Changes of State Lab
Grade 7 Science
Your Task
• Every two minutes one student will record the
temperature of the ice or the water on the
large chart, and make a short observation of
the state of the substance.
• You will be doing this while taking notes so
pay careful attention!
Particle Theory of
Matter
Grade 7 Science
What is matter?
• Matter is anything that takes up space and has
mass – so everything around us!
• Matter comes in three main states:
State
Examples
Solids
Liquids
Gases
What is matter?
Fun Fact!
There are two other states of matter:
Plasma and Bose-Einstein condensates
What is the Particle Theory of Matter?
• The Particle Theory of Matter is how scientists
explain how particles stay together as matter,
and how particles behave when matter is in
different states.
• The Particle Theory of Matter is made up of
four main points.
Point 1
All matter is made
up of particles
All matter is made up of particles
• In any state (solid, liquid, gas), every object is
made up of particles too small to see. These
particles are called atoms and molecules.
• These particles are often referred to as “the
building blocks of life”. Think Lego.
• Different substances have different part.
Example:
Tearing Paper
When you tear a
piece of paper into
smaller and smaller
pieces, the
molecules do not
change.
The fact that the
paper tears implies
that it is made up of
smaller particles. If
not, the paper would
not tear.
Point 2
All particles are in
constant motion
All particles are in constant motion
• All particles vibrate, rotate, and move in
straight lines.
• Think about when there’s a class in the
tech room cooking up a delicious storm.
How is that you can smell the food even
upstairs?
• It’s because the particles in the air are
moving!
All particles are in constant motion
• Particles move differently in the different
states of matter.
Solid
- definite size and
shape.
- particles in solids can
only vibrate in one
place.
Liquid
- definite size and
volume, but the shape
can change.
- particles are sliding
around and over each
other. Think: pouring.
Gases
- no particular shape
or size.
- particles move as
much as the space
they are in allows.
- particles can be
compressed.
Point 3
There are spaces
between particles
There are spaces between particles
• The size of the spaces varies with the state of
matter.
• Which state do you think has the most space
between particles? The least?
Solid
- very little space
between the particles
You can’t walk through
a door. The door is
Solid.
Liquid
- particles are
arranged randomly
- large spaces between
particles
You can swim in the
water. There are some
spaces in the Liquid.
Gas
- very large spaces
between the particles
(as much as the space
allows)
You can walk around.
There is enough space
in the air to let you
through.
Point 4
Adding heat causes
particles to move faster
Adding heat causes particles to move faster
• Think of your muscles. Before doing any
aggressive physical activity, you have to warm
up your body or you will pull something.
• When the particles of a solid are heated up,
the particles take that energy and move
around more.
Adding heat causes particles to move faster
Red = taking away heat
Blue = adding heat
Adding heat causes particles to move faster
• What are your observations from the changes
of state lab?
• Do they support or refute this point of the
Particle Theory of Matter?
Dictionary Time!
Melting Point
• The melting point is the
temperature at which a
solid turns into a liquid.
• Example, the melting
point of water (ice) is
around 0 degrees
Celsius.
0o Celsius
Boiling Point
• The boiling point is the
temperature at which a
liquid turns into a gas.
• Example: The boiling
point for water is 100
degrees Celsius.
100o Celsius