter - a Particle Explanation
Matter is anything that occupies space and has mass.
Matter is made up of small particles - Democritus
By convention there is color,
by convention sweetness,
by convention bitterness,
but in reality there are atoms and space.
-Democritus BC

3. The Kinetic Particle Theory
The Kinetic Particle theory of matter states that
all matter is made up of tiny particles;
all particles are in constant random motion

4. Particulate Nature of Matter - Evidence
From Diffusion experiments…
When a few drops of bromine are placed into a gas jar of air, the red-brown bromine vapour spreads slowly upwards until the whole jar is filled with a uniform brown vapour.

5. Particulate Nature of Matter - Evidence
From Diffusion experiments…
…observations can be explained if we accept the idea that the substances are made up of small particles in constant motion.

6. Particulate Nature of Matter - Evidence
From Diffusion experiments…
..and during diffusion, the bromine particles move into the spaces between the air particles while the air particles move into the spaces between the bromine particles..

7. Particulate Nature of Matter - Evidence
From changes in volume - mixing water & alcohol
…observation can be explained if we agree that water and ethanol are made of particles.
There are empty spaces between the ethanol particles. The water particles move into these spaces.
50 cm3 of water mixed with
50 cm3 of alcohol gives
98 cm3 of mixture

8. Particulate Nature of Matter - Evidence
From changes in volume - mixing water & alcohol
…observation can be explained if we agree that water and ethanol are made of particles.
There are spaces between the ethanol particles. The water particles move into these spaces.
By convention there is color,
by convention sweetness,
by convention bitterness,
but in reality
there are atoms and space.
-Democritus BC

9. Particulate Nature of Matter - Evidence
From changes of state

10. Particulate Nature of Matter - Evidence
Others - dissolving, fusing of metals

11. The Particles of Matter
Atoms
Molecules
Ions

12. The 3 States of Matter    Property solid liquid gas Definite mass
  
Definite shape
  
Definite volume
  

13. The Kinetic Particle Theory
The Kinetic Particle theory of matter states that
all matter is made up of tiny particles;
all particles are in constant random motion

14. The 3 States of Matter

15. The 3 States of Matter Property solid liquid gas Packing of particles
closely packed far apart
Arrangement of
particles
Orderly Not orderly Not orderly
vibrate and rotate about fixed positions
vibrate and
slide over one
another
move rapidly and at
random in any
direction
Movement of
particles
Attractive forces
between particles
very strong less strong almost no

16. The Solid State Property Explanation
particles cannot move freely; can only vibrate about fixed positions
Definite shape
Definite volume
Cannot be compresssed
Particles are packed very closely together

17. The Liquid State Property Explanation No definite shape
particles can slide over one another
Cannot be compresssed; has fixed volume
Particles are packed close together

18. The Gaseous State Property Explanation No definite shape or volume
particles can move about rapidly and randomly in any direction as forces between particles are weak
Can be compresssed
Particles are far apart, with a lot of empty space between them

19. Changes of State GAS boiling condensation sublimation condensation
melting
SOLID
LIQUID
freezing

20. Melting - in terms of Kinetic Particle Theory
When a solid is heated, heat energy is absorbed. This causes the particles to gain kinetic energy and to vibrate faster.
At a certain temperature (melting point, the vibrations become so violent that the particles are able to overcome some of the attractive forces between them and break away from each other.
The solid then becomes a liquid. Melting occurs.

21. Freezing - in terms of Kinetic Particle Theory
When a liquid is cooled, heat energy is released. This causes the particles to lose kinetic energy and to vibrate slower.
At a certain temperature (freezing point, the vibrations become so slow that the particles are unable to overcome the attractive forces between them and are drawn towards each other in orderly and fixed positions.
The liquid then becomes a solid. Freezing occurs.

22. Boiling - in terms of Kinetic Particle Theory
When a liquid is heated, heat energy is absorbed. This causes the particles to gain kinetic energy and move faster.
At a certain temperature boiling point), the vibrations become so violent that the particles throughout the liquid are able to break away from the forces holding them together.
The liquid then becomes a gas. Boiling occurs.

23. Sublimation - in terms of Kinetic Particle Theory
When the solid is heated, heat energy is absorbed. Particles gain kinetic energy and move faster.
At a certain temperature the vibrations become so violent that the particles break free completely from each other, and move randomly.
The solid then becomes a gas directly. Sublimation occurs.

24. temperature remains constant. Why?
Heating Curve
temperature (ºC)
melting starts
temperature remains constant. Why?
melting completes
time from start (min)
melting point
SOLID
SOLID + LIQUID
LIQUID
Heat energy absorbed by the particles is used to overcome the forces of attraction holding the particles together in their fixed positions.

25. Cooling Curve LIQUID SOLID LIQUID + SOLID
Heat loss due to cooling is exactly balanced by the heat energy liberated as the particles attract one another to form a solid.
temperature remains constant. Why?
freezing completes
freezing starts
freezing point (=melting point) for pure substances
SOLID
LIQUID + SOLID
LIQUID
temperature (ºC)
time from start (min)

26. Evaporation vs Boiling
Similarity : Both involve the change of state from liquid to gas.
Differences :
Boiling
Evaporation
Takes place at boiling point of the liquid
Takes place at any temperature below
takes place throughout the liquid
takes place at the surface of the liquid
very fast process
very slow process

27. Predicting physical states
Substance X has m.p. -460C and b.p. 1670C.
What is its physical state at
(i) room temperature (ii) -100C (iii) -500C ?
LIQUID
GAS
SOLID
- 460C
s  l
250C
1670C
l  g