1. Discussion: What’s New?
Physical or chemical change?
What is true about the kinds of matter present before and after a physical change?
How is matter different?
What is true about the types of matter present before and after the matter undergoes a chemical change
What substances were formed when the paper burned?
Would it be possible to change these types of matter back into a sheet of paper?

2. Matter is described by its properties and may undergo changes
Big Idea:
Matter is described by its properties and may undergo changes
Unit 1 Lesson 3 Physical and Chemical Changes
Essential Question: What are physical and chemical changes of matter?
Copyright © Houghton Mifflin Harcourt Publishing Company

3. P36-39 What are physical and Chemical Changes of Matter?
Physical Changes
Chemical Changes

4. Change of Appearance Physical Changes P36 - 38
Unit 1 Lesson 3 Physical and Chemical Changes
Change of Appearance
Physical Changes
A physical change is a change that affects one or more physical properties of a substance.
The appearance, shape, or size of a substance may be altered during a physical change.
Physical changes, such as changes in state, do not change the chemical identity of a substance.
5) Physical properties of the substance are changed.
7) Yarn was twisted, dyed, and knit to form sweater – it’s still wool.

5. Change of Appearance P38-39 Chemical Changes
Unit 1 Lesson 3 Physical and Chemical Changes
Change of Appearance
Chemical Changes
A chemical change is the process when one or more substances change into entirely new substances with different properties.
A substance’s identity changes because the chemical makeup changes.
Bonds get rearranged and/or new bonds form.
Influenced by temperature: At higher temperatures, chemical reactions happen more quickly

6. P38-39 8)
Flames
wood
Ashes
Smart Activity
9) Raising temp causes particles in matter to move more quickly. Increased motion causes particles to bump into each other which increases the rate of the chemical reaction
8) Burning wood is an example of a chemical change in which wood is transformed into new substances, such as ash and smoke

7. Change into entirely new substances with different properties
No change in Identity
Occur in matter
PROCESS
Bonds broken or new bonds form
Affects Physical Properties
Changes appearance
Physical Changes
Chemical Changes
LAW OF CONSERVATION
Chemical Makeup changes
Change in appearance, shape or size

8. Law of Conservation of Mass.
Law of Conservation of Mass
P42-43

9. Conservation Is the LawP
Unit 1 Lesson 3 Physical and Chemical Changes
Conservation Is the Law
What is the law of
conservation of mass?
French chemist Antoine Lavoisier studied chemical changes in which substances appeared to gain or lose mass.
The law of conservation of mass states that in ordinary chemical and physical changes, mass is not created or destroyed.
It is only transformed into different substances.

10. What is the law of conservation of mass?P
Unit 1 Lesson 3 Physical and Chemical Changes
What is the law of conservation of mass?
Most physical changes are reversible and follow the law of conservation of mass.
Mass is conserved during chemical changes.
The mass of the starting materials is the same as the mass of the end products.
Chemical Change

11. Law of Conservation of Mass.
Law of Conservation of Mass
Antoine Lavoisier
chemical and physical changes
mass is not created or destroyed.
Mass is conserved during chemical changes
Physical changes can be reversible
The mass of the starting materials is the same as the mass of the end products.

12. Look for the Signs How can you tell a chemical change has happened?
Unit 1 Lesson 3 Physical and Chemical Changes
Look for the Signs
How can you tell a chemical change has happened?
There are several signs that a chemical reaction has occurred.
Observing two or more of these signs during a change means you are likely observing a chemical change.

13. P40-41 How do you know a chemical change has happened?
if you observe two or more signs…
you likely are observing a chemical change
P40-41

14. Careful! How can you tell a chemical change has happened? p40 - 41
Unit 1 Lesson 3 Physical and Chemical Changes
How can you tell a chemical change has happened?
Odors can be produced during a chemical change.
Fizzing and foaming may mean gases are being produced.
The production of gas is often evidence of a chemical change.
Boiling also can produce gas bubbles, but boiling is a physical change.
Careful!

15. How can you tell a chemical change has happened?
Unit 1 Lesson 3 Physical and Chemical Changes
How can you tell a chemical change has happened?
A precipitate is a solid formed from liquids.
The formation of a precipitate can indicate a chemical change.
Energy that changes from one form to another can be evidence of a chemical change.
Changes in temperature and color can be signs of a chemical change.

16. Change
Signs/Observations
Type of Change
Boiling Water
Bubbles formed
No new substance formed
physical
Baking a Cake
Odor, change in energy, color change
chemical
Burning Wood
Change in energy, color change, wood  ash
Painting a door
Color change
No new substance is formed

17. How do you know a chemical change has happened?
if you observe two or more signs…
you likely are observing a chemical change
Production of
a Gas
Production of
an Odor
Change in
Color
Change in
Energy
Precipitate Forms
Energy changes form/
Temperature change
Rotting egg = sulfur smell
Fizzing or Foaming
2 liquids combine to form a solid
Gray iron forms brown rust
Antacid tablet in water produces carbon dioxide
Sour milk – bacteria formed a new substance
Chemical energy converts to light and heat

18. Physical or Chemical Change?
Part B
Read each scenario. Decide whether a physical or chemical change has occurred and give evidence for your decision. The first one has been done for you to use as an example.
Scenario
Physical or Chemical Change?
Evidence… 1.
Yumm! A student removes a loaf of bread hot from the oven. The student cuts a slice off the loaf and spreads butter on it.
Physical
No change in substances.
No unexpected color change, temperature change or gas given off. 2.
Your friend decides to toast a piece of bread, but leaves it in the toaster too long. The bread is black and the kitchen if full of smoke. 3.
You forgot to dry the bread knife when you washed it and reddish brown spots appeared on it.
The bread is burned- Color change to black and smoke released- odor change
Chemical
The knife changed colors- rust
Chemical

19. Physical or Chemical Change?
Scenario
Physical or Chemical Change?
Evidence… 4.
You blow dry your wet hair. 5.
In baking biscuits and other quick breads, the baking powder reacts to release carbon dioxide bubbles. The carbon dioxide bubbles cause the dough to rise. 6.
You take out your best silver spoons and notice that they are very dull and have some black spots.
Did not change your hair- evaporated the water
Physical
Releasing of gases and changing to another substance batter to bread
Chemical
The silver is tarnished- similar to rusting (reacted with oxygen) changed colors
Chemical

20. Physical or Chemical Change?
Scenario
Physical or Chemical Change?
Evidence… 7.
A straight piece of wire is coiled to form a spring. 8.
Food color is dropped into water to give it color. 9.
Chewing food to break it down into smaller particles represents a _________ change, but the changing of starch into sugars by enzymes in the digestive system represents a ___________change.
10.
In a fireworks show, the fireworks explode giving off heat and light.
Its still the same piece of wire- changed appearance
Physical
Its still water- just tinted a different color
Physical
Breaking up food to smaller pieces
Physical
Changing the food to something else
Chemical
Heat and light are released –changing energy
Chemical