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Module Five: Chemical Change
Teacher Notes
Welcome to the fifth 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 5 begins with asking children to recall what they have already
learned about physical change and how small, unseen particles behave and are arranged
during physical changes.
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 defines chemical change and provides additional
examples of chemical change. Chemical change is contrasted with physical change to
show the differences between the two changes. Models of small, unseen particles are
used to illustrate what occurs during a chemical change. Important to this module is to
help students understand that chemical change involves particles breaking apart and
joining together in new ways to form new substances.
Note: The script for the module is included at the end of these Teacher Notes.
Links Between Module Five 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.
Tips for using Module Five 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 Five – 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.
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
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
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rusting nails, baking cookies, cooking eggs, and the variety of changes that occur within
your body as you digest food.
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Module 5: Chemical Change
Student Worksheet
Names: _________________________________________________________________
1. Talk with another student and write down three different examples of physical change.
a) _____________________________________________________________________
b) _____________________________________________________________________
c) _____________________________________________________________________
d) _____________________________________________________________________
e) _____________________________________________________________________
2. Talk with another student and write down three examples of chemical change that are
happening in your classroom.
a) _____________________________________________________________________
b) _____________________________________________________________________
c) _____________________________________________________________________
3. Talk with another student and write down why you think cooking an egg might be a
chemical change or a physical change.
We think is a _______________________ change because _______________________
_______________________________________________________________________
_______________________________________________________________________
4. Look at the picture below of A Good Enough Model of a Chemical Change:
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What are the ways that the small, unseen particles are changing? ________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
How is this similar to the sky divers?
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
How is this different from the sky divers? _____________________________________
_______________________________________________________________________
_______________________________________________________________________
5. Talk with another student and write down another way you could model a chemical
change.
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
Why did you choose this model? ____________________________________________
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________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
6. Talk with another student and write down why a melting ice cube is not an example of
a chemical change. Try to refer to small, unseen particles in your answer.
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
7. Talk with another student and write down why baking a cookie is an example of a
chemical change. Try to refer to small, unseen particles in your answer
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
8. Think about what you have learned after matching the video with the according picture
below:
Draw arrows to show the first matches that you made.
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Why did you choose to make these first matches?_______________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
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Module 5: 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.
Thinking About Your Existing Ideas
In Module Four you learned about physical change. It is important to remember that in a
physical change the substance stays the same and just the state (solid, liquid, gas)
changes.
Talk with another student and write down three different examples of physical change.
Chemical Change
Scientists tell us that a physical change is different from a chemical change. A chemical
change is when a new substance is created. The new substance made by a chemical
change is different than the starting substances. For example, when a nail comes in
contact with air, a very slow chemical change happens. The rust you see is a new
substance, created by this contact.
Talk with another student and write down three examples of chemical change that are
happening in your classroom.
Baking and Chemical Change
Have you ever baked cookies? When you make cookies you start with ingredients like
flour, sugar, and eggs. You mix these together and then bake the dough in the oven.
Making and then baking cookies is an example of a chemical change. The cookies are
very different from the starting substances flour, sugar and eggs. When you eat the
cookie, further chemical reactions happen in your body.
Cooking an Egg
Have you ever cooked an egg? A cooked egg is very different from a raw egg. Raw egg
whites are liquid, while cooked egg whites are solid.
Talk with another student and write down why you think cooking an egg might be a
chemical change or a physical change.
Did you think that cooking an egg was a physical change or a chemical change?
Sometimes it is not easy to decide whether a change is physical or chemical.
Cooking an egg is a chemical change. As the egg heats up the raw egg whites get hard,
change color and a new substance is created.
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Using Small, Unseen Particles
Scientists tell us that ideas about small, unseen particles can help us to understand
whether a change is physical or chemical.
Important Ideas about Small, Unseen Particles
Chemical Change:
• Small, unseen particles break apart and then join together in different ways
• New substances are formed
Physical Change:
• Movement and arrangement of small, unseen particles changes (a change of state)
• Substance stays the same and no new substances are formed
A Good Enough Model of a Chemical Change
This is a good enough model of a chemical reaction. Watch what the sky divers do.
A Good Enough Model of a Chemical Change
This is a model of a chemical reaction. Watch the blue and green spheres carefully.
Watch the video again. Talk with another student and write down the ways the small,
unseen particles are changing.
What makes the videos good enough models for chemical change? Recall that in
chemical change, small unseen particles break apart and then join together to make
something new. How are the videos like the real thing? In the first video you saw sky
divers break apart and then join together in different ways making new shapes. In the
second video you saw green spheres and blue spheres break apart joined together to make
something new (a new substance!). How are the videos different from the real thing?
Particles in a chemical reaction are too small to see.
Talk with another student and write down another way you could model a chemical
change.
Conclusion
Chemical change happens all around you (cookies baking, nails rusting) and inside of you
(as you digest food). A chemical change is different from a physical change. Chemical
changes involve small, unseen particles that break apart and then join together in different
ways to form new substances. In the next module (Module Six) you will learn the clues
that help scientists decide whether a chemical change has occurred.
What have you learned?
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Talk with another student and write down why a melting ice cube is not an example of a
chemical change. Try to refer to small, unseen particles in your answer.
Talk with another student and write down why baking a cookie is an example of a
chemical change. Try to refer to small, unseen particles in your answer
Try to match the video with the according 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 upper picture is showing the physical change of ice melting into water.
The lower picture is showing the many chemical changes that happen when baking a
muffin.
Looking Ahead
We hope you enjoyed thinking about the small, unseen particles that take part in chemical
change.
In the next module (Module Six), you will get to look at the clues show a chemical
change has happened.
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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).