Grade 7 Science

Unit 2: Heat

Chapter 5: Scientists use the Particle Theory of Matter to describe temperature.

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Scientis

ts

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r Name:

Homeroom #: Matter

Matter is defined as: _____________________________________________________________

The Particle Theory of Matter (PTM)….

The 5 main points that make up this theory are:

1.

2.

3.

4.

5.

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Temperature

Temperature is defined as the ____________________________ of the particles of a substance.

Kinetic Energy

_________________________ is the energy of ___________________.

________________________ is then a measure of the ________________________________ of the particles of a substance.

Complete the following table.

Solid Liquid GasShape

Volume

Particle Arrangement

Particle Movement

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Expansion vs. Contraction

Expansion ___________________ the ___________________ of a substance.

Contraction __________________the ___________________ of a substance

Expansion occurs when:

the particles are __________________, they ____________ energy, move _________________,

___________________________ and take up ____________ space thereby

________________ their volume.

Contraction occurs when:

the particles are __________________, they ____________ energy, move _________________,

___________________________ and take up ____________ space thereby ________________ their volume.

Changes of State:

Use the diagram on page 60 to label the diagram:

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Graphing changes of state (a Heating Curve)

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Changes of state and the PTM

__________________ heat energy, ______________________ the kinetic energy and therefore

the ______________________________.

The particles ________________ their _____________________________ with their

neighbouring particles when kinetic energy is ___________________________.

Eventually, the __________________________________ will be great enough to break the

_____________________________ holding the particles together thereby changing state.

The opposite is true if heat energy is decreased.

Key Terms

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Matter (p. 136): ____________________________________________________________________________________________________________________________________________________________

Particle theory of matter (p. 138): __________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Kinetic energy (p. 138): ____________________________________________________________________________________________________________________________________________________________

Temperature (p. 141): ____________________________________________________________________________________________________________________________________________________________

Solid (p. 146): ____________________________________________________________________________________________________________________________________________________________

Liquid (p. 146): ____________________________________________________________________________________________________________________________________________________________

Gas (p. 146): ____________________________________________________________________________________________________________________________________________________________

Thermal Expansion (p. 149): ____________________________________________________________________________________________________________________________________________________________

Thermal Contraction (p. 149): ____________________________________________________________________________________________________________________________________________________________

Change of state (p. 160): ____________________________________________________________________________________________________________________________________________________________

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Melting (p. 160): ____________________________________________________________________________________________________________________________________________________________

Freezing (p. 160): ____________________________________________________________________________________________________________________________________________________________

Evaporation (p. 160): ____________________________________________________________________________________________________________________________________________________________

Condensation (p. 160): ____________________________________________________________________________________________________________________________________________________________

Sublimation (p. 160): ____________________________________________________________________________________________________________________________________________________________

Deposition (p. 160): ____________________________________________________________________________________________________________________________________________________________

Melting point (p. 161): ____________________________________________________________________________________________________________________________________________________________

Boiling point (p. 161): ____________________________________________________________________________________________________________________________________________________________

Heating curve (p. 164): ____________________________________________________________________________________________________________________________________________________________

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Chapter 5 Comprehension Questions

1. List the main points of the particle theory. (p. 138)

________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

1. When an object is moving, what type of energy does it have? (p. 138)

______________________________________________________________________________________________________________________________________________________

2. What are the two characteristics of an object that determines the amount of kinetic energy an object has? (p. 138)

____________________________ and ___________________________.

3. a) Two identical baseballs are hit with a baseball bat. One baseball is travelling at a speed of 35 m/s and the other is travelling at 23 m/s. Which baseball has more kinetic energy?

________________________________________________________________________b) Why?________________________________________________________________________________________________________________________________________________

4. a) A billiard ball and a Ping-Pong ball are travelling at the same speed. Which ball has more kinetic energy?

________________________________________________________________________b) Why?________________________________________________________________________________________________________________________________________________

5. Explain how particles in an object can be moving if the object is not moving. (p. 141)

______________________________________________________________________________________________________________________________________________________

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6. What is the connection between the kinetic energy of the particles in an object and the temperature of the object? (p. 141)

_________________________________________________________________________________________________________________________________________________________________________________________________________________________________

7. What term is used to describe the average kinetic energy of an object? (p. 141)

___________________________________________________________________________

8. a) List two characteristics of a solid: (p. 146)

______________________________________________________________________________________________________________________________________________________

b) List two characteristics of a liquid: (p. 146)

______________________________________________________________________________________________________________________________________________________

c) List two characteristics of a gas: (p. 146)

______________________________________________________________________________________________________________________________________________________

9. a) Describe the arrangement of particles in a solid. (p. 147)

______________________________________________________________________________________________________________________________________________________

b) Describe the arrangement of particles in a liquid. (p. 148)

______________________________________________________________________________________________________________________________________________________

c) Describe the arrangement of particles in a gas. (p. 148)

______________________________________________________________________________________________________________________________________________________

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10. How do the particles of a gas cause the volume of a container to increase when the temperature of the gas increases? (p. 149)

______________________________________________________________________________________________________________________________________________________

11. a) According to the particle theory of matter, why can particles of a liquid slide past one another but the particles of a solid cannot? (p. 149)

______________________________________________________________________________________________________________________________________________________

b) Why must particles of a solid remain beside each other? (150)

______________________________________________________________________________________________________________________________________________________

12. Give one reason why it is important for engineers who design buildings and bridges to understand thermal expansion and thermal contraction of materials. (p. 150)

______________________________________________________________________________________________________________________________________________________

13. What is another word for water vapour? (p. 160)

___________________________________________________________________________

14. What change of state is opposite to: (p. 160)

a) Evaporation: __________________________________________________________

b) Melting: _____________________________________________________________

c) Deposition: ___________________________________________________________

15. Use Table 5.1 on page 162 to answer the following questions:

a) What is the boiling point of mercury? ______________________________________

b) What is the state of nitrogen at -200°C? ____________________________________

c) What is the state of rubbing alcohol at 90°C? ________________________________

d) In what temperature range is tin a liquid? ___________________________________

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16. Use the particle theory to explain melting. (p. 164)

_________________________________________________________________________________________________________________________________________________________________________________________________________________________________

17. How does the particle theory explain why different substances have different melting and boiling points? (p. 164)

_________________________________________________________________________________________________________________________________________________________________________________________________________________________________

18. Explain how heat can be added to a substance but the temperature of the substance remains the same? (p. 164-165)

______________________________________________________________________________________________________________________________________________________

19. People often put salt on icy sidewalks or roadways. Give a possible explanation for why salt might cause ice to melt?

_________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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Create a list of 20 words or phrases from the descriptions below. Then find the words in the puzzle that follows. Words in phrases are not found together in the puzzle.

1. A moving object has this2. Explains what all matter is made of3. State of matter in which particles are not exerting forces on one another4. State of matter in which particles exert

attractive forces on one another but can still slide past one another

5. State of matter in which particles cannot move away from their neighbouring particles

6. Temperature at which a substance changes from a liquid to a solid

7. Changing from a gas to a liquid8. Changing from a gas to a solid9. Changing from a liquid to a gas10. Changing from a liquid to a solid11. Changing from a solid to a liquid12. Temperature at which a substance

changes from a solid to a liquid13. Changing from a solid to a gas14. Directly related to the average kinetic

energy of the particles of a substance15. When a substance is heated, it undergoes

thermal __ __ __ __ __ __ __ __ __16. When a substance is cooled, it undergoes

thermal __ __ __ __ __ __ __ __ __ __ __17. A graph of the temperature plotted

against time when a substance is being heated

18. Holds particles of a solid together19. Has mass and takes up space20. In addition to the speed of an object, it

affects the objects kinetic energy

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Practice TestCircle the letter of the best answer. 1. What determines the kinetic energy of an object?

A. mass and weight B. size and shape C. speed and massD. volume and speed

 2. To what is the temperature of an object is directly related?A. the average kinetic energy of its particles B. the average speed of its particles C. the kinetic energy of its particlesD. the total number of particles in the object

 3. Which statement is true?A.A gas forms a surface inside its container.B.A gas takes the shape of its container and completely fills the

container.C. A liquid has a fixed shape.D. A solid always forms a horizontal surface inside its container.

 4. Which statement about thermal expansion is true?A.Liquids and gases can undergo thermal expansion but solids cannot.B.Only gases undergo thermal expansion.C.Solids, liquids, and gases expand by the same amount when heated.D. Thermal expansion in gases is much greater than thermal expansion

of solids and liquids.

 5. In what the state is a substance when its temperature is between its melting point and its boiling point? A. gas B. liquidC. solidD. plasma

6.  According to the particle theory, particles that have enough energy to break all attractive forces with other particles of the same kind are in which state?A. gas B. liquidC. plasmaD.solid

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Match the term on the left with the best description on the right.Each description may be used only once.

Term Description

_____  7. matter

_____  8. thermal contraction

_____  9. temperature

_____ 10. kinetic energy

_____ 11. deposition

_____ 12. boiling point

A. the decrease in the volume of a substance when it cools

B. the change from a gas to a solidC. an object has this if it is movingD. the change from a gas to a liquidE. the temperature above which all of the

substance is in the gaseous stateF. anything that has mass and takes up spaceG. is directly related to the average kinetic

energy of its particlesH. the particles of an object are held together

by strong attractive forces

Short Answer Questions13. Name the two properties of an object that influence its kinetic energy.

________________________________________________________________________________________________________________________________________

14. List five important points that together describe the particle theory of matter.____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

15. Describe one similarity and one difference between a gas and a liquid.____________________________________________________________________________________________________________________________________________________________________________________________________________

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16. The following diagrams represent two different samples of the same gas. The lengths of the arrows represent the speed of the particles of the gases. (a) Which sample, A or B, has the higher temperature? Explain how you

decided on your answer. (b) Explain why the volumes of the samples are different.

____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

17. Explain why antifreeze is added to the water in the radiator of a car in the winter.____________________________________________________________________________________________________________________________________________________________________________________________________________

18. What is the difference between sublimation and evaporation?____________________________________________________________________________________________________________________________________________________________________________________________________________

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19. The diagrams below represent the particles in a substance as heat is being added to the substance. Describe any temperature changes that are occurring in each of the stages of heating that are shown in the diagram. Explain why the temperature is change or why it is not changing.

A B C D E

A _____________________________________________________________________________________________________________________________________

B _____________________________________________________________________________________________________________________________________

C _____________________________________________________________________________________________________________________________________

D _____________________________________________________________________________________________________________________________________

E _____________________________________________________________________________________________________________________________________

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