The states of matter

1. Chapter 8
The states of matter

2. What is matter?
Any thing around us that has:
Mass
(Amount of
material in a
substance)
Volume
(Amount of space
and object takes)

3. Examples for matter:
 1)Solid
 2)Liquid
 3)Gas

4. A solid:
 Has definite mass.
 Definite shape.
 It does not flow and it is hard to be
compressed it

5. A liquid:
 Has a definite mass.
 It’s volume does not change .
 It’s hard to be compressed but it flows
easily.
 The shape of the liquid changes as it
takes the shape of the container holding
it.

6. A gas:
 Has a definite mass.
 Its volume vary and it takes the shape of
the container holding it.
 It flows easily and it can be compressed.

7.  Select one state of matter and
imagine that it has been removed
from the world.
List things that could not exist if it
is absent.

8.  2000 years ago a Greek thinker
named “Democritus” said that the
smallest particle that cannot be
divided is called an “Atom”
 The word Atom means: Indivisible.

9. The particle theory of matter
 It stated that matter is made from particles.
 The particles are so tiny that they cannot be
seen by naked eyes.
 Different substances are made from different
particles have different sizes.
 The particles are atoms and molecules.

10. Elements:
 Either made of one kind of atom called :
Molecule.
Example 1:Oxygen
Example 2:Hydrogen
Or different kinds of atoms called :Compound
Example: Water
o o
H H
H Ho

11. The particles in solids
 There is a strong forces hold the
particles together in 3-dimensional
structure.
 In many solids, the particles form an
arrangement called lattice.
 The particles in all solids just vibrate in
its own position.

12. The particles in liquids:
 Why do liquids flow but solids do
not?
 The forces that hold the particles
together are weaker than in solids.
 The particles in a liquid can change
position by sliding over each other.

13. The particles in gases:
 The forces of attraction between the
particles are very weak and the
particles can move away from each
others in all directions.
 When they hit each others or the wall of
the container they bounce and change
their direction.

14. Physical change:
 It is a reversible kind of change in state of
matter by heating or cooling.

15. Melting
 When a solid is heated it loses its shape and
starts to flow.
 The temperature at which melting takes place
is called : Melting point

16. Examples:

17. The particle theory:
 When a solid is heated , the heat
provides the particles with more energy.
 The energy makes the particles vibrate
strongly and push each other and the
solid expand.
 If the solid is heated more the energy
makes the particles vibrate more
strongly and this causes the particles to
slide over each other and become a
liquid.

18.  N.B : During the time from solid starts to
melt until it completely change to liquid,
its temperature does not increase .All
the heat energy is used to separate the
particles so that they can flow over one
another.

19. Freezing
 It is the reverse of melting.
 It is the change from liquid to solid .
 The temperature at which this takes
place is called: Freezing point.

20. - when the particles are cooled down they
lose energy so they cannot slide over
each others . They start to vibrate in their
own position in the lattice .
The liquid become a solid.

21. Evaporation
When the liquid is heated the particles start to
gain heat and move faster leading to the gas
escaping from the surface of the liquid.

22. Boiling
 When a liquid reaches a certain temperature,
it forms a gas inside it . The gas makes
bubbles, which rise to the surface and burst
into the air . This is called boiling
 The temperature at which this takes place is
called : Boiling point.
 If the boiling liquid is heated more strongly, its
temperature does not rise but it boils more
quickly.

23. Graph for boiling point of a liquid

24. Particle theory for boiling
 When a liquid is heated, all the particles
receive more energy and move
quickly. The fastest moving particles
escape from the liquid surface and form
gas.

25. Condensation
 Results as cooling down of gas to
change to liquid.

26. The particle theory for condensation
 The particles losses energy when they
are cooled so they can no longer
bounce off each other when they meet.
 The particles now slide over each other
and form a liquid.

27. Sublimation
 A few substances can change from a
solid to gas , or from gas to solid
directly.
 Example: solid carbon dioxide (dry
ice).

28. Change between states of matter

29. Dissolving
Copper sulfate dissolves in water to form cear blue
solution

30.  When substance dissolves in a liquid it
forms solution.
 The liquid is called solvent and the solid
that dissolves in it is called solute.

31. The particle theory for dissolving
 There are small gaps between the
particles in a liquid. When a substance
dissolves in a liquid, its particles spread
out and fill the gaps.