This Changing States of Matter slideshow for middle school students is ideally used to teach students about the various processes that change one state of matter to another. The processes featured are freezing, melting, evaporation, condensation, sublimation, and deposition. Thermal energy and movement of molecules are discussed. To download slideshow or the powerpoint version of this slideshow, visit The Homeschool Daily. Be sure to check out our full line of homeschool curriculum. Thanks for looking!

1. Changing States of
Matter
• What determines a state?
• How does a state of matter
change to a different state?
• What are the different
processes by which matter
changes to a new state?

2. What would it take for one state
of matter to change to
another?

3. An increase or decrease
of thermal energy will
change one state of
matter to another.

4. Thermal energy
(also called heat
energy) is
produced when a
rise in
temperature
causes atoms and
molecules to
move faster and
collide with each
other.

5. When matter changes from one
state to another, it is classified
as either an endothermic or
exothermic change.
HEAT
HEAT
ENDOTHERMIC EXOTHERMIC

6. An endothermic change is the term
used to describe a physical or
chemical change in which thermal
energy increases or is absorbed.
Evaporation
Photosynthesis
Cooking

7. An exothermic change is the
term used to describe a physical
or chemical change in which
energy decreases or is released.
Chemical
Change
Fire
Freezing water
into ice

8. Add or Subtract Energy. . .
When energy is added, particles move faster!
When energy is taken away, particles move
slower!

9. A change of state is the
conversion of a substance from
one physical form to another.

10. If these items were left out in
the sun, what would happen to
each?

11. Since there would be an increase in
thermal energy, these items would
change their state of matter.
Solid
Chocolate
would turn
to liquid
chocolate.
Solid Ice
would turn
to liquid
water.
The ice
cream
would melt
to mush.
The puddle would
evaporate.
The molten steel
would harden to
solid steel.

12. Matter will change its state in these
different processes:
- Melting and Freezing
- Evaporation and Condensation
- Deposition and Sublimation

13. Melting: change of state from a
solid to a liquid
In the process of melting,
thermal energy or heat increases.

14. Freezing: change of state from a
liquid to a solid
In the process of freezing,
thermal energy decreases.

15. Evaporation: change of state
from a liquid to a gas
In the process of evaporation,
thermal energy increases.

16. Condensation: change of state
from a gas to a liquid
In the process of condensation,
thermal energy decreases.

17. Sublimation: change of state
from a solid directly to a gas
In the process of sublimation,
thermal energy increases.
When heated,
ice melts.
However, dry
ice (solid
carbon
dioxide)
sublimates.

18. Deposition: change of state from
a gas to a solid
In the process of deposition,
thermal energy decreases.
When water
vapor turns
into frost on
a window,
this is an
example of
deposition.

19. As a state of matter absorbs
thermal energy, the molecules
within the matter move faster and
spread out.

20. Student Activity
• I need 4 students to volunteer.
• Use masking tape to tape the students together.
• The students represent molecules in matter.
• Notice how the molecules are close together.
They can still move, but not very much.
• What state of matter is represented?

21. Student Activity
• The molecules start to gain energy. The
molecules start to move around.
• The tape is broken.
• The molecules have more energy, what state
of matter are the molecules in now?
• Since there was energy added for the solid to
turn into a liquid, is that an endothermic
change or exothermic?
It is an endothermic change.
Energy had to enter the state of
matter for it to change.

22. Student Activity
• The molecules gain even more energy.
• The molecules start to move even more!
• What state of matter do the molecules
represent now?
• Since there was even more energy added to
change the liquid to a gas, was this an
endothermic change or exothermic?
It is an endothermic change.
Energy had to enter the state of
matter for it to change.

23. Complete your Changing States of
Matter graphic organizer.

24. Changing
States of
Matter
Red = Endothermic
Blue = Exothermic
Solid
Ice
Liquid
Water
Gas
Vapor
Use the word bank
to label the graphic
organizer:
- melting
- freezing
- evaporation
- condensation
- sublimation
- deposition
5.) ________________
6.) ________________
Freezing
Melting

25. Change of
State
Direction Endothermic or
Exothermic
Example
Melting Endothermic
Liquid to Solid
Liquid water
freezes into ice
Evaporation Endothermic
Gas to Liquid
Steam condenses
into liquid water
Sublimation Endothermic
Gas to Solid Vapor turns to
frost on window
Changing States of Matter Table
Complete the table by filling in the blanks.
Solid to Liquid
Ice melting to
water
Freezing Exothermic
Liquid to Gas
Liquid water
evaporating to
vapor
Condensation Exothermic
Solid to gas
Dry Ice
sublimes to
gas
Deposition Exothermic

26. To learn more about matter, visit our
States of Matter Printable & Activities
post under our Science Units & Activities.

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a school tool you can use. Please feel free to use this activity for
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Marie