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Module Six: Signs of a Chemical Change
Teacher Notes
Welcome to the sixth and final module of our series! This series of modules is intended to
help Grade 5 teachers introduce ideas about models and about the particulate nature of
matter to their students. Module 6 begins with asking children to recall what they have
already learned about chemical change in the previous module.
We assume that you have already involved your students in classroom experiences and
activities that are focused on chemical change and that they have heard the term
‘chemical change’. This module focuses on the clues we look for indicating a chemical
change has occurred. Specifically, the module illustrates the following clues: We can
recognize chemical changes if we look for the correct scientific clues: a) light, heat or
sound is given off, b) a change in odour, c) a change in colour, d) a gas is created, or
e) a solid forms.
Note: The script for the module is included at the end of these Teacher Notes.
Links Between Module Six and the Alberta Elementary Science Program
As you teach the expectations that are listed for Classroom Chemistry in the Alberta
Elementary Science Program, your students will be encountering examples of solids,
liquids, and gases. The properties of solids and liquids and gases can be explained by
referring to the arrangement and movement of the small, unseen particles that comprise
matter. Program expectations also include ideas about chemical change – a change in
which small, unseen particles break apart and join together in new ways to form new
substances and the clues that indicate a chemical change. Several clues can be used to
help identify whether a chemical change has occurred.
Tips for using Module Six with your Grade 5 Class
Note: If you want to retain a record of your students’ thinking about the ideas in this
module, please photocopy the worksheet included in these Teacher Notes and distribute
the worksheet prior to beginning viewing.
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Progress through the module using the forward arrow.
If necessary, use the back arrow to return to a previous page.
While reading questions, keep the cursor outside the question box.
Discuss possible answers and consider reasons for your answers.
Roll the cursor back over the question to reveal an answer.
At anytime you can click on Home to return to the beginning.
Big Ideas (Concepts) Featured in Module Six – Signs of a Chemical Change
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A model (e.g., a picture, an animation, a scale model) is a representation of an
object, an event, or an idea.
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All models have strength and limitations; models are ‘good enough’ for
explaining some ideas about the real thing.
All matter is comprised of small, unseen particles that are in constant motion (yes,
even solids!).
Small, unseen particles make up everything in our world and in the universe.
Solids feel hard and keep their shape. Liquids are able to flow and take the shape
of their container. Gases can spread out in all directions.
The properties of solids, liquids, and gases can be explained by thinking about the
arrangement and movement of small, unseen particles.
The small, unseen particles in a solid hold tightly to each other, and vibrate. The
small, unseen particles in a gas are very far apart and do not hold onto each other.
The small, unseen particles in a liquid hold less tightly than the solid, as a result
they move freely past one another.
Physical change is when matter changes state. When matter changes state (for
example, changing from a liquid to a solid), the particles that make up that matter
behave differently. Even though the particles behave differently, no new
substances are formed.
Chemical change is when a new substance is created. When small, unseen
particles break apart and then join together in different ways, new substances are
formed. The new substances are different than the starting substances.
Clues that indicate a chemical change has occurred include: a) light, heat or
sound is given off, b) a change in odour, c) a change in colour, d) a gas is
created, or e) a solid forms.
Background Information about the Particle Nature of Matter and Chemical Change
A basic understanding of chemistry is necessary in order to understand our world around
us. The study of chemistry includes:
1) the composition of matter (matter is made up of small unseen particles called
atoms).
2) the observable properties of matter (mass, odor, color, temperature, solubility,
etc.).
3) how matter can be transformed (either physically or chemically).
We use models to help us explain our observations about the world of matter. Key
features of the particle nature of matter are:
1) all matter is comprised of small, unseen particles that are in constant motion (yes,
even solids!).
2) there are attractive forces between small, unseen particles.
3) there are empty spaces between the small, unseen particles (e.g. there is empty
space between each and every water molecule).
Chemical change involves particles breaking and apart and then joining together in new
ways to form new substances. During a chemical change, mass is conserved (same
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amount of matter at the beginning of the change as there is at the end – no unseen
particles are created or destroyed). Common examples of chemical change include
rusting nails, baking cookies, cooking eggs, and the variety of changes that occur within
your body as you digest food.
Chemical reactions are often accompanied by the absorption or release of energy, color
changes, changes in odour, changes in state (a solid forms), or a gas is created. Chemical
reactions occur at different rates (hydrogen gas will react explosively in the presence of
oxygen, while iron reacts very slowly with oxygen). Gasoline reacts (burns) quickly with
oxygen in a car engine, but needs a spark to occur.
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Module 6: Signs of a Chemical Change
Student Worksheet
Names: _________________________________________________________________
1. Talk with another student and write down three more examples of chemical change.
a) _____________________________________________________________________
b) _____________________________________________________________________
c) _____________________________________________________________________
2. Talk with another student and write down some clues you think scientists look for to
know when a chemical change has happened.
_____________________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
3. Making Pancakes: What clue do you see?
Talk with another student and write down the clue you think this picture (pancakes) is
showing.
_______________________________________________________________________
_______________________________________________________________________
4. Talk with another student and write down another example of a gas being created as a
result of a chemical change.
_______________________________________________________________________
_______________________________________________________________________
5. Sparklers: What clue do you see?
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Talk with another student and write down what clues you think this picture (sparklers) is
showing.
_______________________________________________________________________
______________________________________________________________________
6. Rotting Food: What clue do you see?
Talk with another student and write down what clue you think this picture (rotting food)
is showing.
________________________________________________________________________
________________________________________________________________________
7. Talk with another student and write down a chemical change that causes a change in
odour.
________________________________________________________________________
________________________________________________________________________
8. Rusting Nails: What clue do you see?
Talk with another student and write down what clue you think this picture (rusting nails)
is showing.
________________________________________________________________________
________________________________________________________________________
9. Talk with another student and write down another example of a chemical change that
causes a change in colour.
________________________________________________________________________
________________________________________________________________________
10. Cooking an Egg: What clue do you see?
Talk with another student and write down what clue you think this picture (egg cooking)
is showing.
________________________________________________________________________
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________________________________________________________________________
11. Talk with another student and write down an example of another chemical change
that causes a change in state.
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
12. Talk with another student and write down why lighting a match would be an example
of a chemical change. Try to use the clues of chemical change and try to refer to small,
unseen particles in your answer.
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
13. Talk with another student and write down why adding vinegar to baking soda would
be an example of a chemical change. Try to use the clues of chemical change and try to
refer to small, unseen particles in your answer.
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
14. Talk with another student and write down why breaking a glow stick would be an
example of a chemical change. Try to use the clues of chemical change and try to refer to
small, unseen particles in your answer.
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
15. Think about what you have learned from matching the video with the according
picture:
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Draw an arrow to show which video you first matched with the lit match.
Why did you choose this video for the lit match? ______________________________
______________________________________________________________________
______________________________________________________________________
Draw an arrow to show which video you first matched with the boiling kettle.
Why did you choose this video for the boiling kettle? ___________________________
______________________________________________________________________
______________________________________________________________________
_______________________________________________________________________
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Module 6: Signs of a Chemical Change
Module Script
As you work through this lesson, pay attention to the questions. After trying to come up
with answers on your own, you can roll over each question with your mouse to see if you
are right. To listen to the text, click the play button.
Review of Chemical Change
Chemical changes involve small, unseen particles that break apart and then join together
in different ways to form new substances.
Making and baking cookies and cooking an egg are examples of chemical change.
Talk with another student and write down three more examples of chemical change.
Looking for Clues of a Chemical Change
We can recognize a chemical change if we look for the correct scientific clues. Talk with
another student and write down some clues you think scientists look for to know when a
chemical change has happened.
Clue #1: A Gas Is Created
Making Pancakes: What clue do you see?
Talk with another student and write down the clue you think this picture is showing.
Have you ever cooked a pancake, and noticed the bubbles that come up through the
batter? Those bubbles are a result of a chemical change that happens in the batter. The
creation of a gas (a new substance) is one of the clues that indicates a chemical change
has occurred.
Talk with another student and write down another example of a gas being created as a
result of a chemical change.
Sparklers: What clue do you see?
Talk with another student and write down what clues you think this picture is showing.
Clue #2: Light, Heat or Sound is Given Off
Have you ever seen a sparkler when it is lit? A sparkler gives off a bright light, as well as
some heat and sound. These three clues of a chemical change do not always happen at
the same time.
Rotting Food: What clue do you see?
Talk with another student and write down what clue you think this picture is showing.
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Clue #3: Change in Odour
Have you ever forgotten a lunch in your desk? Or left milk outside of the fridge for a
long time? When this happens, we notice a very strong unpleasant smell. The apple did
not smell bad when you first had your lunch so why does it smell bad now? This change
in odour is a clue that indicates a chemical change has occurred.
Do scientists use odour to detect chemical change? Yes, but sometimes these odours can
be harmful.
Talk with another student and write down a chemical change that causes a change in
odour.
Rusting Nails: What clue do you see?
Talk with another student and write down what clue you think this picture is showing.
Clue #4: A Change in Colour
Have you ever seen old nails that have been left outside? When some nails are left
outside their silver gray metal will change to a reddish brown rust. This change in colour
is a clue that indicates a chemical change has occurred.
Talk with another student and write down another example of a chemical change that
causes a change in colour.
Cooking an Egg: What clue do you see?
Talk with another student and write down what clue you think this picture is showing.
Clue #5: A Solid Forms
Have you ever watched a cooking egg? When an egg is cooking the whites go from a
colorless liquid to a white solid. This change may look like a physical change but it is
really a chemical change! How do we know? We know because the small, unseen
particles that make up the egg white have formed a new substance.
Talk with another student and write down an example of another chemical change that
causes a change in state.
Conclusion
We can recognize chemical changes if we look for the correct scientific clues:
• a gas is created
• a solid forms
• a change in odour
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• a change in colour
• light, heat or sound is given off
Remember that we can use a variety of ‘good enough’ models to explain that chemical
changes involve small, unseen particles that break apart and join together in different
ways to form new substances.
What have you learned?
Talk with another student and write down why lighting a match would be an example of a
chemical change. Try to use the clues of chemical change and try to refer to small,
unseen particles in your answer.
Talk with another student and write down why adding vinegar to baking soda would be
an example of a chemical change. Try to use the clues of chemical change and try to
refer to small, unseen particles in your answer.
Talk with another student and write down why breaking a glow stick would be an
example of a chemical change. Try to use the clues of chemical change and try to refer to
small, unseen particles in your answer.
Try to match the video with the correct picture. That's right. Good job matching the
small, unseen particle models with their matching situation. Try again. If you need to,
go back through the module and review the differences between a physical and chemical
change. Congratulations! You have correctly matched all of the videos.
The picture on the right is showing the physical change of water boiling into steam.
The picture on the left is showing the many chemical changes that happen when lighting
a match.
Looking Ahead
This is the end of our series of chemistry modules. We hope you enjoyed thinking about
the clues that help scientists know a chemical change has occurred and have learned more
about the small, unseen particles that make up all matter.
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Acknowledgements
Teacher Notes for this module were written by Dr. Brenda Gustafson (University of
Alberta), Ms. Shannon Gentilini (Edmonton Public Schools), Ms. Sandy Martinell-Jones
(Pembina Hills Regional Division).
Funding support from CRYSTAL-Alberta is gratefully acknowledged.
Project Team Members: Dr. Brenda Gustafson (University of Alberta), Dr. Peter Mahaffy
(King’s University College), Dr. Brian Martin (King’s University College), Ms. Shannon
Gentilini (Edmonton Public Schools), Ms. Amanda Thompson (King’s University
College), Ms. Naomi Mahaffy (King’s University College), and Mr. David Dykstra
(King’s University College).
2009