3. LEARNING
OBJECTIVES
2.1.1 States of matter
Core • State the distinguishing properties of solids,
liquids and gases
2.1.2 Molecular model
Core • Describe qualitatively the molecular structure of
solids, liquids and gases in terms of the arrangement,
separation and motion of the molecules
• Interpret the temperature of a gas in terms of the
motion of its molecules
• Describe qualitatively the pressure of a gas in terms of
the motion of its molecules
• Show an understanding of the random motion of
particles in a suspension as evidence for the kinetic
molecular model of matter
• Describe this motion (sometimes known as Brownian
motion) in terms of random molecular bombardment
Supplement • Relate the properties of solids, liquids and
gases to the forces and distances between molecules and
to the motion of the molecules
Explain pressure in terms of the change of momentum of
the particles striking the walls creating a force
• Show an appreciation that massive particles may be
moved by light, fast- moving molecules
6. How can we know if something is matter or not? Ask yourself:
If it has mass and takes up space… it is matter !!
Can we weigh it on any
scale?
Does it occupy a volume?
If the answer is ‘yes’ then it has MASS
If the answer is ‘yes’ then it takes up SPACE
7. Then...
What do you think
are examples
of non-matter?
Clue: there have to be things that do not have volume or mass.
Volume Mass
8. Emotions: Love, hate, and happiness are feelings.
They don’t have mass or occupy volume.
Memories: Like emotions, these are non-matter.
Dreams: Again, you can’t weigh them on a balance or enclose them in a container.
Vacuum: a vacuum is a place that does not contain any matter.
Energy: Light, heat, kinetic and potential energy, and sound are
non-matter because they don’t have mass.
Time: Time can be measured, but it has no mass and occupies no volume.
Magnetism, gravity ...Forces, in general, are not matter.
Information: Information may be recorded in a physical form,
but it’s really just a concept.
Music: Music is sound, which is a form of energy.
Examples of things that are not matter:
11. Department of Mathematics and Science
The particles in SOLIDS are close
together and vibrate in place.
For this reason:
• A solid has definite shape and
definite volume.
• A solid keeps its shape even
when it moves.
12. Department of Mathematics and Science
The particles in LIQUIDS are not as close as
the particles in solids and move more freely
than particles of solids.
For this reason:
• Liquids have a definite volume.
• Liquids take the shape of their container.
• Liquids can be poured from one container
to another.
13. Department of Mathematics and Science
The particles in GASES move freely in
all directions.
For this reason:
• Gases have no definite size or
shape.
• A gas will fill all the space inside a
container.
• Gases are easily compressed.
14. The carbon dioxide released by the
baking soda and vinegar reaction
spreads out and fills the balloon.
● Empty water bottle
● Balloon
● Small funnel
● 1 Tablespoon baking soda
● 1/2 cup vinegar
Fizzy drinks also contain gas
inside and can blow a balloon.
If you add a fizzy candy you
will even get more gas.
Expansion of gases
experiment:
Experiment time
Materials:
• Gases have no
definite size
or shape.
• A gas will fill
all the space
inside a
container.
With this experiment
we can observe how ...
15. INDEFINITE VOLUME
and INDEFINITE SHAPE
They spread out to fill the
entire space.
The atoms move fast in all
directions. They move
around freely,
DEFINITE VOLUME and
INDEFINITE shape
They take the shape of
their container
The atoms move around
each other.
They move enough to
slide past each other.
DEFINITE VOLUME and
DEFINITE SHAPE
The atoms are very close.
The atoms can only
vibrate.
They move back and forth
in place.
STATES OF MATTER
To summarize:
Definite = fixed
Indefinite = unfixed
16. Matter can change from one state to another if it is
heated or cooled
Let’s see why:
Adding or removing energy
matter can change its state:
17. Matter can change its state if you raise or lower its temperature.
When the temperature increases, matter has more energy.
The extra energy causes the particles to move more.
The atoms move faster.
18. Matter can change its state if you raise or lower its temperature.
When the temperature decreases, matter has less energy.
Less energy causes the particles to vibrate less.
Atoms move more slowly.
Frozen soap bubble
19. Changes of State
Depending on the temperature and pressure
matter can change from one state to another:
Solids
Liquids
Gases
can melt into liquids
can sublimate into gases
can vaporize into gases
can freeze into solids
can condense into liquids
can deposit into solids
Inverse
sublimation
20. When energy is added to
solids, they can turn into
liquids!
What examples can you think of?
Pouring
molten
iron
Melting
chocolate
Popsicle
melted
by the
heat
Melting
crayons
This is called Melting
or Fusion
21. When energy is added to liquids,
they can turn into gases.
What examples can you think of?
This is called Evaporation
The sweat on your skin
gains energy from the
body and evaporates.
Drying clothes under the sun: water is removed
from the clothes because water droplets get
evaporated due to the heat of the sun
Water from your wet hair
evaporates faster due to
the heat of the hairdryer.
Evaporation happens when
some atoms escape from
the liquid and turn into gas.
It happens faster if the liquid is hot.
Liquids from hot
food evaporate
22. When a gas is cooled, it can turn
into a liquid.
What examples can you think of?
This is called Condensation
+
When a gas is cooled, it has
less energy, its particles
move more slowly and come
closer together forming
droplets (a liquid).
It is the reverse of
evaporation
Water vapour hits a cold
surface (The pot lid) and
condensates forming
droplets of liquid water.
Water cycle:
Evaporation
and
Condensation.
23. What has caused
the droplets of water
to appear
on the outside of this glass?
What has caused
the droplets of water
to appear
on the inside of the window?
24. When a liquid is cooled, it can
turn into solid.
What examples can you think of?
This is called Solidification
+
Freezers remove the
heat from the food
until it is frozen.
Pouring the liquid
metal into the mold
Casting metals to make metal pieces
When the liquid metal is
cooled , it solidifies and
finally the solid metal
piece is extracted from
the mold
25. Sometimes matter can change
directly without passing through
the intermediate liquid phase:
from solid to gas
or
from gas to solid
Sublimation
Inverse
sublimation
When it is very cold,
water vapour in the air
changes directly to ice
without first becoming a
liquid.
Mothballs
slowly
disappear
as they turn
into gas
27. Each substance has unique temperature points at which it will boil, freeze, or melt.
Phase changes happen when you reach certain special points.
In the case of water
28. Take a look at these examples:
The melting point of pure gold
is 1.064 ºC
A candle wax becomes solid at
room temperature.
The freezing (solidifying) point of
wax is room temperature.
The boiling point of cooking oil
is about 300 ºC
The freezing point of drinking
alcohol is -114 ºC
29. All liquids can evaporate at any temperature.
Evaporation happens when atoms or molecules
escape from the surface of the liquid and turn
into vapour.
Evaporation is different from boiling
no bubbles are formed bubbles are formed
in the liquid in the liquid
31. Physical properties of Matter
Physical properties of a material are qualities that can be
detected using our five senses or a measuring device.
Some physical properties
are:
● Flexibility
● Hardness
● Solubility
● Electrical conductivity
● Thermal conductivity
……...
Thermometre
Graduated
cylinder
Tape measure Scale
32. Flexibility
It is the ability to bend without breaking
and return to its original shape after bending.
Fibreglass is flexible Metals are rigid
33. Hardness
It is the ability to scratch or resist
being scratched by other materials.
Diamond is harder than talc
Gypsum is softer than quartz
Scientists use Mohs Hardness Scale
to measure a mineral’s hardness.
A material can scratch another material
that is softer than itself.
35. Solubility
It is the ability of one substance to
dissolve into another substance.
Tea dissolves in water Sand doesn’t dissolve in water
Tea is soluble
in water
Sand is insoluble
in water
36. Electrical conductivity
It is the ability of a material to
conduct electricity.
Conductor materials,
like copper,
allow electric current
to pass through them
Insulator
Insulation materials,
like plastic,
don’t allow electric current
to pass through them
37. The plastic
insulates your
fingers from the
electricity flowing
through wires.
Copper
conductor
Plastic
insulation
Electrical wires are
insulated with a
plastic cover
38. Experiment time We can build an electrical
circuit to test electrical
conductivity.
If the bulb lights, the object is a
conductor.
39. Thermal conductivity
Metals are good thermal conductors:
they allow heat to flow easily.
It is the ability of a material to
conduct heat.
Wood, plastic and fabric are
good thermal insulators: they
don’t allow heat to flow easily.
40. Experiment time
Heat conduction
experiment.
Butter. Plastic, wood
and metal spoons
Boil some water
1 2
3
Place the spoons in the water.
Place a slice of butter in each of
the spoons
Wait a few minutes and check
the butter
Which one do you think will melt
first?
or
41. Magnetism It is the ability of a material to be
attracted to a magnet.
Paper clips, made of
steel, are attracted
to a magnet.
They are magnetic.
Wood and glass are not
attracted to magnets.
They are non-magnetic.
42. Transparency It describes how well light passes through
a material.
We can partially see
through it
We cannot see
through it
We can clearly see
through it
Transparent
Translucent
Opaque
43. Elasticity
It is the ability of a material to return
to its original size and shape after
being stretched.
An elastic material returns
to its original shape when the
force stops (after we stretch it).
Rubber band
Plasticine is non-elastic. It doesn’t return
to its original shape after being deformed.
44. Texture It is the property that describes how
the surface of a substance feels.
The surface of
a ceramic bowl
feels smooth
The fur of a cat
feels soft/ fluffy
The surface of the
cement sidewalk
feels rough
45. Match the properties being tested:
1. Does electricity flow when the material is used to complete the circuit?
2. Does the material stretch and then return to its original shape?
3. Does the material heat quite quickly?
4. Is the material attracted to the magnet?
5. Can a penny scratch the material?
6. Does light pass through the material?
7. Does the material bend without breaking?
8. Does the material dissolve in water?
9. How does the material feel when you touch it?
● Elasticity
● Thermal conductivity
● Electrical Conductivity
● Hardness
● Transparency
● Flexibility
● Magnetism
● Solubility
● Texture
