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CHAPTER

3 DIRECTED READING WORKSHEET

Understanding the Periodic Table

As you read Chapter 3, which begins on page 58 of your textbook, answer the following questions.

A Building as a Piece of Art! (p. 59)

1. Why would you cover a building with titanium?

Pre-Reading Questions (p. 58)

Answer these questions in your ScienceLog now. Then later, you'll have a chance to revise your answers based on what you've learned.

Start-Up Activity (p. 59)

2. What will you do in this activity?

Section 1: Electrons and the Periodic Table (p 60)

3. Elements have that make them unique.

Atomic Structure and Electrons (p. 60)

4. What are atoms made of?

5. What is an element's atomic number?

TEXAS EDITION, GRADE 8, UNIT 1 RESOURCES 13

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Chapter 3 Directed Reading, continued

6. For an atom to have no charge, there must be an equal number of

negatively charged and positively

charged 7. Energy levels farther from the nucleus hold electrons that have

energy than electrons in levels closer to the nucleus.

8. Valence electrons are the electrons in an atom's innermost energy level. True or False? (Circle one.)

Look at Figure 2 on page 61. Write the number of valence electrons in each of the following elements:

9. oxygen 10 sodium

11. In atoms of elements in Group 1 and 2, the number of

matches the

Section Review (p. 61)

Now that you've finished Section 1, review what you learned by answering the Section Review questions in your ScienceLog.

Periodic Table of the Elements (p. 62-63)

Use the periodic table on pages 62-63 of your text to fill in the answers to the following questions.

1. Which information is NOT included in each square of the periodic table in your text? a. atomic number c. melting point b. chemical symbol d. atomic mass

2. How can you tell that chlorine is a gas at room temperature?

3. Rows of elements are called , and

columns of elements are called or

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Chapter 3 Directed Reading, continued

4. Who will approve the official names for the elements greater than 109? a. the scientist who discovered each element b. a committee of scientists c. the chemists from a research institute

5. Silicon is a

Section 2: Grouping the Elements (p. 64)

1. Why do elements in a family or group generally have similar properties? a. They have the same atomic mass. b. They have the same number of protons in their nuclei. c. They often have the same number of valence electrons. d. They have the same number of total electrons.

Groups 1 and 2: Very Reactive Metals (p. 64)

2. The elements in Groups 1 and 2 are very reactive. Explain. •

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3. The elements in Groups 1 and 2 are so reactive that they are only

found in nature.

4. Which of the following is NOT true of alkali metals? a. They can be cut with a knife. b. They are usually stored in water. c. They are the most reactive of all the metals. d. They can easily lose their single outer electron.

5. How are the following alkali metal compounds useful?

a. sodium chloride

b. sodium hydroxide

c. potassium bromide

TEXAS EDITION, GRADE 8, UNIT 1 RESOURCES 15

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Chapter 3 Directed Reading, continued

6. Alkaline-earth metals have electrons

in their outer energy level. They are less and more than alkali metals.

7. Calcium is the alkaline-earth metal that is part of a compound

that keeps your bones and teeth healthy. True or False? (Circle one.)

Groups 3-12: Transition Metals (p. 66)

8. Elements in Group 3-12 are transition metals and some can

produce magnetic fields. True or False? (Circle one.)

9. Which of the following characteristics describe transition metals? (Circle all that apply.) a. good conductors b. more reactive than alkali and alkaline-earth metals c. one or two electrons in the outer energy level d. denser than elements in Groups 1 and 2

10. Mercury is different from the other transition metals in Figure 6. How?

11. Two rows of metals are placed at the bottom of the periodic table to save space. Elements in the

row are called lanthanides and are

shiny, metals.

12. Which lanthanide forms a compound that makes you see red on a computer screen like the one in Figure 7?

13. All atoms of actinides are radioactive. True or False? (Circle one.)

14. Which actinide is used in some smoke alarms?

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16 HOLT SCIENCE AND TECHNOLOGY

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Chapter 3 Directed Reading, continued

Mid-Section Review (p. 67)

Now that you've finished the first part of Section 2, review what you learned by answering the Mid-Section Review questions in your ScienceLog.

Groups 13-16: Groups with Metalloids (p. 68)

15. Look at Figure 8. Why was the most common element of Group 13, aluminum, once considered a precious metal?

16. What do diamonds and proteins have in common?

17. Phosphorous, which makes up about 80 percent of the air you

breathe, is used in fertilizers. True or False? (Circle one.)

18. Substances need the element to burn.

Complete the following section after you finish reading about Groups 13-16. Each of the following statements is false. Change the underlined word to make the statement true. Write the new word in the space provided.

19. Oxygen group elements have five electrons in the outer level.

20. The carbon group contains no nonmetals.

21. Nitrogen group and boron group elements vary in reactivity.

22. Not all carbon group and oxygen group elements are solid at room temperature.

Groups 17 and 18: Nonmetals Only (p. 70)

23. Which of the following statements is true? (Circle one.) a. Group 17 elements are the most reactive metals. b. Group 18 elements are the least reactive metals. c. Group 18 elements are the least reactive nonmetals.

TEXAS EDITION, GRADE 8, UNIT 1 RESOURCES 17

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Chapter 3 Directed Reading, continued

24. What does Figure 12 show about the physical properties of halogens?

25. Halogens are very reactive because of the number of electrons in

their outer energy level. True or False? (Circle one.) 26. What important use do the halogens iodine and chlorine have in

common?

27. Which of the following statements are true of noble gases? (Circle all that apply.) a. They are colorless and odorless at room temperature. b. They normally react with other elements. c. They are metals. d. They have a complete set of electrons in their outer energy level.

28. Take a moment to look at Figure 13. What happens when you pass an electric current through different noble gases?

Hydrogen Stands Apart (p. 71)

Mark each of the following statements True or False.

29. Hydrogen is useful as rocket fuel. 30. A hydrogen atom has two valence electrons.

31 Hydrogen is the most abundant element in the universe.

32. The physical properties of hydrogen are more like the properties of nonmetals than of metals.

33. Hydrogen does not react with oxygen.

Section Review (p. 71)

Now that you've finished Section 2, review what you learned by answering the Section Review questions in your ScienceLog.

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