2. Learning Outcomes
• At the end of the lesson, the students should be
able to:
– 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
3. States of Matter
• Matter can exist as a solid, a liquid or a
gas.
• Kinetic particle theory states that
– all matter is made up of tiny particles and
– that these particles are in constant random
motion.
4. Comparing the 3 states
Property
Solid
Liquid
Gas
Shape
Fixed
Not fixed
Not fixed
Volume
Fixed
Fixed
Not fixed
Cannot be
compressed
Cannot be
compressed
Can be
compressed
Strong
Weaker than
that in solid
weak
Compressibility
Forces of
attraction
between
particles
5. Comparing the 3 states
Property
Solid
Liquid
Gas
Arrangement
of particles
closely
packed in
orderly
manner
closely
packed in
random order
far apart
6. Comparing the 3 states
Property
Movement of
particles
Solid
Liquid
cannot move, free to move
vibrates and
within the
rotates about
liquid,
their fixed
vibrates and
position
slides over
one another
Gas
free to move,
move rapidly
in any
direction
7. Changes in States of Matter
• The physical state of a substance
depends on the temperature and pressure
of the surroundings.
• For example
– At room temperature (25 oC), water is in the
liquid state.
– At -10 oC, water is in the solid state.
8. Changes in State
• Heat is a form of energy.
• When matter is heated, the particles
absorb energy.
• When matter is cooled, the particles lose
energy.
• the heat taken in or given out causes the
kinetic energy of the particles to change.
• Hence, the substance changes it state.
9. Changes in States of Matter
condense
melt
boil
condense
freeze
sublime
10. Changes in States of Matter
Melting
Physical
change
Energy
change
Boiling
Freezing
Condensation
Sublimation
Solid to
liquid
liquid to
gas
liquid to
solid
gas to
liquid
solid to
gas
Energy
Energy
Energy
Energy
Energy
absorbed absorbed given out given out absorbed
11. Changes in States of Matter
• What happens during melting
– particles gain energy,
– particles vibrate faster,
– particles overcome attractive forces between
them,
– particles break away from their fixed positions
12. Changes in States of Matter
• What happens during boiling
– particles gain kinetic energy,
– particles move faster,
– particles overcome forces holding them
together,
– particles spread far apart,
– particles move rapidly in all directions
13. Changes in States of Matter
• What happens during freezing
– particles lose kinetic energy,
– particles move more slowly until they no
longer have enough energy to move about
freely,
– particles settle into fixed position
14. Changes in States of Matter
• What happens during condensation
– particles lose energy,
– particles move more slowly,
– becomes a liquid
15. Sublimation
• Particles at the surface of the solid have
enough energy to break away from the
solid and escape as a gas
16. Changes in States of Matter
Melting
Temp at
which
change
occurs
Boiling
melting
point
boiling
point
Freezing Condensation
Freezing
point
-
17. Wake Up Call 1
1. When water vapour condenses to water, the
particles in the vapour
A
gains energy.
B
decrease in density
C
move closer to each other
D
mover further apart from each other.
Answer: C
18. Wake Up Call 1
1.
Three substances have the following properties:
X: melts at -180 oC and boils at -167 oC
Y: has shiny crystalline surface at r.t.p
Z: can flow and take the shape of container at rtp; has boiling
point of 160 oC
What is the state of each substance at room temperature and
pressure?
X
Y
Z
A
Gas
Solid
Liquid
B
Gas
Liquid
Liquid
C
Liquid
Solid
Solid
D
Gas
Liquid
Solid
Answer: A
19. Wake Up Call 1
3 (a)
For the following substances state the physical state
(solid, liquid or gaseous) they are in at a temperature of 1500 oC.
Substance
Melting Point / oC
Boiling Point / oC
Copper
1084
2562
Calcium
842
1484
Iron
1538
3134
Gold
1064
2856
Physical State
20. Wake Up Call 1
b)
Hence draw and describe the arrangement and
movement of particles of copper, calcium and iron at
the temperature of 1000 oC.
(i) Copper
Arrangement:
–
closely packed in orderly
manner
Movement:
–
cannot move, vibrates and
rotates about their fixed
position
(ii) Calcium
Arrangement
– closely packed in random
order
Movement
– free to move within the liquid,
vibrates and slides over one
another
21. Temperature Changes
• When matter is heated
energy causes
temperature to increase.
• Temperature stops
increasing at melting /
boiling points.
• Particles absorb the heat
energy to vibrate faster
and move further apart.
• Matter changes state.
Figure showing the heating curve
of water
