Physics and Chemistry UNIT 2
2º ESO IES ÁNGEL DE SAAVEDRA
2. THE STATES OF MATTER
2.1. THE THREE STATES OF MATTER
Every substance can take on several distinct forms called phases or states of aggregation
of matter. Four states of matter are observable in everyday life: solid, liquid, gas, and plasma.
There are several other states (liquid crystal, superfluid, Bose–Einstein condensates…) but these
only occur in extreme situations such as ultracold or ultradense matter.
Substances can move from one phase to another if certain physical conditions, like temperature,
change.
Example:
Each state has different macroscopic1 properties:to
SOLID
LIQUID
Fixed volume and shape
2
Assumes the shape of the
bottom part of the container
they occupy, with a free
surface at the top
GAS
Assumes the shape and
whole volume of its container
Not easily compressible .
Not easily compressible
Easily compressible
Does not flow easily
Flows quite easily
Flows very easily
Both gases and liquids are called fluids due to their capacity to flow.
1
“Macroscopic” It means large enough to be visible to the naked eye.
When you “compress” something, you measure out a certain amount of material and force it into a smaller volume.
2

Copy in your notebook the diagram that shows the macroscopic property of each state and learn
it.

Go to this youtube video and answer the questions at the end of the unit.
https://www.youtube.com/watch?v=U5x2S4iWDm8
Physics and Chemistry UNIT 2
2º ESO IES ÁNGEL DE SAAVEDRA
2.2. THE KINETIC THEORY
The kinetic particle theory explains the properties of the different states of matter. The particles
in solids, liquids and gases have different amounts of energy. They are arranged differently and move in
different ways.
The table below summarises the arrangement and movement of the particles in solids, liquids
and gases, and shows simple diagrams for the arrangement of the particles.
Diagram of particle arrangement and movement
Solids
The table shows some of the properties of solids and why they are like this.
Property
Solids have a fixed shape and cannot flow
Solids cannot be compressed or squashed
Why
The particles cannot move from place to place
The particles are close together and have no space
to move into
Liquids
The table shows some of the properties of liquids and why they are like this.
Property
Liquids flow and take the shape of their container
Liquids cannot be compressed or squashed
Why
The particles can move around each other
The particles are close together and have no space
to move into
Gases
The table shows some of the properties of gases and why they are like this.
Property
Gases flow and completely fill their container
Gases can be compressed or squashed
Why
The particles can move quickly in all directions
The particles are far apart and have space to move
into
Physics and Chemistry UNIT 2

2º ESO IES ÁNGEL DE SAAVEDRA
Draw in your notebook a diagram of particles for solids, liquids and gases according with the
Kinetic theory and describe their properties.
2.3. STATE CHANGES
Substances can exist as a solid, liquid or gas. Converting from one state to another usually
involves heating or cooling.


Heat must be supplied to a substance for it to melt, evaporate or boil. For example, you need to
heat ice to melt it, and you need to heat water to make steam.
Heat must be removed from a substance to condense or freeze it. In other words, the substance
must be cooled down.
Under certain conditions, some solids turn straight into a gas when heated. This process is called
sublimation. A good example is solid carbon dioxide, also called ‘dry ice’. At atmospheric pressure, it
turns straight into gaseous carbon dioxide.
Liquid carbon dioxide can only exist under high pressure, such as in fire extinguishers. Iodine also
sublimes - it turns directly from shiny purple-black crystals to a purple vapour when warmed up.
Changing the pressure
A gas will also liquefy (turn into a liquid) if its pressure is increased enough. This is because the
particles are moved close enough for bonds to form between the particles.
Gas cylinders used for camping stoves and barbecues contain liquefied petroleum gas (LPG)
under high pressure. As soon as the pressure is released, the liquid turns back to a gas.

Draw in your notebook a diagram with the name of the changes of state and learn them.
Questions about the video:

What is matter?

What are the five states of matter that are showed in the video?

Matter needs a __________ ___________temperature to be in Bose Einstein condensate state.

Describe the solid characteristic according to the video and the Kinetic Theory.

Gas particles has _______big space between them and _______ kinetic energy.

Plasma is the _________ ___________ state in the universe.
Physics and Chemistry UNIT 2
2º ESO IES ÁNGEL DE SAAVEDRA
2.4. WORKSHEET. Answer the next question in your notebook:
1.
What are the 3 more common forms of matter on the earth?
a. solid
b. plasma
c. liquid
d. gas
2.
This state of matter has no definite shape or volume.
a. plasma
b. gas
c. liquid
d. solid
3.
A solid is a state of matter that has a definite volume, but not a definite shape.
a. True
b. False
4.
A substance which takes the shape of its container and has a definite volume is a
a. solid
b. liquid
c. gas
d. crystal
5.
Particles of matter that move faster (like in a gas) have more of what?
a. energy
b. mass
c. color
d. weight
6.
True or false? The particles of a gas are packed tightly together.
7.
True or false? Gases are hard to compress.
8.
True or false? Liquids are easy to compress.
9.
The particles in a liquid are
a. closer together than in a solid and further apart in a gas
b. are spaced the same as in solids and gases
c. closer than in gases but further apart in solids
d. none of the above
10.
The process by which liquid changes into a gas is called _________________
11.
When a solid changes to a liquid, what is it called?
12.
When a gas reaches its condensation point, what does it become?
13.
What is it called when a solid changes directly into a gas?
14.
When solids reach their melting points, what do they become?