تلخيص شامل علوم منهج إنجليزي صف ثامن

الصف الصف الثامن
الفصل علوم الصف الثامن
المادة علوم الصف الثامن الفصل الاول
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تاريخ الإضافة 2020-06-29, 18:29 مساء

SCIENCE

Summary & Practice Sheets

Grade 8

Thermal Energy Elements and Chemical Bonds Chemical Reactions and Equations Electricity and Magnetism

HOT OR COLD

WORD BANK

Temperature: the average kinetic energy of the particles

Heat: the transfer of energy from hot to cold

Thermal Energy: the sum of kinetic and potential energy of the particles

Thermal energy can be transferred by

conduction

energy is transferred by direct contact

convection

energy is transferred by the motion of particles

radiation

energy is transferred by waves

thermal conductor

material that allows heat energy to be transferred

thermal insulator

material that does not allow heat energy to be transferred 

Revision Sheets

Chapter 1-Thermal Energy

Part A- True/False

Indicate whether the statement is true or false.

1. Potential energy is the energy of motion. 

2. Thermal energy is the temperature of the particles in a material. 

3. Temperature is a measure of the average kinetic energy of all the particles in an object. 

4. Heat is the movement of kinetic energy from a warmer object to a cooler object. 

5. The tool that is used for measuring temperature is called a ammeter.

6. The temperature at which all particle movement stops is 373 K. 

Part B- Multiple Choice 

Identify the choice that best completes the statement or answers the question. 

7. Which of the following objects has kinetic energy? 

a. a bicycle parked at the top of a hill 

b. leaves on the ground beneath a tree 

c. a football rolling across a field 

d. a sunny windowsill 

8. Which increases the kinetic energy of the particles in a bowl of soup? 

a. dividing the soup in half 

b. putting the soup in the refrigerator 

c. heating the soup for one minute on the stove 

d. decreasing the distance between the particles that make up the soup

9. What do convection and conduction have in common? 

a. they can both transfer thermal energy from one material to another. 

b. they can both occur in solids, liquids, and gases. 

c. they both produce currents 

d. they both involve the movement of particles 

10. Why is radiation the only way heat is transferred from the Sun to the Earth? 

a. because particles cannot move in the sun

b. because particles cannot move on earth

c. because it is the only kind of heat transfer that can occur in a vacuum

d. because it is the only kind of heat transfer that can occur over a large distance

11. Which is the transfer of thermal energy by the motion of heated particles in a gas or liquid from one part of a material to another? 

a. conduction 

b. radiation 

c. convection 

d. collision

12. Which is an increase in the size of a substance when the temperature is increased? 

a. diffusion 

b. thermal expansion 

c. thermal contraction 

d. specific heat 

13. Which energy conversion typically occurs in a heating appliance? 

a. chemical energy to thermal energy 

b. electric energy to thermal energy 

c. thermal energy to chemical energy 

d. thermal energy to mechanical energy 

14. Which of the following statements about thermal energy transfer is true? 

a. When heat is transferred by conduction, particles collide but remain in the same location.

b. Convection takes place most easily in solids.

c. The Sun is the only source of radiation. 

d. Convection does not occur naturally. 

Part C- Matching 

Match each term with its correct description 

a. thermal energy 

b. temperature 

c. heat 

d. radiation

e. conduction

f. convection

g. thermostat 

h. thermal contraction 

i. specific heat 

15. The average kinetic energy of the particles that make up a material.

16. The sum of the kinetic energy and the potential energy of the particles that make up a material. 

17. The movement of thermal energy from a warmer object to a cooler object. 

18. The amount of thermal energy required to increase the temperature of 1kg of a material by 1° C. 

19. A decrease in a material's volume when the temperature decreases. 

20. The transfer of thermal energy by the movement of particles from one part of a material to another.

21. The transfer of thermal energy between materials by the collisions of particles. 

22. The transfer of thermal energy from one material to another by electromagnetic waves. 

23. A device that regulates the temperature of a system. 

Part D- Short Answer 

Write the correct answer for each of the following questions. 

24. Explain how thermal energy and temperature differ. 

 

25. Identify one material that is a good thermal conductor and one material that is a good thermal insulator. 

 

26. What is a thermostat? List three appliances that are equipped with thermostats. 

 

27. How does a refrigerator keep food cold? 

 

28. What are the energy transformations in a car engine?

 

Part E- Organizing 

Complete the table by writing each phrase or statement under the correct heading, Each phrase or statement is used only once. Some examples have been done for you. 

• All matter radiates thermal energy. 

• involves the movement of thermal energy in a liquid 

• occurs in fluids 

• the transfer of thermal energy between materials because of collisions between the particles 

• the transfer of thermal energy from one material to another by electromagnetic waves 

• When particles with different kinetic energies collide, the particles with higher kinetic energy transfer energy to particles with lower kinetic energy 

Radiation 

Meaning:

A car receives thermal energy from the sun through this.

Conduction 

Meaning:

Continues until the thermal energy of all particles in contact is equal.

Convection 

Meaning: The transfer of thermal energy by the movement of particles from one part of a material to another. 

ATOMS: the unit of matter 

first shell holds a maximum of 2 electrons

third shell holds a maximum of 8 electrons 

second shell holds a maximum of 8 electrons

valence electron is an outermost electron 

COMPOUNDS 

covalent

two or more nonmetals share valence electrons

ionic

 metal transfers valence electrons to a nonmetal

metallic 

metals share pooled valence electrons

Representing Compounds 

 

PRACTICE-COMPOUNDS 

Label the following compounds with the correct model. 

 

CHARGING TIME! 

( - ) Electrons have a negative charge. 

( + ) Protons have a positive charge. 

 

PRACTICE-CALCULATING CHARGE

1. 4 - 10 = 

2. (-8) + 15 = 

3. 9 + (-10) = 

4. 13 + (-10) = 

5. 0 + (-15) = 

6. 10 + (-10) = 

7. Magnesium has 12 protons and 12 electrons. What will its charge be when it loses 2 electrons?

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