Lesson 2 | Matter and Its Changes



Name Date Class

LESSON 2

Matter and Its Changes

A. Changes of Matter

1. Matter changes with the season, including changes in the

of leaves and in the of

the air.

2. Matter can change in many ways, including changes

and changes.

B. What are physical changes?

1. In a physical change, the of the substance does not

change.

2. one substance in another does not change the

identities of the substances.

3. The formation of ice on the surface of a lake is an example of

a(n) .

4. Changes in state involve changes in the amount of that

the particles in a substance have.

5. The at which one state of matter changes into another

depends on how much energy is added or taken away from the substance.

C. What are chemical changes?

1. In a chemical change, the substances that make up matter change into other

substances with physical properties and chemical

properties.

2. Changes in , density, and state of matter can be signs of

a chemical change.

3. The formation of a(n) substance is the only sure sign of

a chemical change.

a. Formation of a(n) might be signaled by bubbles or an

odor.

b. Formation of a(n) , a solid that sometimes forms

when two liquids combine, is a sign of a chemical change.

c. A change in might or might not be a sign of a

chemical change. It depends on whether a(n) forms.

Matter: Properties and Changes 29

Name Date Class

Lesson Outline continued

4. Energy is a sign that chemical change is involved.

5. Energy in the form of is needed for chemical reactions

such as photosynthesis.

6. is a chemical reaction that only occurs if plants are

exposed to light.

7. Many changes cannot be .

8. is always conserved during physical and chemical

changes.

9. The law of conservation of mass states that the total mass before a(n)

is the same as the total mass after it.

10. The mass of an unburned match plus the mass of the oxygen it reacts with

the mass of the ashes and of all the gases given off

when the match burns.

D. Comparing Physical and Chemical Changes

1. Changing the shape of a piece of clay is a(n) change.

2. Spoiling foods are examples of change.

30 Matter: Properties and Changes

Name Date Class

LESSON 2

Matter and Its Changes

Directions: Complete this chart by choosing terms from the word bank and writing them in the correct spaces.

boiling burning chemical changes dissolving

melting photosynthesis rusting

Directions: Circle the term in parentheses that correctly completes each sentence.

8. When matter undergoes a physical or chemical change, the amount of mass

(changes/stays the same).

9. All chemical reactions result in the production of a new substance and involve a

change in (energy/volume).

10. Some changes cannot be (repeated/reversed).

11. Photosynthesis is an example of a (physical/chemical) change that almost all living

things rely on.

32 Matter: Properties and Changes

Name Date Class

LESSON 2

Matter and Its Changes

Directions: Complete each item on the lines provided.

1. What is a physical change in matter?

2. All changes in the of matter are physical changes.

3. What is a chemical change in matter?

4. Name three signs of a chemical change that are mentioned in the lesson.

5. What is the only sure sign of a chemical change?

6. What kind of energy do plants need to perform photosynthesis?

7. What happens to the total amount of mass during a physical or chemical change?

Directions: Tell whether the following changes are physical (P) or chemical (C) and whether they are

reversible (R) or nonreversible (N).

8. iron rusting

9. salt dissolving

10. water freezing

11. wood burning

12. pottery shattering

Matter: Properties and Changes 33

Name Date Class

LESSON 2

Word Building Activity: Sentence Completion

Directions: Study the terms and definitions below. Then write the term that correctly completes each sentence.

Each term is used only once.

boiling point n. temperature at which a liquid changes to a gas

chemical property n. the ability or inability of a substance to combine with or change

into one or more new substances

density n. the mass per unit volume of a substance

melting point n. temperature at which a solid changes to a liquid

physical change n. any change in matter in which the identity of the matter is

not changed

physical property n. any characteristic of a substance that can be observed without

changing the substance

solubility n. the ability of one material to dissolve in another

1. The of a material is the same, despite the size or amount

of the material.

2. When an ice cube melts and becomes a liquid, it undergoes a

because the process does not change the composition of

the matter.

3. Water turns into a gas when it is heated to 100°C because that temperature is

its .

4. It takes a lot of energy to change solid steel into a liquid, because the

of steel is 1,370°C.

5. One well-known of diamonds is hardness.

6. Sugar dissolves quickly in tea because it has a high in

water.

7. Objects made of iron can rust, which is a of the metal.

34 Matter: Properties and Changes

Name Date Class

LESSON 2

Matter and Its Changes

Key Concept How are physical changes different from chemical changes?

Directions: On the line before each change, write P for physical or C for chemical.

1. glass melting

2. wood burning

3. bread baking

4. water vapor condensing

5. iron rusting

6. leaves changing color

7. sugar dissolving

8. oxygen becoming liquid

9. silver tarnishing

Directions: Some changes can be reversed—others cannot. Put a check mark on the line before each change that

is reversible. Put an X on the line before each change that is not reversible.

10. making water into ice

11. hard-boiling an egg

12. dissolving salt in water

13. breaking a window

14. scorching a fabric

Matter: Properties and Changes 37

Name Date Class

LESSON 2

Matter and Its Changes

Key Concept How are physical changes different from chemical changes?

Directions: Complete these diagrams by choosing terms from the word bank and writing them in the correct

spaces.

burns evaporates heat ice light

spark sunlight vapor water wood

Directions: Complete each item below.

11. Put a star next to the words above that are sources of energy or the release of energy.

12. Ice must absorb heat to melt into water. What must water do to evaporate?

38 Matter: Properties and Changes

Name Date Class

LESSON 2

Matter and Its Changes

Key Concept How are physical changes different from chemical changes?

Directions: Work with a partner. Tell which signs of a chemical change occur with each of the processes below.

1. a log burning

2. photosynthesis

3. oxidation of silver

Directions: Complete each item below with your partner.

4. Another name for a chemical change is a(n) .

5. Respiration is a chemical change that occurs inside your body. What gas do you release

every time you exhale?

Matter: Properties and Changes 39

Name Date Class

LESSON 2

Matter and Its Changes

Key Concept How do physical and chemical changes affect mass?

Directions: Complete each item below on the lines provided.

1. The principle that mass is never lost in physical and chemical changes is known as the

law of .

2. The ashes left by a forest fire don’t weigh as much as the trees did. Knowing that mass

is never destroyed, explain what happened to some of the mass of the trees as they

burned.

3. When water freezes, it expands in volume by 10 percent. If you froze 200 g of water,

what would be the mass of the resulting block of ice? Explain your answer.

4. What happens to the mass of a soft drink when you open it?

5. If you could put a sealed room on a very sensitive scale and open a thousand soft drink

cans inside it, would the mass reading on the scale go up, go down, or stay the same?

Explain your answer.

40 Matter: Properties and Changes

Lesson 2: Matter and Its Changes

A. Changes of Matter

1. Matter changes with the season, including changes in the color of leaves and in the temperature of the air.

2. Matter can change in many ways, including physical changes and chemical changes.

B. What are physical changes?

1. In a physical change, the identity of the substance does not change.

2. Dissolving one substance in another does not change the identities of the substances.

3. The formation of ice on the surface of a lake is an example of a(n) change in state.

4. Changes in state involve changes in the amount of energy that the particles in a substance have.

5. The rate at which one state of matter changes into another depends on how much energy is added or taken away from the substance.

C. What are chemical changes?

1. In a chemical change, the substances that make up matter change into other substances with different physical properties and chemical properties.

2. Changes in color, density, and state of matter can be signs of a chemical change.

3. The formation of a(n) new substance is the only sure sign of a chemical change.

a. Formation of a(n) gas might be signaled by bubbles or an odor.

b. Formation of a(n) precipitate, a solid that sometimes forms when two liquids combine, is a sign of a chemical change.

c. A change in color might or might not be a sign of a chemical change. It depends on whether a(n) new substance forms.

4. The release of thermal energy is a sign that chemical change has occurred.

5. Energy in the form of light is needed for chemical reactions such as photosynthesis.

6. Photosynthesis is a chemical reaction that only occurs if plants are exposed to light.

7. Many changes cannot be reversed.

8. Mass is always conserved during physical and chemical changes.

9. The law of conservation of mass states that the total mass before a(n) chemical reaction is the same as the total mass after it.

10. The mass of an unburned match plus the mass of the oxygen it reacts with equals the mass of the ashes and of all the gases given off when the match burns.

D. Comparing Physical and Chemical Changes

1. Changing the shape of a piece of clay is a(n) physical change.

2. Spoiling foods are examples of chemical change.

Content Practice A (page 32)

1–3. (in any order) dissolving, melting, boiling

4. Chemical changes

5–7. (in any order) burning, rusting, photosynthesis

8. stays the same

9. energy

10. reversed

11. chemical

Content Practice B (page 33)

1. a change in which the identity of the material stays the same

2. state

3. a change in matter in which the substances that make up the matter change into other substances that have different chemical and physical properties

4. formation of a gas, formation of a precipitate, change in color

5. a change in energy

6. light energy, usually in the form of sunlight

7. It stays the same (or it is conserved).

8. C, N

9. P, R

10. P, R

11. C, N

12. P, N

Language Arts Support (page 34)

1. density

2. physical change

3. boiling point

4. melting point

5. physical property

6. solubility

7. chemical property

Key Concept Builder (page 37)

1. P

2. C

3. C

4. P

5. C

6. C

7. P

8. P

9. C

10. check mark

11. X

12. check mark

13. X

14. X

Key Concept Builder (page 38)

1. spark

2. wood

3. burns

4. heat

5. light

6. sunlight

7. ice

8. water

9. evaporates

10. vapor

11. stars next to spark, sunlight, heat, light

12. absorb even more heat

Key Concept Builder (page 39)

1. the creation of ashes and release of carbon dioxide and water vapor

2. the release of oxygen and production of sugars

3. the silver tarnishes to a dull, gray color

4. chemical reaction

5. carbon dioxide

Key Concept Builder (page 40)

1. conservation of mass

2. Some of the mass of the trees is converted to carbon dioxide and other gases.

3. 200 g; the mass of the water does not change. The water expands and becomes less dense.

4. It decreases slightly, because it gives up carbon dioxide.

5. The mass of the room would stay the same because all the gas released by the beverages would be contained within the room.

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Lesson Outline

Content Practice A

Changes to Matter

4.

Physical changes

examples

examples

5.

1.

6.

2.

7.

3.

Content Practice B

Language Arts Support

Key Concept Builder

Key Concept Builder

Physical

Chemical

6.

1.

melts

ignites

7.

2.

into

which

8.

3.

which later

producing

9.

4.

to become a

and

5.

10.

Key Concept Builder

Many signs indicate that substances have undergone a chemical change rather than

a physical change. These signs show that a new substance has been formed from a

chemical reaction.

Three signs of a chemical change are

• changes in color,

• the release of a gas, and

• the formation of a new solid substance, such as a precipitate.

Key Concept Builder

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