Chapter 6: The Periodic Table and Periodic Law - irion · PDF fileCHAPTER The Periodic Table and Periodic Law Section 6.1 ... Guided Reading Audio Program,Chapter 6 Cooperative Learning

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Section 6.2Classification of theElements2 sessions

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1. Trace the development and identifykey features of the periodic table.

2. Explain why elements in the samegroup have similar properties.

3. Identify the four blocks of the periodictable based on electron configuration.

4. Compare period and group trends ofseveral properties.

5. Relate period and group trends inatomic radii to electron configuration.

Discovery Lab: Versatile Metals, p. 151Astronomy Connection, p. 152Problem-Solving Lab: Francium—solid,liquid, or gas? p. 155

Careers Using Chemistry: Medical LabTechnician, p. 160ChemLab: Descriptive Chemistry of theElements, pp. 170–171

MiniLab: Periodicity of Molar Heats ofFusion and Vaporization, p. 164ChemLab: Descriptive Chemistry of theElements, pp. 170–171How It Works: Television Screen, p. 172

Section Objectives Activities/Features

CHAPTER The Periodic Table and Periodic Law

Section 6.1Development of theModern Periodic Table1 session

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National Science State/Local Reproducible Masters TransparenciesContent Standards Standards

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CHAPTER 6 RESOURCE MANAGER

UCP.1, UCP.2, UCP.5;A.1, A.2; B.1, B.2; E.2;G.1, G.2, G.3

1(A), 2(D), 2(E), 3(A),3(E), 4(C), 4(D), 6(C)

UCP.1, UCP.2, UCP.5;A.1; B.1, B.2

3(D), 4(D), 6(A)

UCP.1, UCP.2, UCP.5;A.1, A.2; B.1, B.2, B.6;E.1, E.2; G.2, G.3

1(A), 2(A), 2(B), 2(C),2(D), 2(E), 3(A), 3(C),3(E), 4(A), 4(C), 4(D),6(A), 6(C)

Study Guide for Content Mastery,pp. 35–36 ChemLab and MiniLabWorksheets, pp. 21–24 Laboratory Manual, pp. 41–48L2

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Section Focus Transparency 22

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Study Guide for Content Mastery,pp. 31–32 L2

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Teaching Transparency 18

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Study Guide for Content Mastery,pp. 33–34 ChemLab and MiniLabWorksheets, pp. 22–24 Challenge Problems, p. 6 L3

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Teaching Transparency 19

Math Skills Transparency 6

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Key to National Science Content Standards: UCP � Unifying Concepts andProcesses, A � Science as Inquiry, B � Physical Science, C � Life Science,D � Earth and Space Sciences, E � Science and Technology,F � Science in Personal and Social Perspectives, G � History and Nature of Science

Refer to pages 4T–5T of the Teacher Guide for an explanation of the National Science Content Standards correlations.

150C

ChemLab (pages 170–171)stoppered test tubes containing small samples of elements, plastic dishes containing samples ofelements, conductivity tester, 1.0M HCl, test tubes (6), test-tube rack, 10-mL graduated cylinder,spatula, small hammer, glass marking pencil

Discovery Lab (page 151)samples of copper (coins, wire, shot, strips, etc.), masking tape, low-voltage light bulb withsocket, connecting wires, battery

MiniLab (page 164)graphing calculator or computer graphing program or graph paper and pencil, data table of molarheats of fusion and vaporization

Demonstration (pages 166–167)overhead projector, explosion shield, 600-mL beakers (3), phenolphthalein indicator, clear plasticwrap, wire screen (10 cm � 10 cm), small cubes (approximately 2 mm) of lithium, sodium, andpotassium, water

For a review of solution preparation, see page 46T of the Teacher Guide.

Quantities are for a class of 30 students.

ChemLab (pages 170–171)1.0M hydrochloric acid Add 25 mL concentrated (12M) hydrochloric acid to 275 mL distilled

water while stirring. CAUTION: Do NOT add the water to the acid.Demonstration (pages 166–167)

phenolphthalein indicator solution Dissolve 0.1 g phenolphthalein powder in 70 mL 95% ethanol. Make up to 100 mL final volume with distilled water.

Materials List

Preparation of Solutions

CHAPTER The Periodic Table and Periodic Law6

Resource Manager

Chapter Assessment, pp. 31–36MindJogger VideoquizzesAlternate Assessment in the Science ClassroomTestCheck Software Solutions Manual, Chapter 6Supplemental Problems, Chapter 6Performance Assessment in the Science ClassroomChemistry Interactive CD-ROM, Chapter 6 quiz

Spanish Resources Guided Reading Audio Program, Chapter 6Cooperative Learning in the Science ClassroomLab and Safety Skills in the Science ClassroomLesson PlansBlock Scheduling Lesson Plans

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Assessment Resources Additional Resources

Texas Lesson PlansTexas Block Scheduling Lesson Plans

150D

Level 1 activities should be appropriate for students withlearning difficulties.

Level 2 activities should be within the ability range of all students.

Level 3 activities are designed for above-average students.

ELL activities should be within the ability range ofEnglish Language Learners.

Cooperative Learning activities are designedfor small group work.

These strategies represent student products that can beplaced into a best-work portfolio.

These strategies are useful in a block scheduling format.

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VIDEOTAPE/DVDMindJogger Videoquizzes,Chapter 6

VIDEODISCCosmic ChemistryPeriodic Table; metals and nonmetals,Still

CD-ROMChemistry: Matter and ChangeThe Periodic Table, ExplorationTransuranium Elements, VideoActivity of Alkali Metals, Demonstration

The following multimedia for this chapter are available from Glencoe.

Look for the following icons for strategies that emphasize different learning modalities.KinestheticMeeting Individual Needs, pp. 156, 160; Quick

Demo, p. 161

Visual-SpatialVisual Learning, pp. 153, 154; Portfolio, p. 159;

Check for Understanding, p. 161; Reteach, pp. 162,169; Meeting Individual Needs, p. 165; Math inChemistry, p. 165

InterpersonalChemistry Journal, p. 157; Reteach, p. 158

IntrapersonalMeeting Individual Needs, p. 153; Chemistry

Journal, p. 168

LinguisticCheck for Understanding, p. 158; Chemistry

Journal, p. 161

Logical-MathematicalMath in Chemistry, p. 167

Key to Teaching Strategies

Glencoe Technology

Multiple Learning Styles

CHAPTER 6 RESOURCE MANAGER

Assessment Planner

Portfolio AssessmentPortfolio, TWE, pp. 159, 173Assessment, TWE, p. 161

Performance AssessmentAssessment, TWE, p. 166ChemLab, SE, pp. 170–171Discovery Lab, SE, p. 151MiniLab, SE, p. 164Problem-Solving Lab,TWE, p. 155

MiniLab, TWE, p. 164

Knowledge AssessmentAssessment, TWE, p. 156Section Assessment, SE,pp. 158, 162, 169

Chapter Assessment, SE,pp. 174–177

Demonstration, TWE, p. 167

Skill AssessmentAssessment, TWE, pp. 158,162, 169

ChemLab, TWE, p. 171

The Periodic Table andPeriodic Law

150 Chapter 6

What You’ll LearnYou will explain why ele-ments in a group havesimilar properties.

You will relate the groupand period trends seen inthe periodic table to theelectron configuration ofatoms.

You will identify the s-, p-,d-, and f-blocks of the periodic table.

Why It’s ImportantThe periodic table is the sin-gle most powerful chemistryreference tool available toyou. Understanding its organ-ization and interpreting itsdata will greatly aid you inyour study of chemistry.

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CHAPTER 6

Visit the Chemistry Web site atscience.glencoe.com to findlinks about the periodic table.

The phases of the moon and thecycle of ocean tides are both peri-odic events, that is, they repeat ina regular manner.

6CHAPTER

150

Tying to PreviousKnowledgeHave students review the followingconcepts before studying thischapter.Chapter 4: atomic structureChapter 5: electron configurations,valence electrons, electron-dotstructures

Using the PhotoAsk students to estimate the periodof each of the two periodic eventsshown in the photo—the tides andthe phases of the Moon. The Mooncycles through its phases inapproximately 29.5 days. Twohigh tides and two low tidesoccur every 24 hours in most locations.

Chapter ThemesThe following themes from theNational Science EducationStandards are covered in thischapter. Refer to page 4T of theTeacher Guide for an explanationof the correlations.Systems, order, and organization(UCP.1)Evidence, models, and explanation(UCP.2)Form and function (UCP.5)

Resource ManagerResource Manager

Study Guide for Content Mastery, pp. 31–32

Section Focus Transparency 20 and Master

Solving Problems: A Chemistry Handbook, Section 6.1 L2

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DISCOVERY LAB

Purpose Students will observe several characteris-tics of metals that make them versatile.

Safety and DisposalWarn students to exercise caution whenbending the copper samples, as they mayhave sharp edges that could cause cuts.

Teaching Strategies• Form sets of the following types of

copper samples: wires of differentgauges, round shot, flat strips, granules,and shiny and dull pennies. If all of theseare not available, use whatever kinds ofcopper samples you can find.

• Have as many samples of copper avail-able as possible. Remind students tobend samples gently so that they do notbreak. Review the terms ductile (drawninto wire) and malleable (bendable).

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6.1Section

1 Focus

Before presenting the lesson, displaySection Focus Transparency 20on the overhead projector. Havestudents answer the accompanyingquestions using Section FocusTransparency Master 20.

2 TeachConcept DevelopmentHelp students understand why theperiodic table has become such avaluable tool for chemists. Reinforcethe point that in Lavoisier’s time,the late 1790s, there were only 23 known elements, while today,there are more than 110. The peri-odic table organizes all the knownelements, allowing general proper-ties to be easily determined just byidentifying an element’s position onthe table.

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Pages 150–1511(A), 2(E), 3(E), 4(C), 6(C)

Focus Transparency

6.1 Development of the Modern Periodic Table 151

DISCOVERY LAB

Materials

tapesamples of copperlight socket with bulb, wires,and battery

Objectives • Trace the development and

identify key features of theperiodic table.

Vocabularyperiodic lawgroupperiodrepresentative elementtransition elementmetalalkali metalalkaline earth metaltransition metalinner transition metalnonmetalhalogennoble gasmetalloid

Section 6.1

Development of the ModernPeriodic Table

You have already learned much in your study of chemistry. Wouldn’t it benice if you could easily organize the chemistry knowledge you are acquir-ing? You can, with the help of the periodic table. It is called a periodic tablebecause, much like the phases of the moon, one of which is shown in the chapter opening photo, the properties of the elements in the table repeat in aperiodic way. The periodic table will be an invaluable tool as you continuethis course in chemistry. However, before you learn about the modern peri-odic table, a recounting of the history behind the table’s development will helpyou understand its significance.

History of the Periodic Table’s DevelopmentIn the late 1790s, French scientist Antoine Lavoisier compiled a list of elementsknown at the time. The list contained 23 elements. Many of these elements,such as silver, gold, carbon, and oxygen, were known since prehistoric times.The 1800s brought many changes to the world, including an explosion in thenumber of known elements. The advent of electricity, which was used to breakcompounds down into their component elements, and the development of thespectrometer, which was used to identify the newly isolated elements, playedmajor roles in the advancement of chemistry. So did the industrial revolution

Be careful when bending the copper samples, as they mayhave sharp edges.

Versatile Metals

Avariety of processes can be used to shape metals into different forms. Because of their physical properties, metals are used in a

wide range of applications.

Safety Precautions

Procedure

1. Observe the different types of copper metal that your teachergives you. Write down as many observations as you can about eachof the copper samples.

2. Try gently bending each copper sample (do not break the samples).Record your observations.

3. Connect each copper sample to the circuit as shown in the photo.Record your observations.

Analysis

What properties of copper are similar in all of the samples? How dothe samples of copper differ? List several common applications ofcopper. What properties make metals such as copper so versatile?

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Section Focus Transparency 20 ClassificationUse with Chapter 6, Section 6.1

Chemistry: Matter and Change

Section Focus Transparencies

How are most library books classified?Why is such a classification system useful?

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Expected ResultsObservations should include color (orange-red); descriptions of shapes; that all shapesare bendable except penny and shot; andthat all samples conduct electricity.

AnalysisAll samples are hard, shiny, conduct elec-tricity, and similar in color (though somemay be duller than others). Except for the

shot and the penny, all the samples can bebent fairly easily. The samples differprimarily in shape and surface texture.Copper wires are often used to transmitelectricity and copper coatings are oftenused in cookware. Metals are very versa-tile because of their malleability, ductility,strength, and good thermal and electricalconductivity.

of the mid-1800s, which led to the development of many new chemistry-basedindustries, such as the manufacture of petrochemicals, soaps, dyes, and fertil-izers. By 1870, there were approximately 70 known elements—almost triplethe number known in Lavoisier’s time. As you can see in Figure 6-1, the indus-trial revolution also created problems, such as increased chemical pollution.

Along with the discovery of new elements came volumes of new scien-tific data related to the elements and their compounds. Chemists of the timewere overwhelmed with learning the properties of so many new elements andcompounds. What chemists needed was a tool for organizing the many factsassociated with the elements. A significant step toward this goal came in 1860,when chemists agreed upon a method for accurately determining the atomicmasses of the elements. Until this time, different chemists used differentmass values in their work, making the results of one chemist’s work hard toreproduce by another. With newly agreed upon atomic masses for the ele-ments, the search for relationships between atomic mass and elemental prop-erties began in earnest.

John Newlands In 1864, English chemist John Newlands (1837–1898),who is shown in Figure 6-2, proposed an organization scheme for the ele-ments. Newlands noticed that when the elements were arranged by increas-ing atomic mass, their properties repeated every eighth element. In otherwords, the first and eighth elements had similar properties, the second andninth elements had similar properties, and so on. A pattern such as this iscalled periodic because it repeats in a specific manner. Newlands named theperiodic relationship that he observed in chemical properties the law ofoctaves, because an octave is a group of musical notes that repeats everyeighth tone. Figure 6-2 also shows how Newlands organized the first 14“known” elements (as of the mid-1860s). If you compare Newlands’sarrangement of the elements with the modern periodic table on the insideback cover of your textbook, you’ll see that some of his rows correspond tocolumns on the modern periodic table. Acceptance of the law of octaves washampered because the law did not work for all of the known elements. Also,unfortunately for Newlands, the use of the word octave was harshly criti-cized by fellow scientists who thought that the musical analogy was unsci-entific. While Newlands’s law was not generally accepted, the passage of afew years would show that he was basically correct; the properties of ele-ments do repeat in a periodic way.

Meyer, Mendeleev, and Moseley In 1869, German chemist Lothar Meyer(1830–1895) and Russian chemist Dmitri Mendeleev (1834 –1907) eachdemonstrated a connection between atomic mass and elemental properties.Mendeleev, however, is generally given more credit than Meyer because hepublished his organization scheme first and went on to better demonstrate itsusefulness. Like Newlands several years earlier, Mendeleev noticed that whenthe elements were ordered by increasing atomic mass, there was a repetition,or periodic pattern, in their properties. By arranging the elements in order ofincreasing atomic mass into columns with similar properties, Mendeleevorganized the elements into the first periodic table. Mendeleev and part of hisperiodic table are shown in Figure 6-3. Part of the reason Mendeleev’s tablewas widely accepted was that he predicted the existence and properties ofundiscovered elements. Mendeleev left blank spaces in the table where hethought the undiscovered elements should go. By noting trends in the prop-erties of known elements, he was able to predict the properties of the yet-to-be discovered elements scandium, gallium, and germanium.

152 Chapter 6 The Periodic Table and Periodic Law

Figure 6-1

A resident of London, Englandinvented the word smog todescribe the city’s filthy air, acombination of smoke and natu-ral fog. The quality of London’sair became so poor that in 1952about 4000 Londoners died dur-ing a four-day period. This inci-dent led to the passage ofEngland’s Clean Air Act in 1956.

AstronomyCONNECTION

The element technetium doesnot occur naturally on Earth. It

has been found in stars. Astro-nomers analyze the chemicalcomposition of stellar matter byusing an instrument called a spec-troscope, which separates thelight from a star into individualcolors, much as a prism does.Although each star has a uniquecomposition of elements, all starsare composed mainly of the gaseshydrogen and helium. The Sun,for example, is estimated to beabout 70 percent hydrogen and28 percent helium. A tiny fractionof a star’s mass may come fromheavier elements such as oxygen,carbon, nitrogen, calcium, orsodium. Two percent of our Sun’smass comes from these heavierelements.

Go to the Chemistry InteractiveCD-ROM to find additionalresources for this chapter.

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IdentifyingMisconceptions

Students often have difficultyunderstanding the vast amountof information that can beinferred by an element’s posi-tion on the periodic table.Uncover the MisconceptionFirst, have students create a listof phenomena or events that areperiodic or cyclical. This listmight include seasons of theyear, phases of the moon, theschool year, days of the week,octaves in music, and mathfunctions, such as sine or cosine.Then, ask them to explain whythe word periodic is appropriateto the periodic table. Demonstrate the ConceptPlay a game of Ten Questions orWho am I? Tell students thatyou are an element and thatthey’ll be provided with clues(properties) about your (theelement’s) identity. Start withseveral elements with familiarproperties. Increase the diffi-culty of the game by selectingelements with less familiarproperties. Suggest that there aretoo many elements and proper-ties for scientists to remember.The periodic table helps scien-tists organize seemingly unre-lated properties and chemicalfacts so that general trends canbe recognized.Assess New KnowledgePick five elements that representperiodicity. Using a separate filecard for each element, list severalproperties of the element. Leaveone of the properties for one ofthe elements as an unknown.Have students organize the fivecards and predict the missinginformation. Have them explainhow they were able to predict themissing information.

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Internet Address Book

Note Internet addresses that you find useful in thespace below for quick reference.

Mendeleev’s table, however, was not completely correct. After severalnew elements were discovered and atomic masses of the known elements weremore accurately determined, it became apparent that several elements in histable were not in the correct order. Arranging the elements by mass resultedin several elements being placed in groups of elements with differing prop-erties. The reason for this problem was determined in 1913 by English chemistHenry Moseley. As you may recall from Chapter 4, Moseley discovered thatatoms of each element contain a unique number of protons in their nuclei—the number of protons being equal to the atom’s atomic number. By arrang-ing the elements in order of increasing atomic number instead of increasingatomic mass, as Mendeleev had done, the problems with the order of the ele-ments in the periodic table were solved. Moseley’s arrangement of elementsby atomic number resulted in a clear periodic pattern of properties. The state-ment that there is a periodic repetition of chemical and physical properties ofthe elements when they are arranged by increasing atomic number is calledthe periodic law.


Figure 6-2

John Newlands noticed that theproperties of elements repeatedin a manner similar to an octaveon a musical scale (A, B, C, D, E,F, G, A, and so on). While thereare some similarities betweenthe law of octaves and the mod-ern periodic table, there also aresignificant differences. You‘llnotice that some of the chemicalsymbols do not match. For exam-ple, beryllium (Be) was alsoknown as glucinum (G). Whatsimilarities and differences canyou identify?

HA 1 FA 8

LiB 2 NaB 9

GC 3 MgC 10

BoD 4 AlD 11

CE 5 SiE 12

NF 6 PF 13

OG 7 SG 14

1 o

ctav

e

Elements with similar propertiesare in the same row

and so on

Figure 6-3

Dmitri Mendeleev produced thefirst useful and widely acceptedperiodic table. The monumentshown on the right is located inSt. Petersburg, Russia, and showsan early version of Mendeleev’speriodic table. The blank areason the table show the positionsof elements that had not yetbeen discovered.

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Figure Caption QuestionFigure 6-2 What similarities anddifferences can you identify? similarities: elements arranged ingroups with repeating properties;properties repeat every eightelements (elements with atomicnumbers � 20) differences: columns and rowsare interchanged; element namesdiffer

Visual LearningVisual-Spatial Have yourclass create a classroom peri-

odic table that describes the char-acteristics of each of the students.Each student will be a cell in theclassroom periodic table. Provideeach student with a one-foot squareposter board. In the center of thesquare, each student should writehis or her two-letter student symbol(capped initial of last namefollowed by lower-case initial offirst name). Pick student-basedcharacteristics such as shoe size,hair color, sports interest, favoriteschool subject, etc. Define a loca-tion on the card for each character-istic. Have each student completehis or her card; then, have the classdetermine an appropriate methodfor organizing the squares, so that,if possible, a periodic pattern isdeveloped.

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Quick Demo

Randomly display about 30 stock bottles of elementsand compounds. Ask studentswhether such an arrangementfacilitates being able to locatea particular substance. Havestudents suggest better ways toarrange the substances.

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Intrapersonal Mendeleev predictedproperties of several elements that had

not been discovered at the time he pub-lished his periodic table. Provide studentswith several of the properties he predictedand have them research the properties ofthe actual element that was discovered. Oneexample is ekasilicon, which was named gal-lium once it was discovered.

Mendeleev predicted that ekasilicon wouldhave an atomic mass of 68 amu, a low meltingpoint, a density of 5.9 g/cm3, and an oxide formula of Ea2O3. Have students research theactual properties of gallium and evaluate howclose Mendeleev’s predictions were to theactual properties. Ask students what theythink the prefix eka- means.

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Gifted

The periodic table became a significant tool for chemists working in the newindustries created during the industrial revolution. The table brought order toseemingly unrelated facts. You, too, will find the periodic table a valuable tool.Among other things, it is a useful reference for understanding and predictingthe properties of elements and for organizing your knowledge of atomic struc-ture. Do the problem-solving LAB on the next page to see how the periodiclaw can be used to predict unknown elemental properties.

The Modern Periodic TableThe modern periodic table is shown in Figure 6-4 and on the inside backcover of your textbook. A larger, two-page version of the table appears inFigure 6-7 on pages 156-157. The table consists of boxes, each containingan element name, symbol, atomic number, and atomic mass. A typical boxfrom the table is shown in Figure 6-5. The boxes are arranged in order ofincreasing atomic number into a series of columns, called groups or fami-lies, and rows, called periods. Beginning with hydrogen in period 1, thereare a total of seven periods. Each group is numbered 1 through 8, followedby the letter A or B. For example, scandium (Sc) is in the third column fromthe left, group 3B. What group is oxygen in? What period contains potas-sium and calcium? The groups designated with an A (1A through 8A) areoften referred to as the main group, or representative elements because theypossess a wide range of chemical and physical properties. The groups des-ignated with a B (1B through 8B) are referred to as the transition elements.A more recent numbering system, which uses the numbers 1 through 18, alsoappears above each group. The number-and-letter system is used through-out this textbook.


Figure 6-4

The modern periodic tablearranges the elements byincreasing atomic number. Thecolumns are known as groups orfamilies, and the rows areknown as periods.

PERIODIC TABLE OF THE ELEMENTS

Hydrogen

1

H

1.008

Element

Atomic number

Symbol

Atomic mass

State ofmatter

Metal

Metalloid

Nonmetal

Recently discovered

Gas

Liquid

Solid

Synthetic

Hydrogen

1

H1.008

Helium

2

He4.003

Lithium

3

Li6.941

Sodium

11

Na22.990

Potassium

19

K39.098

Rubidium

37

Rb85.468

Cesium

55

Cs132.905

Francium

87

Fr(223)

Radium

88

Ra(226)

Cerium

58

Ce140.116

Thorium

90

Th232.038

Uranium

92

U238.029

Neptunium

93

Np(237)

Plutonium

94

Pu(244)

Americium

95

Am (243)

Curium

96

Cm(247)

Berkelium

97

Bk(247)

Californium

98

Cf(251)

Einsteinium

99

Es(252)

Fermium

100

Fm(257)

Nobelium

102

No(259)

Lawrencium

103

Lr(262)

Mendelevium

101

Md(258)

Neodymium

60

Nd144.24

Promethium

61

Pm(145)

Samarium

62

Sm150.36

Europium

63

Eu151.964

Gadolinium

64

Gd157.25

Terbium

65

Tb158.925

Dysprosium

66

Dy162.50

Holmium

67

Ho164.930

Erbium

68

Er167.259

Thulium

69

Tm168.934

Ytterbium

70

Yb173.04

Lutetium

71

Lu174.967

Praseodymium

59

Pr140.908

Protactinium

91

Pa231.036

Actinium

89

Ac(227)

Rutherfordium

104

Rf(261)

Barium

56

Ba137.327

Lanthanum

57

La138.906

Hafnium

72

Hf178.49

Tantalum

73

Ta180.948

Dubnium

105

Db(262)

Seaborgium

106

Sg(266)

Hassium

108

Hs(277)

Meitnerium

109

Mt(268)

Ununnilium

110

Uun(281)

Unununium

111

Uuu(272)

Ununbium

112

Uub(285)

Ununquadium

114

Uuq(289)

Ununhexium

116

Uuh(289)

Ununoctium

118

Uuo(293)

Bohrium

107

Bh(264)

Tungsten

74

W183.84

Rhenium

75

Re186.207

Osmium

76

Os190.23

Iridium

77

Ir192.217

Platinum

78

Pt195.078

Gold

79

Au196.967

Mercury

80

Hg200.59

Thallium

81

Tl204.383

Lead

82

Pb207.2

Bismuth

83

Bi208.980

Astatine

85

At(210)

Radon

86

Rn(222)

Strontium

38

Sr87.62

Yttrium

39

Y88.906

Zirconium

40

Zr91.224

Niobium

41

Nb92.906

Molybdenum

42

Mo95.94

Calcium

20

Ca40.078

Scandium

21

Sc44.956

Titanium

22

Ti47.867

Vanadium

23

V50.942

Chromium

24

Cr51.996

Technetium

43

Tc(98)

Ruthenium

44

Ru101.07

Manganese

25

Mn54.938

Iron

26

Fe55.845

Cobalt

27

Co58.933

Nickel

28

Ni58.693

Copper

29

Cu63.546

Zinc

30

Zn65.39

Gallium

31

Ga69.723

Germanium

32

Ge72.64

Arsenic

33

As74.922

Selenium

34

Se78.96

Bromine

35

Br79.904

Krypton

36

Kr83.80

Rhodium

45

Rh102.906

Palladium

46

Pd106.42

Silver

47

Ag107.868

Cadmium

48

Cd112.411

Indium

49

In114.818

Tin

50

Sn118.710

Antimony

51

Sb121.760

Tellurium

52

Te127.60

Iodine

53

I126.904

Xenon

54

Xe131.293

Magnesium

12

Mg24.305

Aluminum

13

Al26.982

Silicon

14

Si28.086

Phosphorus

15

P30.974

Sulfur

16

S32.065

Chlorine

17

Cl35.453

Argon

18

Ar39.948

Beryllium

4

Be9.012

Boron

5

B10.811

Carbon

6

C12.011

Nitrogen

7

N14.007

Oxygen

8

O15.999

Fluorine

9

F18.998

Neon

10

Ne20.180

Lanthanide series

Actinide series

1A1

12A2

2

3

4

5

6

7

9 101B11

2B12

3A13

4A14

5A15

6A16

7A17

8A18

3B3

4B4

5B5

6B6

7B7

Polonium

84

Po(209)

Names not officially assigned. Discovery of elements 114, 116, and 118 recently reported. Further information not yet available.*

* * * * * *

8B8

The number in parentheses is the mass number of the longest lived isotope for that element.

Visit the Chemistry Web site atscience.glencoe.com to find updates on the periodic table.

Figure 6-5

A typical box from the periodictable contains important infor-mation about an element.

Oxygen

8

O15.999

ElementState ofmatterAtomicmass

AtomicnumberSymbol

154

Visual LearningVisual-Spatial Providestudents with a list of element

names and their dates of discovery,or have students research thesedates. Give each student a set of colored pencils and a basic periodic table that contains onlyelement names or symbols. Have students color each of thefollowing sets of elements adifferent color.• elements known by the year 100• elements discovered from 101

to 1600• elements discovered from 1601

to 1799• elements discovered from 1800

through the time Mendeleevpublished his first periodic table(�1870)

• elements discovered from 1871 to 1980

• elements discovered since 1981

In-Text QuestionsPage 154 What group is oxygenin? 6A What period contains potas-sium and calcium? 4

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Pages 154–1552(D), 2(E), 3(A), 3(E), 4(D), 6(C)

International TablesCollect periodic tables from a variety ofcountries, such as Japan, Russia, Germany,Spain, and Mexico. Display these periodictables and have students examine them forsimilarities and differences. For example, aJapanese periodic table uses the same sym-bol (Na) for sodium as an English table, butthe element name is written in Kanji or

Japanese calligraphy. If time permits, havestudents further investigate how the Englishtranslation for the element name comparesto the English name for the element. Whilethere are alternative forms of the periodictable, students will find that the shape ofthe periodic table is relatively universal.P

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Classifying the elements There are three main classifications for the ele-ments—metals, nonmetals, and metalloids. Metals are elements that are gen-erally shiny when smooth and clean, solid at room temperature, and goodconductors of heat and electricity. Most metals also are ductile and malleable,meaning that they can be pounded into thin sheets and drawn into wires,respectively. Figure 6-6 shows several applications that make use of thephysical properties of metals.

Most group A elements and all group B elements are metals. If you lookat boron (B) in column 3A, you see a heavy stair-step line that zigzags downto astatine (At) at the bottom of group 7A. This stair-step line serves as a visualdivider between the metals and the nonmetals on the table. Metals are repre-sented by the light blue boxes in Figure 6-7. Except for hydrogen, all of theelements on the left side of the table are metals. The group 1A elements(except for hydrogen) are known as the alkali metals; the group 2A elementsare known as the alkaline earth metals. Both the alkali metals and the alka-line earth metals are chemically reactive, with the alkali metals being the morereactive of the two groups.


problem-solving LAB

Francium—solid, liquid or gas?Predicting Of the first 101 elements, franciumis the least stable. Its most stable isotope has ahalf-life of just 22 minutes! Use your knowledgeabout the properties of other alkali metals topredict some of francium’s properties.

AnalysisIn the spirit of Dimitri Mendeleev’s prediction ofthe properties of several, as of then, undiscov-ered elements, use the given information aboutthe known properties of the alkali metals todevise a method for determining the correspon-ding property of francium.

Thinking Critically1. Using the periodic law as a guide, devise an

approach that clearly displays the trends foreach of the properties given in the table andallows you to extrapolate a value for francium.

2. Predict whether francium is a solid, liquid, orgas. How can you support your prediction?

3. Which of the given columns of data presentsthe greatest possible error in making a predic-tion? Explain.

4. Currently, scientists can produce about onemillion francium atoms per second. Explainwhy this is still not enough to make basicmeasurements such as density or meltingpoint.

Figure 6-6

Metals are used in a wide vari-ety of applications. The excellentelectrical conductivity of metalssuch as copper, makes them agood choice for transmittingelectrical power. Ductility andmalleability allow metals to beformed into coins, tools, fast-ners, and wires.

Alkali Metals Data

Melting Boiling RadiusElement point (°C) point (°C) (pm)

lithium 180.5 1347 152

sodium 97.8 897 186

potassium 63.3 766 227

rubidium 39.31 688 248

cesium 28.4 674.8 265

francium ? ? ?

Purpose Students will use the periodic law to determine the melting point,boiling point, and heat of vaporization of francium.

Process SkillsPredicting, identifying variables,making and using graphs, inter-preting data, observing and inferring, applying concepts

Teaching Strategies• Review the periodic law and ask

students how the law can be usedto predict the melting point,boiling point, and heat of vapor-ization of francium. By plotting agraph of these properties versusatomic number for the knownalkali metals, francium’s valuescan be extrapolated from thegraph.

• Explain why there is so little francium in Earth’s crust.Francium-223 is the only natu-rally occurring isotope of theelement. It is produced fromthe alpha decay of actinium-227, which itself is producedfrom the decay of uranium-238.For one ton of U-238, only 0.2 mg of Ac-227 is formed. Ac-227, with a half-life of 22 years, produces only 3.8 � 10�10 g of Fr-223. Theunstable Fr-223 decays veryquickly, having a half-life ofonly 22 minutes.

Thinking Critically1. A graph of each property

versus atomic number is thebest approach. See theSolutions Manual. Byextending the data curvethrough to francium’s atomicnumber of 87, its radius,melting point, and boilingpoint can be determined. R � 280–290 pm, MP � 25°C,and BP � 675°C.

2. Francium is probably a liquidat room temperature. Itsmelting point is probablybelow 20°C, according to thetrend shown in the table.

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3. The radius prediction is most inaccurate.The affect of the principal energy level onthe radius is harder to extrapolate accu-rately because it varies from period toperiod.

4. Even one million atoms collected togetheras a solid are microscopic. A grain of saltcontains about 1015 sodium atoms.

Performance Give students anothercharacteristic property, such as heat of vapor-ization, and have them predict francium’svalue. Use the Performance Task AssessmentList for Making Observations and Inferencesin PASC, p. 17. L2

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AssessmentAssessment


PERIODIC TABLE OF THE ELEMENTS

Hydrogen

1

H

1.008

Element

Atomic number

Symbol

Atomic mass

State ofmatter

Gas

Liquid

Solid

Synthetic

Hydrogen

1

H1.008

Lithium

3

Li6.941

Sodium

11

Na22.990

Potassium

19

K39.098

Rubidium

37

Rb85.468

Cesium

55

Cs132.905

Francium

87

Fr(223)

Radium

88

Ra(226)

Cerium

58

Ce140.116

Thorium

90

Th232.038

Uranium

92

U238.029

Neptunium

93

Np(237)

Plutonium

94

Pu(244)

Americium

95

Am (243)

Neodymium

60

Nd144.24

Promethium

61

Pm(145)

Samarium

62

Sm150.36

Europium

63

Eu151.964

Praseodymium

59

Pr140.908

Protactinium

91

Pa231.036

Actinium

89

Ac(227)

Rutherfordium

104

Rf(261)

Barium

56

Ba137.327

Lanthanum

57

La138.906

Hafnium

72

Hf178.49

Tantalum

73

Ta180.948

Dubnium

105

Db(262)

Seaborgium

106

Sg(266)

Hassium

108

Hs(277)

Meitnerium

109

Mt(268)

Bohrium

107

Bh(264)

Tungsten

74

W183.84

Rhenium

75

Re186.207

Osmium

76

Os190.23

Iridium

77

Ir192.217

Strontium

38

Sr87.62

Yttrium

39

Y88.906

Zirconium

40

Zr91.224

Niobium

41

Nb92.906

Molybdenum

42

Mo95.94

Calcium

20

Ca40.078

Scandium

21

Sc44.956

Titanium

22

Ti47.867

Vanadium

23

V50.942

Chromium

24

Cr51.996

Technetium

43

Tc(98)

Ruthenium

44

Ru101.07

Manganese

25

Mn54.938

Iron

26

Fe55.845

Cobalt

27

Co58.933

Rhodium

45

Rh102.906

Magnesium

12

Mg24.305

Beryllium

4

Be9.012

Lanthanide series

Actinide series

1A1

12A2

2

3

4

5

6

7

93B3

4B4

5B5

6B6

7B7

8B8

The number in parentheses is the mass number of the longest lived isotope for that element.

Figure 6-7

156

Knowledge Point out thatthe placement of several pairs ofelements on Mendeleev’s tablewere incorrect. Argon and potas-sium are one pair whose correctpositions were reversed. Askstudents to suggest reasons whyMendeleev used atomic massinstead atomic number to organizethe elements. The property ofatomic number was not discov-ered until the early 1900s, thus making it impossible forMendeleev to base his periodictable on it. L2

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Kinesthetic Have students create adot-to-dot puzzle using chemical sym-

bols as clues. Draw the outline of a piece oflab equipment, a lab setup, or some otherchemistry-related picture using a dark felttip marker. Place another sheet of paperover the first and mark dots along the

image, especially at critical directionchanges. Label the dots with chemical sym-bols instead of by number. The atomic num-ber of each chemical symbol represents thenumber of each dot (H is 1, He is 2, Li is 3,etc.). Students should exchange and com-plete each other’s puzzles.

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CD-ROMChemistry: Matter and Change

Exploration: The Periodic TableVideo: Transuranium ElementsDemonstration: Activity ofAlkali Metals


Metal

Metalloid

Nonmetal

Recently discovered

Helium

2

He4.003

Curium

96

Cm(247)

Berkelium

97

Bk(247)

Californium

98

Cf(251)

Einsteinium

99

Es(252)

Fermium

100

Fm(257)

Nobelium

102

No(259)

Lawrencium

103

Lr(262)

Mendelevium

101

Md(258)

Gadolinium

64

Gd157.25

Terbium

65

Tb158.925

Dysprosium

66

Dy162.50

Holmium

67

Ho164.930

Erbium

68

Er167.259

Thulium

69

Tm168.934

Ytterbium

70

Yb173.04

Lutetium

71

Lu174.967

Ununnilium

110

Uun(281)

Unununium

111

Uuu(272)

Ununbium

112

Uub(285)

Ununquadium

114

Uuq(289)

Ununhexium

116

Uuh(289)

Ununoctium

118

Uuo(293)

Platinum

78

Pt195.078

Gold

79

Au196.967

Mercury

80

Hg200.59

Thallium

81

Tl204.383

Lead

82

Pb207.2

Bismuth

83

Bi208.980

Astatine

85

At(210)

Radon

86

Rn(222)

Nickel

28

Ni58.693

Copper

29

Cu63.546

Zinc

30

Zn65.39

Gallium

31

Ga69.723

Germanium

32

Ge72.64

Arsenic

33

As74.922

Selenium

34

Se78.96

Bromine

35

Br79.904

Krypton

36

Kr83.80

Palladium

46

Pd106.42

Silver

47

Ag107.868

Cadmium

48

Cd112.411

Indium

49

In114.818

Tin

50

Sn118.710

Antimony

51

Sb121.760

Tellurium

52

Te127.60

Iodine

53

I126.904

Xenon

54

Xe131.293

Aluminum

13

Al26.982

Silicon

14

Si28.086

Phosphorus

15

P30.974

Sulfur

16

S32.065

Chlorine

17

Cl35.453

Argon

18

Ar39.948

Boron

5

B10.811

Carbon

6

C12.011

Nitrogen

7

N14.007

Oxygen

8

O15.999

Fluorine

9

F18.998

Neon

10

Ne20.180

101B11

2B12

3A13

4A14

5A15

6A16

7A17

8A18

Polonium

84

Po(209)

Names not officially assigned. Discovery of elements 114, 116, and 118 recently reported. Further information not yet available.*

* * * * * *

Visit the Chemistry Web site atscience.glencoe.com to find updates on the periodic table.

157

Applying ChemistryGemstones often owetheir color to atoms oftransition elements thatare substituted into acrystal structure. For

example, consider the mineralcorundum (Al2O3). If chromiumatoms replace a few aluminumatoms in the crystal structure, theresulting crystal has a brilliant redcolor. This crystal is the gemstoneknown as a ruby. The substitutionof iron atoms results in thegemstone known as topaz. Thesubstitution of titanium atomsresults in a sapphire. Anotherexample occurs in the mineralknown as beryl (Be3Al2Si6O18). If afew of the aluminum atoms in thecrystal are replaced with chromiumatoms, the result is a brilliant greenemerald. The substitution of oneatom for another occurs becausethe atoms have similar atomic radiiand valence electrons.

Pages 156–1572(D), 4(D)

CHEMISTRY JOURNAL CHEMISTRY JOURNAL

Student News CorrespondentsInterpersonal Have students pretendthey are newspaper reporters and their

assignment is to interview Mendeleev andMoseley. They should conduct some back-ground research in order to be effectivereporters. In addition to asking about their

subjects’ respective chemical discoveries, sug-gest that some of the interview questionsrelate to the subjects’ experiences during thetime period in which they lived, their educa-tional backgrounds, and the countries inwhich they lived.

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VIDEODISCCosmic ChemistryDisc 3, Side 6

Still: Periodic Table; metals andnonmetals

{`@≤A—}


3 AssessCheck for Understanding

Linguistic Have studentswrite a paragraph using each

of the vocabulary words listed forthe section.

ReteachInterpersonal Pair students.Have one student select an

element that the other student mustclassify using the terms introducedin this section. Have studentsreverse roles so that both studentshave the opportunity to respond.

ExtensionHave students predict the proper-ties for element 117. They shouldoffer supporting reasons for theirpredictions.

Skill Display samples ofelements that represent metals,nonmetals, and metalloids. Havestudents record their observationsof each sample and classify it as ametal, nonmetal, or metalloid. Ifpossible, students should identifyeach element and state its group.L2

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Section Assessment6.1

1. Newlands was the first to organizethe elements and show that proper-ties repeated in a periodic way.Mendeleev and Meyer proposedperiodic tables showing a relation-ship between atomic mass andelemental properties. Moseley orga-

nized the elements by atomicnumber instead of atomic mass.

2. Simplified tables should resembleFigure 6-7 with the groups andperiods labeled. See the SolutionsManual.

3. metals: shiny, ductile, malleable,good conductors of heat and elec-tricity; nonmetals: dull, brittle, poor

conductors of heat and electricity;metalloids: properties midwaybetween metals and nonmetals

4. a. representative; b. transition; c. transition; d. representative

5. a. any other group 7A element; b. any other group 2A element; c. any other group 8B element

6. germanium (Ge)158

CHEMLAB

The group B elements, or transition ele-ments, are divided into transition metals andinner transition metals. The two sets of innertransition metals, known as the lanthanide andactinide series, are located along the bottom ofthe periodic table. The rest of the group B ele-ments make up the transition metals. Elementsfrom the lanthanide series are used extensivelyas phosphors, substances that emit light whenstruck by electrons. The How It Works at theend of the chapter explains more about phos-phors and how images are formed on a televi-sion screen.

Nonmetals occupy the upper right side ofthe periodic table. They are represented by theyellow boxes in Figure 6-7. Nonmetals areelements that are generally gases or brittle,dull-looking solids. They are poor conductorsof heat and electricity. The only nonmetal thatis a liquid at room temperature is bromine (Br).The highly reactive group 7A elements areknown as halogens, and the extremely unre-active group 8A elements are commonly calledthe noble gases.

Examine the elements in green boxes bordering the stair-step line inFigure 6-7. These elements are called metalloids, or semimetals. Metalloidsare elements with physical and chemical properties of both metals and non-metals. Silicon and germanium are two of the most important metalloids, asthey are used extensively in computer chips and solar cells. Applications thatmake use of the properties of nonmetals, transition metals, and metalloidsare shown in Figure 6-8. Do the CHEMLAB at the end of this chapter toobserve trends among various elements.

This introduction to the periodic table only touches the surface of its usefulness. In the next section, you will discover how an element’s electronconfiguration, which you learned about in Chapter 5, is related to its positionon the periodic table.


Figure 6-8

A mountain climber breathesfrom a container of compressedoxygen gas, a nonmetal. ThisPersian brass bowl containsinlays of the transition metalssilver and gold. Silicon crys-tals, a metalloid, are grown inan inert atmosphere of argon, anonmetal. The crystals are usedin the manufacture of computerchips.

c

b

a

Section 6.1 Assessment

1. Describe the development of the modern periodictable. Include contributions made by Newlands,Mendeleev, and Moseley.

2. Sketch a simplified version of the periodic tableand indicate the location of groups, periods, metals,nonmetals, and metalloids.

3. Describe the general characteristics of metals, non-metals, and metalloids.

4. Identify each of the following as a representativeelement or a transition element.a. lithium (Li) c. promethium (Pm)b. platinum (Pt) d. carbon (C)

5. Thinking Critically For each of the given ele-ments, list two other elements with similar chemi-cal properties.a. iodine (I)b. barium (Ba)c. iron (Fe)

6. Interpreting Data An unknown element haschemical behavior similar to that of silicon (Si) andlead (Pb). The unknown element has a mass greaterthan that of sulfur (S), but less than that of cad-mium (Cd). Use the periodic table to determine theidentity of the unknown element.

a

b

c

ChemLab 6, located at the end ofthe chapter, can be used at thispoint in the lesson.

159

1 Focus


2 TeachConcept DevelopmentEmphasize that electron configura-tion is a periodic trend and that itdetermines an element’s chemicalproperties.

In-Text QuestionPage 159 What is the electronconfiguration for the group 1Aelement in the sixth period? [Xe]6s1

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6.2 Classification of the Elements 159

Objectives• Explain why elements in the

same group have similarproperties.

• Identify the four blocks ofthe periodic table based onelectron configuration.

Section Classification of the Elements

In Chapter 5, you learned how to write the electron configuration for an atom.This is an important skill because the electron configuration determines thechemical properties of the element. However, the process of writing out elec-tron configurations using the aufbau diagram can be tedious. Fortunately, bynoting an atom’s position on the periodic table, you can determine its electronconfiguration and its number of valence electrons.

Organizing the Elements by ElectronConfigurationTake a look at the electron configurations for the group 1A elements listedbelow. These elements comprise the first four periods of group 1A.

Period 1 hydrogen 1s1 1s1

Period 2 lithium 1s22s1 [He]2s1

Period 3 sodium 1s22s22p63s1 [Ne]3s1

Period 4 potassium 1s22s22p63s23p64s1 [Ar]4s1

What do the four configurations have in common? The answer is that theyall have a single electron in their outermost energy level.

Valence electrons Recall from Chapter 5 that electrons in the highest prin-cipal energy level of an atom are called valence electrons. Each of the group1A elements has one electron in its highest energy level; thus, each elementhas one valence electron. This is no coincidence. The group 1A elements havesimilar chemical properties because they all have the same number of valenceelectrons. This is one of the most important relationships in chemistry; atomsin the same group have similar chemical properties because they have the samenumber of valence electrons. Each group 1A element has a valence electronconfiguration of s1. Likewise, each group 2A element has a valence electronconfiguration of s2. Each column of group A elements on the periodic tablehas its own unique valence electron configuration.

Valence electrons and period The energy level of an element’s valenceelectrons indicates the period on the periodic table in which it is found. Forexample, lithium’s valence electron is in the second energy level and lithiumis found in period 2. Now look at gallium, with its electron configuration of[Ar]4s23d104p1. Gallium’s valence electrons are in the fourth energy level, andgallium is found in the fourth period. What is the electron configuration forthe group 1A element in the sixth period?

Valence electrons and group number A representative element’s groupnumber and the number of valence electrons it contains also are related.Group 1A elements have one valence electron, group 2A elements have twovalence electrons, and so on. There are several exceptions to this rule, how-ever. The noble gases in group 8A each have eight valence electrons, with theexception of helium, which has only two valence electrons. Also, the groupnumber rule applies only to the representative elements (the group A ele-ments). See Figure 6-9 on the next page. The electron-dot structures youlearned in Chapter 5 illustrate the connection between group number andnumber of valence electrons.

6.2

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Section Focus Transparency 21 CyclesUse with Chapter 6, Section 6.2



What cycle do the photographs illustrate?What should the missing photograph in the cycle show?

How do you know this?

1

2

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PortfolioPortfolio

Visual-Spatial Have students create atime line that includes all of the peo-

ple discussed in Chapters 5 and 6 and theircontributions to chemistry. Students shouldthen pick another topic, such as famous

inventions, to plot on the time line. Havethem compare the events on the time lineand look for ways in which they may berelated. They should place the time lines intheir portfolios.

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Time Line Comparisons

CD-ROMChemistry: Matter and Change

Experiment: Classify the Elements

Pages 158–1613(D), 3(E), 4(C), 4(D), 6(A)

The s-, p-, d-, and f-Block ElementsThe periodic table has columns and rows of varying sizes. The reason behindthe table’s odd shape becomes clear if it is divided into sections, or blocks,representing the atom’s energy sublevel being filled with valence electrons.Because there are four different energy sublevels (s, p, d, and f), the periodictable is divided into four distinct blocks, as shown in Figure 6-10.

s-block elements The s-block consists of groups 1A and 2A, and the ele-ments hydrogen and helium. In this block, the valence electrons, representedin Figure 6-9, occupy only s orbitals. Group 1A elements have partially filleds orbitals containing one valence electron and electron configurations endingin s1. Group 2A elements have completely filled s orbitals containing twovalence electrons and electron configurations ending in s2. Because s orbitalshold a maximum of two electrons, the s-block portion of the periodic tablespans two groups.

p-block elements After the s sublevel is filled, the valence electrons,represented in Figure 6-9, next occupy the p sublevel and its three p orbitals. The p-block of the periodic table, comprised of groups 3Athrough 8A, contains elements with filled or partially filled p orbitals.Why are there no p-block elements in period 1? The answer is that the psublevel does not exist for the first principal energy level (n = 1). Thus,the first p-block element is boron (B), in the second period. The p-blockspans six groups on the periodic table because the three p orbitals can holda maximum of six electrons. Together, the s- and p-blocks comprise therepresentative, or group A, elements.

The group 8A, or noble gas, elements are unique members of the p-blockbecause of their incredible stability. Noble gas atoms are so stable that theyundergo virtually no chemical reactions. The reason for their stability lies intheir electron configurations. Look at the electron configurations of the firstfour noble gas elements shown in Table 6-1. Notice that both the s and porbitals corresponding to the period’s principal energy level are completelyfilled. This arrangement of electrons results in an unusually stable atomicstructure. You soon will learn that this stable configuration plays an importantrole in the formation of ions and chemical bonds.

d-block elements The d-block contains thetransition metals and is the largest of theblocks. Although there are a number ofexceptions, d-block elements are character-ized by a filled outermost s orbital of energylevel n, and filled or partially filled d orbitalsof energy level n – 1. As you move across theperiod, electrons fill the d orbitals. For exam-ple, scandium (Sc), the first d-block element,has an electron configuration of [Ar]4s23d1.Titanium, the next element on the table, hasan electron configuration of [Ar]4s23d2. Notethat titanium’s filled outermost s orbital hasan energy level of n = 4, while the partiallyfilled d orbital has an energy level of n – 1, or 3. The five d orbitals can hold a totalof ten electrons; thus, the d-block spans tengroups on the periodic table.


Ba

Ca

Mg Si

Ga

Ar

Kr

Xe

He

Cl

Br

SP

As

Sb

Se

Te

Ge

SnIn

RnPoBiPbTl

Al

Sr

Na

H

K

Rb

Cs

Be NeONCBLi F

I

1A1

8A18

1

2

3

4

5

6

2A1

3A13

4A14

5A15

6A16

7A17

Figure 6-9

The electron-dot structures ofmost of the representative ele-ments are shown here. The number of valence electrons isthe same for all members of agroup. For the group A ele-ments, an atom’s number ofvalence electrons is equal to its group number (in the 1A, 2A, . . . numbering system).

Medical Lab TechnicianWould you like to analyzeblood and tissue samples? Howabout determining the chemi-cal content of body fluids? Ifso, you might enjoy being amedical lab technician.

Medical or clinical lab techni-cians work in large hospitalsor independent labs. Underthe direction of a technolo-gist, they prepare specimens,conduct tests, and operatecomputerized analyzers.Technicians need to pay closeattention to detail, have goodjudgement, and be skilled inusing computers.

160

Career Path A career inmedical lab technologywould include high schoolcourses in chemistry,biology, computer science,

and math. Most lab technicians havea two-year degree or a certificatefrom a program in medical tech-nology. A few receive only on-the-job training. Some states requirelicensing or registration.Career Issue Ask students toname some pressures that a technician might face in a hospital laboratory.

For More Information For more information about careersin medical lab technology, studentscan contact

National Association of Health Career Schools

2301 Academy DriveHarrisburg, PA 17112

Figure Caption QuestionFigure 6-10 What is the relation-ship between the maximumnumber of electrons an energysublevel can hold and the size ofthat block on the diagram? themaximum number of electrons ina sublevel equals the number ofcolumns spanned by the block

CAREERS USING CHEMISTRY


Kinesthetic Assign each student a representative element. Have them

construct a three-dimensional cube usingposter board and artistically label one sideof the cube with the name of the element.Another side of the cube should show theelement’s group, while another side provides

the element’s electron configuration. Theyshould use the remaining sides to illustrateproperties of the element, its uses, and someof its important compounds. Hang thesecubes from the ceiling in the classroom.

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Hearing Impaired


Study Guide for Content Mastery, pp. 33–34

Challenge Problems, p. 6 Solving Problems: A Chemistry Handbook, Section 6.2


Teaching Transparency 19 and Master

Math Skills Transparency 6 and Master,

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6.2 Classification of the Elements 161

f-block elements The f-block contains the inner transition metals. The f-block elements are characterized by a filled, or partially filled outermost s orbital, and filled or partially filled 4f and 5f orbitals. The electrons of thef sublevel do not fill their orbitals in a predictable manner. Because there areseven f orbitals holding up to a maximum of 14 electrons, the f-block spans14 columns of the periodic table.

Thus, the s-, p-, d-, and f-blocks determine the shape of the periodic table.As you proceed down through the periods, the principal energy level increases,as does the number of energy sublevels containing electrons. Period 1 con-tains only s-block elements, periods 2 and 3 contain both s- and p-block ele-ments, periods 4 and 5 contain s-, p-, and d-block elements, and periods 6and 7 contain s-, p-, d-, and f-block elements.

Figure 6-10

Although electrons fill theorbitals of s- and p-block ele-ments in a predictable manner,there are a number of excep-tions in the d- and f-block elements. What is the relation-ship between the maximumnumber of electrons an energysublevel can hold and the size ofthat block on the diagram?

s1

1H

2He

3Li

11Na

19K

37Rb

55Cs

4Be

12Mg

20Ca

38Sr

56Ba

87Fr

58Ce

90Th

59Pr

91Pa

60Nd

92U

61Pm

93Np

62Sm

94Pu

63Eu

95Am

64Gd

96Cm

65Tb

97Bk

66Dy

98Cf

67Ho

99Es

68Er

100Fm

69Tm

101Md

70Yb

102No

71Lu

103Lr

88Ra

5B

13Al

31Ga

49In

81Tl

6C

14Si

32Ge

50Sn

82Pb

7N

15P

33As

51Sb

83Bi

8O

16S

34Se

52Te

84Po

9F

17Cl

35Br

53I

85At

10Ne

18Ar

36Kr

54Xe

86Rn

21Sc

39Y

57La

89Ac

22Ti

40Zr

72Hf

104Rf

23V

41Nb

73Ta

105Db

24Cr

42Mo

74W

106Sg

25Mn

43Tc

75Re

107Bh

26Fe

44Ru

76Os

108Hs

27Co

45Rh

77Ir

109Mt

110Uun

28Ni

46Pd

78Pt

111Uuu

29Cu

47Ag

79Au

112Uub

30Zn

48Cd

80Hg

s2 p1 p2 p3 p4 p5 p6

s2

s block

d block

p block

f block

Electron Configurations of Helium, Neon, Argon, and Krypton

Period Principal Element Electron Electron dotenergy level configuration structure

1 n = 1 helium 1s2

2 n = 2 neon [He]2s22p6

3 n = 3 argon [Ne]3s23p6

4 n = 4 krypton [Ar]4s23d104p6

Table 6-1

He

Ne

Ar

Kr

161

Portfolio Both helium and beryllium have two valenceelectrons. One of the elements isrelatively reactive; the other isnonreactive. Have students explainthe difference in chemical reac-tivity in spite of the similar electron configurations. The explanations should be placed inthe students’ portfolios. PP

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Quick Demo

Kinesthetic Demonstrateto the class the malle-

ability of several differentmetals. Using similar thick-nesses of sheets of copper, tin,lead, and iron, have studentvolunteers test and comparethe malleability with ahammer. CAUTION: Studentsshould wear safety gogglesand be instructed on the safeuse of the hammers. Havestudents rank the metals inorder of decreasingmalleability.

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Applying ChemistryStudents may wonder whyscientists continue tryingto produce new syntheticelements. Part of thereason is for the sake of

research itself, but occasionally the newly synthesized radioactiveelements do find commercial appli-cations. One example is americium,element 95, discovered in 1944.Americium is used in smoke alarmsand other high-precision measuringdevices. Scientists are also hopingthat element 96, curium, couldeventually have commercial appli-cations as a small, portable, powergenerator.

3 AssessCheck for Understanding

Visual-Spatial Give blankperiodic tables to students

and have them label the periods,groups, and blocks.

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CHEMISTRY JOURNAL CHEMISTRY JOURNAL

Noble GasesLinguistic Ask students to researchhow and when the noble gases were

discovered. They should also research theuses of noble gases, their relative reactivi-ties, and if they form any compounds.

Students should write a paragraph describ-ing why the noble gases belong on the farright-hand side of the periodic table. Havethem add their research and paragraphs totheir portfolios.

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10. Explain why elements in the same group on theperiodic table have similar chemical properties.

11. Given each of the following valence electron con-figurations, determine which block of the periodictable the element is in.a. s2p4 b. s1 c. s2d1 d. s2p1

12. Describe how each of the following are related.a. Group number and number of valence electrons

for representative elementsb. Principal energy level of valence electrons and

period number

13. Without using the periodic table, determine thegroup, period, and block of an atom with an elec-tron configuration of [Ne]3s23p4.

14. Thinking Critically A gaseous element is a poorconductor of heat and electricity, and is extremelynonreactive. Is the element likely to be a metal,nonmetal, or metalloid? Where would the elementbe located on the periodic table? Explain.

15. Formulating Models Make a simplified sketchof the periodic table and label the s-, p-, d-, and f-blocks.

EXAMPLE PROBLEM 6-1

Electron Configuration and the Periodic TableStrontium has an electron configuration of [Kr]5s2. Without using theperiodic table, determine the group, period, and block in which stron-tium is located on the periodic table.

1. Analyze the ProblemYou are given the electron configuration of strontium. The energylevel of the valence electrons can be used to determine the period inwhich strontium is located. The electron configuration of the valenceelectrons can be used to determine the group and the block in whichstrontium is located.

2. Solve for the UnknownGroup The valence electron configuration of s2 indicates that stron-tium is in group 2A. All group 2A elements have the s2 configuration.Period The 5 in 5s2 indicates that strontium is in period 5. Block The s2 indicates that strontium’s valence electrons fill the ssublevel. Thus, strontium is in the s-block.

3. Evaluate the AnswerThe relationships among electron configuration and position on theperiodic table have been correctly applied. The given informationidentifies a unique position on the table, as it must.

PRACTICE PROBLEMS7. Without using the periodic table, determine the group, period, and

block of an atom with the following electron configurations.a. [Ne]3s2 b. [He]2s2 c. [Kr]5s24d105p5

8. Write the electron configuration of the element fitting each of thefollowing descriptions. a. The group 2A element in the fourth periodb. The noble gas in the fifth periodc. The group 2B element in the fourth periodd. The group 6A element in the second period

9. What are the symbols for the elements with the following valenceelectron configurations?a. s2d1 b. s2p3 c. s2p6

For more practice withelectron configurationproblems, go toSupplemental Practice

Problems in Appendix A.

Practice!

Strontium-containing compoundsare used to produce the brightred seen in these road flares.

162

ReteachVisual-Spatial Have studentgroups make four flashcards.

Each card should identify anelement by its period number,group number, valence electrons,and family name, respectively.Student groups should challengeone another to identify theelements.

Skill A student is givenclues about three elements. One ofthe elements is an alkali metal, one is from the carbon family, and one is from the nitrogen family. • Element A is metallic, shiny, a

good conductor, and reacts slowlywith HCl to form H2 gas.

• Element B is a yellow solid and isnot a good conductor.

• Element C exhibits a metallicluster, conducts electricity, andforms a white powder whenexposed to air.

Have students propose identitiesfor each element, support theirchoices, and write electron config-urations for each.

A: Most likely lithium becauseit is an alkali metal that, in itsgroup, reacts the slowest withHCl. [He]2s1

B: Must be sulfur because of itsyellow color, nonconductive prop-erties, and the fact that it is in thesame group as oxygen. [Ne]3s23p4

C: Must be lead because it’sgray, malleable, and in the samegroup as carbon.[Xe]6s24f145d106p2

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PROBLEMS7. Electron

configuration Group Period Blocka. [Ne]3s2 2A 3 s-blockb. [He]2s2 2A 2 s-blockc. [Kr]5s24d105p5 7B 5 p-block8. See the Solutions Manual.9. a. Sc, Y, La, Ac

b. N, P, As, Sb, Bic. Ne, Ar, Kr, Xe, Rn


10. Chemical behavior is determined bythe number of valence electrons.Elements in the same group have thesame valence electron configurations.

11. a. p-block; b. s-block; c. d-block; d. p-block

12. a. They are the same number.b. They are the same number.

13. group 6A, period 3; p-block14. It is most likely a nonmetal noble gas

located on the extreme right side ofthe periodic table. Other gases arereactive.

15. Sketches should look similar to Figure 6-10. See the Solutions Manual for a sample sketch.

163

1 Focus


2 TeachConcept DevelopmentHelp students develop the conceptof periodic trends by providingthem with opportunities to plotspecific data and analyze theresulting graphs.

Figure Caption QuestionFigure 6-11c What causes theincrease in radii as you move downa group? Electrons occupy larger,higher-energy orbitals; inner coreelectrons shield valence electronsfrom the increased charge in thenucleus.

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Pages 162–1634(D), 6(A), 6(C)

6.3Section

Focus Transparency

6.3 Periodic Trends 163

Objectives• Compare period and group

trends of several properties.

• Relate period and grouptrends in atomic radii toelectron configuration.

Vocabularyionionization energyoctet ruleelectronegativity

Section Periodic Trends

Many properties of the elements tend to change in a predictable way, knownas a trend, as you move across a period or down a group. You will exploreseveral periodic trends in this section. Do the miniLAB on the next page toexplore several properties that behave periodically.

Atomic RadiusThe electron cloud surrounding a nucleus is based on probability and doesnot have a clearly defined edge. It is true that the outer limit of an electroncloud is defined as the spherical surface within which there is a 90% proba-bility of finding an electron. However, this surface does not exist in a physi-cal way, as the outer surface of a golf ball does. Atomic size is defined byhow closely an atom lies to a neighboring atom. Because the nature of theneighboring atom can vary from one substance to another, the size of the atomitself also tends to vary somewhat from substance to substance.

For metals such as sodium, the atomic radius is defined as half the distancebetween adjacent nuclei in a crystal of the element. See Figure 6-11a. Forelements that commonly occur as molecules, such as many nonmetals, the

6.3

Radius

Bonded metallic sodium atoms ina crystal lattice

186 pm

372 pm

Bonded nonmetalhydrogen atoms

Radius

74 pm

37 pm

H 37 He 31

Li 152

Na 186

K 227

Rb 248

Cs 265

Be 112

Mg 160

Ca 197

Sr 215

Ba 222

B 85

Al 143

Ga 135

In 167

Tl 170

C 77

Si 118

Ge 122

Sn 140

Pb 146

N 75

P 110

As 120

Sb 140

Bi 150

O 73

S 103

Se 119

Te 142

Po 168

F 72

Cl 100

Br 114

I 133

At 140

Ne 71

Ar 98

Kr 112

Xe 131

Rn 140

1A

1

2

3

4

5

6

2A 3A 4A 5A 6A 7A

8AChemical symbolAtomic radius

Relative size

K 227

The atomic radii of the representative elements are given in picome-ters (1 � 10-12 meters) and their relative sizes are shown. The radiifor the transition metals have been omitted because they exhibitmany exceptions to the general trends shown here. What causes theincrease in radii as you move down a group?

cThe radius of a nonmetalatom is often determinedfrom a diatomic molecule ofan element.

b

The radius of a metal atom ina metallic crystal is one-halfthe distance between twoadjacent atoms in the crystal.

a

Figure 6-11

The table gives atomic radii ofthe representative elements.

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Section Focus Transparency 22 Inferring CharacteristicsUse with Chapter 6, Section 6.3



What clues does the arrangement of the football players

on the field give about the functions of their positions?

What characteristics does a football player have based on

the position played?

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Study Guide for Content Mastery,pp. 35–36


Lab Manual, pp. 41–44 Solving Problems: A Chemistry Handbook, Section 6.3 L2

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atomic radius is defined as half the distance between nuclei of identical atomsthat are chemically bonded together. The atomic radius of a nonmetal diatomichydrogen molecule (H2) is shown in Figure 6-11b.

Trends within periods A pattern in atomic size emerges as you look acrossa period in Figure 6-11c. In general, there is a decrease in atomic radii asyou move left-to-right across a period. This trend is caused by the increas-ing positive charge in the nucleus and the fact that the principal energy levelwithin a period remains the same. Each successive element has one additionalproton and electron, and each additional electron is added to the same prin-cipal energy level. Moving across a period, no additional electrons comebetween the valence electrons and the nucleus. Thus, the valence electronsare not shielded from the increased nuclear charge. The result is that theincreased nuclear charge pulls the outermost electrons closer to the nucleus.

Trends within groups Atomic radii generally increase as you move down agroup. The nuclear charge increases and electrons are added to successivelyhigher principal energy levels. Although you might think the increased nuclearcharge would pull the outer electrons toward the nucleus and make the atomsmaller, this effect is overpowered by several other factors. Moving down agroup, the outermost orbital increases in size along with the increasing princi-pal energy level; thus, making the atom larger. The larger orbital means that theouter electrons are farther from the nucleus. This increased distance offsets thegreater pull of the increased nuclear charge. Also, as additional orbitals betweenthe nucleus and the outer electrons are occupied, these electrons shield the outerelectrons from the pull of the nucleus. Figure 6-12 summarizes the group andperiod trends in atomic radii.


Periodicity of Molar Heats ofFusion and VaporizationMaking and Using Graphs The heats requiredto melt or to vaporize a mole (a specific amountof matter) of matter are known as the molarheat of fusion (Hf) and the molar heat of vapor-ization (Hv), respectively. These heats are uniqueproperties of each element. You will investigateif the molar heats of fusion and vaporization forthe period 2 and 3 elements behave in a periodicfashion.

Materials either a graphing calculator, a computer graphing program, or graph paper;Appendix Table C-6 or access to comparable element data references

ProcedureUse Table C-6 in Appendix C to look up andrecord the molar heat of fusion and the molarheat of vaporization for the period 3 elementslisted in the table. Then, record the same datafor the period 2 elements.

Analysis1. Graph molar heats of fusion versus atomic

number. Connect the points with straightlines and label the curve. Do the same formolar heats of vaporization.

2. Do the graphs repeat in a periodic fashion?Describe the graphs to support your answer.

miniLAB

Figure 6-12

This small table provides a sum-mary of the general trends inatomic radii.

Trends in Atomic Radii

Generally decreases

Gen

eral

ly in

crea

ses

Molar Heat Data

Element Atomic number Hf (kJ/mol) Hv (kJ/mol)

Na 11

Mg 12

Al 13

Si 14

P 15

S 16

Cl 17

Ar 18

164

Purpose Students will use graphs to deter-mine if molar heats of fusion andvaporization behave in a periodicway.

Process SkillsComparing and contrasting, makingand using graphs, sequencing,thinking critically, using numbers

Teaching Strategies• Students can use sources other

than Appendix Tables C-6 and C-13 to find molar heats of fusionand vaporization. The Internet isalso a good source for periodictable information.

• If students use TI graphing calcu-lators, remind them to reset the xand y values in the WINDOW ofthe calculator so that all of thedata can be seen.

Expected Results

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Analysis1. See sample graph in the Solutions

Manual. Graphs should reflect datashown in data table.

2. Yes, both molar heat of fusion andvaporization repeat in a periodic fashion,and, therefore, are periodic properties of elements.

Performance Have students graphother properties, such as density or specificheat, to see if they behave in a periodic way.Use the Performance Task Assessment List forGraph from Data in PASC, p. 39. L2

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Molar Heat Data

Element Atomic Hf Hvnumber (kJ/mol) (kJ/mol)

Li 3 3 148

Be 4 7.9 298

B 5 50.2 504

C 6 104.6 711

N 7 0.072 5.58

O 8 0.44 6.82

F 9 0.51 6.54

Ne 10 0.34 1.77

Na 11 2.06 97.4

Mg 12 8.5 127

Al 13 10.7 291

Si 14 50.2 359

P 15 0.659 362

S 16 1.73 9.62

Cl 17 6.41 20.4

Ar 18 1.18 6.52

Pages 164–1652(C), 2(D), 2(E), 4(D), 6(A), 6(C)


EXAMPLE PROBLEM 6-2Interpreting Trends in Atomic RadiiWhich has the largest atomic radius: carbon (C), fluorine (F), beryllium(Be), or lithium (Li)? Do not use Figure 6-11 to answer the question.Explain your answer in terms of trends in atomic radii.

1. Analyze the ProblemYou are given four elements. First, determine the groups and periodsthe elements occupy. Then apply the general trends in atomic radii todetermine which has the largest atomic radius.

2. Solve for the UnknownFrom the periodic table, all the elements are found to be in period 2.Ordering the elements from left-to-right across the period yields: Li, Be, C, FApplying the trend of decreasing radii across a period means thatlithium, the first element in period 2, has the largest radius.

3. Evaluating the AnswerThe group trend in atomic radii has been correctly applied. Checkingradii values from Figure 6-11 verifies the answer.

PRACTICE PROBLEMSAnswer the following questions using your knowledge of group andperiod trends in atomic radii. Do not use the atomic radii values inFigure 6-11 to answer the questions.

16. Which has the largest radius: magnesium (Mg), silicon (Si), sulfur (S),or sodium (Na)? The smallest?

17. Which has the largest radius: helium (He), xenon (Xe), or argon (Ar)?The smallest?

18. Can you determine which of two unknown elements has the largerradius if the only known information is that the atomic number ofone of the elements is 20 greater than the other?

For more practice with periodic trendproblems, go toSupplemental Practice

Problems in Appendix A.

Practice!

Ionic RadiusAtoms can gain or lose one or more electrons to form ions. Because electronsare negatively charged, atoms that gain or lose electrons acquire a net charge.Thus, an ion is an atom or a bonded group of atoms that has a positive ornegative charge. You’ll learn about ions in detail in Chapter 8, but for now,let’s look at how the formation of an ion affects the size of an atom.

When atoms lose electrons and form positively charged ions, they alwaysbecome smaller. For example, as shown in Figure 6-13a on the next page asodium atom with a radius of 186 pm shrinks to a radius of 95 pm when itforms a positive sodium ion. The reason for the decrease in size is twofold.The electron lost from the atom will always be a valence electron. The lossof a valence electron may leave a completely empty outer orbital, whichresults in a smaller radius. Furthermore, the electrostatic repulsion betweenthe now fewer number of remaining electrons decreases, allowing them to bepulled closer to the nucleus.

When atoms gain electrons and form negatively charged ions, they alwaysbecome larger, as shown in Figure 6-13b. The addition of an electron to an

165

PROBLEMSHave students refer to AppendixD for complete solutions toPractice Problems.16. largest: Na

smallest: S17. largest: Xe

smallest: He18. No. If all you know is that

the atomic number of oneelement is 20 greater thanthat of the other, then youwill be unable to deter-mine the specific groupsand periods that theelements are in. Withoutthis information, youcannot apply the periodictrends in atomic size todetermine which elementhas the larger radius.


Visual-Spatial Draw an atomic modelof sodium on the board. The atom

should have eleven protons in the nucleus,two electrons in the first shell, eight elec-trons in the second shell, and one electron inthe third shell. Ask students what happensto the size of the atom if the outermostvalence electron is removed. Have students

draw atomic models of other elementswithin the same group or period. Make surethey understand that as they move across aperiod, the increase in the nuclear chargehas a greater impact on the atomic radiithan the increasing number of electronsaround the nucleus. This results in the trendof decreasing atomic radii.

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Learning Disabled

Math in ChemistryMath in Chemistry

Visual-Spatial Studentsoften have difficulty inter-

preting graphs and generalizing theinformation.• Provide students with several

graphs and ask them to writeseveral sentences describing anytrends they see in the data. Thegraphs they analyze do not haveto be of periodic trends; select awide variety of graphs, such asbusiness trends, seasonal temper-ature, population over time, cropyields, and rainfall.

• Select a new scientific graph andask students specific questionsthat require them to read andanalyze data points on the graph.Ask them to summarize anytrends shown in the graph. Then,ask a question that requires themto apply the trends in order toanswer.

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atom increases the electrostatic repulsion between the atom’s outer electrons,forcing them to move farther apart. The increased distance between the outerelectrons results in a larger radius.

Trends within periods The ionic radii of most of the representative ele-ments are shown in Figure 6-14. Note that elements on the left side of thetable form smaller positive ions, and elements on the right side of the tableform larger negative ions. In general, as you move left-to-right across aperiod, the size of the positive ions gradually decreases. Then, beginning ingroup 5A or 6A, the size of the much larger negative ions also graduallydecreases.

Trends within groups As you move down a group, an ion’s outer electronsare in higher principal energy levels, resulting in a gradual increase in ionicsize. Thus, the ionic radii of both positive and negative ions increase as youmove down a group. Figure 6-15 on the next page summarizes the group andperiod trends in ionic radii.


Figure 6-13

Atoms undergo significantchanges in size when formingions. The sodium atom losesan electron and becomessmaller. The chlorine iongains an electron and becomeslarger. How is each ion’s electronconfiguration related to thoseof the noble gas elements?

b

a

186 pm 95 pm 181 pm100 pm

[Ne]3s1 Sodium atom (Na)

[Ne]Sodium ion (Na�) Chlorine atom (Cl)

[Ne]3s23p5Chlorine ion (Cl�)[Ne]3s23p6 or [Ar]

a b

Figure 6-14

The table shows the ionic radiiof most of the representativeelements. The ion sizes areshown relative to one another,while the actual radii are givenin picometers (1 � 10-12 meters).Note that the elements on theleft side of the table form posi-tive ions, and those on the rightform negative ions.

Li 76

Na 102

K 138

Rb 152

Cs 167

Be 31

Mg 72

Ca 100

Sr 118

Ba 135

B 20

Al 54

Ga 62

In 81

Tl 95

C 15

Si 41

Ge 53

Sn 71

Pb 84

N 146

P 212

As 222

Sb 62

Bi 74

O 140

S 184

Se 198

Te 221

F 133

Cl 181

Br 195

I 220

K 138

1�

1A

Chemical symbol

Charge

Ionic radius

Relative size

2

3

4

5

6

1�

1�

1�

1�

1�

2A

Peri

od

3A 4A 5A 6A 7A

2�

2�

2�

2�

2 �

3�

3�

3�

3�

3�

4�

4�

4�

4�

4�

3�

3�

3�

5�

5�

2�

2�

2�

2�

1�

1�

1�

1�

166

Figure Caption QuestionsFigure 6-13 How is each ion’selectron configuration related tothose of the noble gas elements?Ions have the same electronconfiguration as the nearestnoble gas in the periodic table.Figure 6-16 What trend in firstionization energies do you observeas you move down a group?Ionization energies generallydecrease down a group.

Performance Askstudents to draw a metal atom andits ion, showing relative sizes. Theion will be smaller. Ask students torepeat the procedure with a halogenatom and its ion. The ion will belarger. Use the Performance TaskAssessment List for ScientificDrawing in PASC, p. 55.

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Activity of Alkali Metals

Purpose To demonstrate that chemical reactivityfollows a predictable pattern

MaterialsOverhead projector; explosion shield; 600-mL beakers (3); phenolphthalein indi-

cator (10 drops); clear plastic wrap; cubesof Li, Na, and K, (∼ 2 mm on a side); wirescreen (10 cm � 10 cm) See page 150C for preparation of solutions.

Safety Precautions

Wear safety goggles and an apron. Use anexplosion shield. Make sure there are noopen flames or possible ignition sources.

Disposal Neutralize the solutions formedusing acetic acid or dilute HCl. Flush theneutralized solutions down the drain withcopious amounts of water.

ProcedureCover the stage and lower lens of an over-head projector with clear plastic wrap. Placea 600-mL beaker containing 100 mL ofwater on the projector. CAUTION: Place

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Demonstration

Pages 166–1676(A), 6(C)


Teaching Transparencies 20, 21 and Masters

Lab Manual, pp. 45–48 L2

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Ionization EnergyTo form a positive ion, an electron must be removed from a neutral atom. Thisrequires energy. The energy is needed to overcome the attraction between thepositive charge in the nucleus and the negative charge of the electron.Ionization energy is defined as the energy required to remove an electronfrom a gaseous atom. For example, 8.64 � 10-19 J is required to remove anelectron from a gaseous lithium atom. The energy required to remove the firstelectron from an atom is called the first ionization energy. Therefore, the firstionization energy of lithium equals 8.64 � 10-19 J. The loss of the electronresults in the formation of a Li+ ion. The first ionization energies of the ele-ments in periods 1 through 5 are plotted on the graph in Figure 6-16.

Think of ionization energy as an indication of how strongly an atom’snucleus holds onto its valence electrons. A high ionization energy value indi-cates the atom has a strong hold on its electrons. Atoms with large ionizationenergy values are less likely to form positive ions. Likewise, a low ioniza-tion energy value indicates an atom loses its outer electron easily. Such atomsare likely to form positive ions.

Take a close look at the graph in Figure 6-16. Each set of connected pointsrepresents the elements in a period. From the graph, it is clear that the group1A metals have low ionization energies. Thus, group 1A metals (Li, Na K,Rb) are likely to form positive ions. It also is clear that the group 8A elements(He, Ne, Ar, Kr, Xe) have high ionization energies and are unlikely to formions. Gases of group 8A are extremely unreactive—their stable electron con-figuration greatly limits their reactivity.

After removing the first electron from an atom, it is possible to removeadditional electrons. The amount of energy required to remove a second elec-tron from a 1+ ion is called the second ionization energy, the amount ofenergy required to remove a third electron from a 2+ ion is called the thirdionization energy, and so on. Table 6-2 on the next page lists the first throughninth ionization energies for elements in period 2.

Reading across Table 6-2 from left-to-right, you see that the energyrequired for each successive ionization always increases. However, theincrease in energy does not occursmoothly. Note that for each elementthere is an ionization for which therequired energy jumps dramatically.For example, the second ionizationenergy of lithium (7300 kJ/mol) ismuch greater than its first ionizationenergy (520 kJ/mol). This means alithium atom is relatively likely to loseits first valence electron, but extremelyunlikely to lose its second.

If you examine the table, you’ll seethat the ionization at which the largejump in energy occurs is related to theatom’s number of valence electrons.Lithium has one valence electron andthe jump occurs after the first ionizationenergy. Lithium easily forms the com-mon lithium 1+ ion, but is unlikely toform a lithium 2+ ion. The jump in ion-ization energy shows that atoms hold


Trends in Ionic Radii

Positive ions decrease

Negativeions

decrease

Gen

eral

ly in

crea

ses

Figure 6-15

This small table provides a summary of the general trendsin ionic radii.

K Rb

0 10

Period 2 Period 3 Period 4 Period 5

20 30 50 6040

Firs

t io

niz

atio

n e

ner

gy

(kJ/

mo

l)

2500

2000

1500

1000

500

0

Atomic number

First Ionization Energy of Elements in Periods 1–5

H

He

Li

Ne

Ar

Na

XeKr

Figure 6-16

The graph shows the first ioniza-tion energies for elements inperiods 1 through 5. Note thehigh energies required toremove an electron from anoble gas element. What trendin first ionization energies doyou observe as you move downa group?

an explosion shield around the projector.Turn on the projector and darken the room.Drop a small piece of lithium into the water.CAUTION: Quickly cover the beaker witha wire screen. The gas produced is flam-mable. In separate beakers, repeat the proce-dure using Na and K.

ResultsMetals skim across the water with speedsrelated to their activity. Li: slow, least

active; Na: fast, active; K: flammable, veryactive.

Analysis1. Which metal reacts the fastest? K2. How does the element’s position in the

column on the periodic table relate toits reactivity? Li is first and least reac-tive; K is third and most reactive.

3. Which metal has its outer-level electronfarthest from the nucleus? K

Knowledge Have students applythe trend in reactivities they observed topredict how the activity of Rb and Cs willcompare with that of Li, Na, and K. Rband Cs will be more reactive, with Csbeing the most reactive. L2

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Math in ChemistryMath in Chemistry

Logical-Mathematical Assign

a trend to each group ofstudents and have them create atable of data for that trend for thefirst 40 elements of the periodictable. Assigned trends shouldinclude ionization energy, electronaffinity, electronegativity, atomicradii, ionic radii, density, andmelting point. Students may need a variety of resources, such as the text, a CRC Handbook ofChemistry and Physics, a periodictable, Internet sites, or other refer-ence materials, to complete theirdata table.

Have students enter the data as a set of lists into a graphing calcu-lator. The first list should be theatomic numbers 1 through 40.These data should be graphed onthe x-axis. The specific data relatedto the trend should be graphed onthe y-axis. Have students displayand print the graph. On the printedgraph, have them draw a verticalline through each alkali metal(explain that the interval betweeneach vertical line represents aperiod). They should then select acolor and color-code each datapoint that represents an alkalimetal. A different color should beused to color-code each noble gas.Repeat this process with a thirdcolor for the halogens. Finally,have students write a paragraphdescribing the trend that resultswhen comparing elements within aperiod and elements in the samegroup.

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onto their inner core electrons much more strongly than they hold onto theirvalence electrons. Where does the jump in ionization energy occur for oxy-gen, an atom with six valence electrons?

Trends within periods As shown in Figure 6-16 and by the values in Table6-2, first ionization energies generally increase as you move left-to-rightacross a period. The increased nuclear charge of each successive element pro-duces an increased hold on the valence electrons.

Trends within groups First ionization energies generally decrease as youmove down a group. This decrease in energy occurs because atomic sizeincreases as you move down the group. With the valence electrons fartherfrom the nucleus, less energy is required to remove them. Figure 6-17 sum-marizes the group and period trends in first ionization energies.

Octet rule When a sodium atom loses its single valence electron to form a1+ sodium ion, its electron configuration changes as shown below.

Sodium atom 1s22s22p63s1 Sodium ion 1s22s22p6

Note that the sodium ion has the same electron configuration as neon(1s22s22p6), a noble gas. This observation leads to one of the most importantprinciples in chemistry, the octet rule. The octet rule states that atoms tendto gain, lose, or share electrons in order to acquire a full set of eight valenceelectrons. This reinforces what you learned earlier that the electron configu-ration of filled s and p orbitals of the same energy level (consisting of eightvalence electrons) is unusually stable. Note that the first period elements arean exception to the rule, as they are complete with only two valence electrons.

The octet rule is useful for determining the type of ions likely to form.Elements on the right side of the periodic table tend to gain electrons in orderto acquire the noble gas configuration; therefore, these elements tend to formnegative ions. In a similar manner, elements on the left side of the table tendto lose electrons and form positive ions.

ElectronegativityThe electronegativity of an element indicates the relative ability of itsatoms to attract electrons in a chemical bond. Figure 6-18 lists the elec-tronegativity values for most of the elements. These values are calculatedbased upon a number of factors, and are expressed in terms of a numerical


Successive Ionization Energies for the Period 2 Elements

ElementValence Ionization energy (kJ/mol)*

electrons 1st 2nd 3rd 4th 5th 6th 7th 8th 9th

Li 1 520 7300

Be 2 900 1760 14 850

B 3 800 2430 3660 25 020

C 4 1090 2350 4620 6220 37 830

N 5 1400 2860 4580 7480 9440 53 270

O 6 1310 3390 5300 7470 10 980 13 330 71 330

F 7 1680 3370 6050 8410 11 020 15 160 17 870 92 040

Ne 8 2080 3950 6120 9370 12 180 15 240 20 000 23 070 115 380

* mol is an abbreviation for mole, a quantity of matter.

Table 6-2

Figure 6-17

This small table provides a sum-mary of the general trends infirst ionization energies.

Generally increases

Trends in First Ionizationi

Gen

eral

ly d

ecre

ases

168

Visual LearningTable 6-2 Have students study thetable for the period 2 elements. Askthem to predict how they could usethe chart of ionization energies topredict the number of electrons an atom would lose when formingan ion. L2

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Pages 168–1696(A), 6(C)

Quick Demo

Ask students topredict which element, magne-sium or calcium, will be morereactive. Drop a small piece ofmagnesium into several milli-liters of water in a test tube.Have students record theirobservations. Repeat this proce-dure with a small piece ofcalcium metal in a second testtube. Make sure to use a freshpiece of calcium that has notstarted to oxidize. Afterstudents record their observa-tions, add several drops ofphenolphthalein to both testtubes and discuss what thecolor change indicates.

Students should notice thatcalcium is noticeably more reac-tive than the magnesium. Aslow reaction between themagnesium and the water doesoccur, as evidenced by the smallbubbles and slight colorchange. Repeat the reactionwith hot water, and studentsshould note that the reactionoccurs more vigorously for bothmetals. Neutralize the solutionscreated and flush them downthe drain with water.

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Group Numbering SystemsIntrapersonal Have students investi-gate and report on different num-

bering systems used on periodic tables.Have students summarize their findingsand place them in their journals.

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CD-ROMChemistry: Matter and ChangeAnimation: Electronegativity

value of 3.98 or less. The units of electronegativity are arbitrary units calledPaulings, named after American scientist Linus Pauling (1901–1994).

Note that because the noble gases form very few compounds, they havebeen left out of Figure 6-18. Fluorine is the most electronegative element,with a value of 3.98, and cesium and francium are the least electronegativeelements, with values of 0.79 and 0.7, respectively. In a chemical bond, theatom with the greater electronegativity more strongly attracts the bond’s elec-trons. You will use electronegativity values in upcoming chapters to helpdetermine the types of bonds that exist between elements in a compound.

Trends within periods and groups Electronegativity generally decreasesas you move down a group, and increases as you move left-to-right acrossa period; therefore, the lowest electronegativities are found at the lower leftside of the periodic table, while the highest electronegativities are found atthe upper right.


1H

2.20

2He

3Li

0.9811Na

0.9319K

0.8237Rb

0.8255Cs

0.79

4Be

1.5712Mg1.3120Ca

1.0038Sr

0.9556Ba

0.8987Fr

0.70

88Ra

0.90

5B

2.0413Al

1.6131Ga

1.8149In

1.7881Tl

1.8

6C

2.5514Si

1.9032Ge

2.0150Sn

1.9682Pb1.8

7N

3.0415P

2.1933As

2.1851Sb

2.0583Bi1.9

8O

3.4416S

2.5834Se

2.5552Te2.184Po2.0

9F

3.9817Cl

3.1635Br

2.9653I

2.6685At2.2

10Ne

18Ar

36Kr

54Xe

86Rn

21Sc

1.3639Y

1.2257La1.189Ac1.1

22Ti

1.5440Zr

1.3372Hf1.3104Rf

23V

1.6341Nb1.673Ta1.5105Db

24Cr

1.6642Mo2.1674W1.7106Sg

25Mn1.5543Tc

2.1075Re1.9107Bh

26Fe

1.8344Ru2.276Os2.2108Hs

27Co

1.8845Rh

2.2877Ir

2.2109Mt

110Uun

28Ni

1.9146Pd

2.2078Pt2.2

111Uuu

29Cu

1.9047Ag

1.9379Au2.4

112Uub

30Zn

1.6548Cd

1.6980Hg1.9

electronegativity � 1.0

1.0 � electronegativity � 2.0



Electronegativity Values in Paulings

Dec

reas

ing

ele

ctro

neg

ativ

ity

Increasing electronegativity


19. Sketch a simplified periodic table and use arrowsand labels to compare period and group trends inatomic and ionic radii, ionization energies, andelectronegativities.

20. Explain how the period and group trends in atomicradii are related to electron configuration.

21. Which has the largest atomic radius: nitrogen (N),antimony (Sb), or arsenic (As)? The smallest?

22. For each of the following properties, indicatewhether fluorine or bromine has a larger value.a. electronegativity c. atomic radiusb. ionic radius d. ionization energy

23. Thinking Critically Explain why it takes moreenergy to remove the second electron from alithium atom than it does to remove the fourthelectron from a carbon atom.

24. Making and Using Graphs Graph the atomicradii of the group A elements in periods 2, 3, and4 versus their atomic numbers. Connect the pointsof elements in each period, so that there are three

separate curves on the graph. Summarize thetrends in atomic radii shown on your graph.Explain.

Figure 6-18

The table shows the electroneg-ativity values for most of theelements. In which areas of theperiodic table do the highestelectronegativities tend tooccur? The lowest?

Figure Caption QuestionsFigure 6-18 In which areas of theperiodic table do the highest elec-tronegativities tend to occur? topright The lowest? bottom left

3 AssessCheck for UnderstandingInformally quiz students on periodictrends by giving them pairs ofelements and asking them to identifywhich is larger, smaller, more reac-tive, or more electronegative.

ReteachVisual-Spatial Havestudents label the trends on an

outline of a periodic table by usingarrows pointing in the directionthat the trend increases. Repeat thislabeling process with the othertrends studied.

Skill Given the followingletters representing elements ingroups (CNJ, ADG, EOSU, BZ,DT, FH, KV, IM), have studentsplace them in the correct place on a blank periodic table.

A: a gas, no assigned electroneg-ativity; B: a halogen; E: 1 proton; O,S, and U: alkali metals; U: largestatomic size in its group; S: smallestatomic size in its group; B: greateratomic mass than Z; A: 2 protons;D: 8 more electrons than G; J:smaller atomic radii than N; D andT: 3 valence electrons; D: lowerionization energy than T; K: has 6electrons; C: alkaline earth metalwith the highest ionization energy isits group; F: lower electronegativitythan B but higher than IPeriods 1–4: E A / S C T K M H Z G /O J D V I F B D / U N

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19. See the Solutions Manual for asample sketch.

20. Atomic radii increase down a groupas electrons are added to higherenergy levels and inner core elec-trons shield the valence electronsfrom the increased nuclear charge.Atomic radii decrease across a periodas increased nuclear charge coupled

with unchanging shielding by innercore electrons pulls the valence elec-trons (being added to the sameenergy level) closer to the nucleus.

21. antimony (Sb); nitrogen (N)22. a. fluorine c. bromine

b. bromine d. fluorine23. Lithium’s second removed electron is

an inner core electron, not a valence

electron. Carbon’s fourth removedelectron is still a valence electron.

24. See Solutions Manual. In general,atomic radii decrease across aperiod due to increased nuclearcharge and increase down a groupdue to shielding from increasednuclear charge.

169

Pre-Lab


Pre-Lab

1. Read the entire CHEMLAB.

2. Prepare a data table similar to the one below torecord the observations you make during the lab.

3. Examine the periodic table. What is the physicalstate of most metals? Nonmetals? Metalloids?

4. Look up the definitions of the terms luster, mal-leability, and electrical conductivity. To what ele-ments do they apply?

Safety Precautions• Wear safety goggles and a lab apron at all times.• Do not handle elements with bare hands.• 1.0M HCl is harmful to eyes and clothing.• Never test chemicals by tasting.• Follow any additional safety precautions provided by your teacher.

ProblemWhat is the pattern of prop-erties of the representativeelements?

Objectives• Observe properties of vari-

ous elements.• Classify elements as metals,

nonmetals, and metalloids.• Examine general trends

within the periodic table.

Materialsstoppered test

tubes containingsmall samples ofelements

plastic dishes con-taining samplesof elements

conductivity apparatus

1.0M HCltest tubes (6)test tube rack10-mL graduated

cylinderspatulasmall hammerglass marking

pencil

Descriptive Chemistry of theElementsWhat do elements look like? How do they behave? Can periodic

trends in the properties of elements be observed? You cannotexamine all of the elements on the periodic table because of limitedavailability, cost, and safety concerns. However, you can observe sev-eral of the representative elements, classify them, and compare theirproperties. The observation of the properties of elements is calleddescriptive chemistry.

CHEMLAB 6

Observation of Elements

Appearance and Malleable Reactivity ElectricalElementphysical state or brittle? with HCl conductivity

Classification

170

6CHEMLAB

Preparation Time AllotmentOne and a half laboratory periods

Process SkillsObserving and inferring, interpretingdata, classifying, comparing andcontrasting

Safety PrecautionsStudents must wear aprons andgoggles because the elements couldshatter when struck with thehammer. Also caution studentsabout the risk of hydrochloric acidto eyes and clothes. Remindstudents that they should never tastea chemical substance.

DisposalThe HCl solution may be flusheddown the drain with a large amountof water.

Preparation of Materials• The following element samples

should be obtained for use in thislab. Test tubes samples: carbon,nitrogen, oxygen, magnesium,aluminum, silicon, red phos-phorus, sulfur, chlorine, calcium,selenium, tin, iodine, and lead.

• Dish samples: carbon, magnesium,aluminum, silicon, sulfur, and tin

• The lab can be performed even ifsome of the listed elements arenot available.

• If other elements are substituted,make sure they do not producehazardous reactions.

• See page 150C for preparation ofall solutions.

3. All naturally occurring metalsare solids, except for mercury,which is a liquid at roomtemperature. All metalloidsare solids. Nonmetals areprimarily gases and solids, withbromine being the only liquid.

4. Luster: shininess; malleability:capable of being flattenedinto sheets or formed intoshapes; electrical conductivity:capable of transmitting anelectric current; They are prop-erties commonly associatedwith metals.

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Observation of Elements Element Appearance Malleable Reactivity Electrical Classification

and physical state or brittle? with HCI conductivity

carbon gray/black, dull solid brittle no yes metalloid

oxygen colorless gas ---- ---- ---- nonmetal

magnesium shiny, silver solid malleable yes yes metal

silicon shiny, gray solid brittle no yes metalloid

sulfur dull, yellow solid brittle no yes nonmetal

chlorine yellow-green gas not tested not tested not tested nonmetal

171

CHEMLAB 171

Procedure

1. Observe and record the appearance of the elementsample in each test tube. Observations shouldinclude physical state, color, and other characteris-tics such as luster and texture. CAUTION: Do notremove the stoppers from the test tubes.

2. Remove a small sample of each of the elementscontained in a dish and place it on a hard surfacedesignated by your teacher. Gently tap each elementsample with a small hammer. CAUTION: Safetygoggles must be worn. If the element is malleable itwill flatten. If it is brittle, it will shatter. Recordyour observations.

3. Use the conductivity tester to determine which ele-ments conduct electricity. An illuminated light bulbis evidence of electrical conductivity. Record yourresults in your data table. Clean the electrodes withwater and make sure they are dry before testingeach element.

4. Label each test tube with the symbol for one of theelements in the plastic dishes. Using a graduatedcylinder, add 5 mL of water to each test tube.

5. Use a spatula to put a small amount of each of thesix elements (approximately 0.2 g or a 1-cm longribbon) into the test tube labeled with its chemicalsymbol. Using a graduated cylinder, add 5 mL of1.0M HCl to each test tube. Observe each test tubefor at least one minute. The formation of bubbles isevidence of a reaction between the acid and theelement. Record your observations.

Cleanup and Disposal

Dispose of all materials as instructed by your teacher.

Analyze and Conclude

1. Interpreting Data Metals are usually malleableand good conductors of electricity. They are gener-ally lustrous and silver or white in color. Manyreact with acids. Write the word “metal” beneaththe Classification heading in the data table forthose element samples that display the generalcharacteristics of metals.

2. Interpreting Data Nonmetals can be solids, liq-uids, or gases. They do not conduct electricity anddo not react with acids. If a nonmetal is a solid, itis likely to be brittle and have color (other thanwhite or silver). Write the word “nonmetal”beneath the Classification heading in the data tablefor those element samples that display the generalcharacteristics of nonmetals.

3. Interpreting Data Metalloids combine some ofthe properties of both metals and nonmetals. Writethe word “metalloid” beneath the Classificationheading in the data table for those element samplesthat display the general characteristics of metalloids.

4. Making a Model Construct a periodic table andlabel the representative elements by group (1Athrough 7A). Using the information in your datatable and the periodic table, record the identities ofelements observed during the lab in your periodictable.

5. Interpreting Describe any trends among the ele-ments you observed in the lab.

Real-World Chemistry

1. Why did it take so long to discover the first noblegas element?

2. Research one of the most recently discovered ele-ments. New elements are created in particle acceler-ators and tend to be very unstable. Because of this,many of the properties of a new element can not bedetermined. Using periodic group trends in meltingand boiling point, predict whether the new elementyou selected is likely to be a solid, liquid, or gas.

CHAPTER 6 CHEMLAB

Procedure• Set up stations at various loca-

tions in the lab.

Expected ResultsSee data tables.

Analyze and Conclude1.–3. See completed Observation

of Elements table.4. See periodic table below.5. Students may note that the

metallic characteristic increasesfrom right-to-left, and fromtop-to-bottom.

Real-World Chemistry1. Many elements were discov-

ered by using electricity tobreak down compounds intotheir component elements.Because noble gases formvirtually no compounds, theelectrical decomposition tech-nique could not be used.

2. Answers will vary. Forexample, 114 may be a solidwith high melting point.

Skill Give each student ablank periodic table. Ask them todraw an arrow on their tablesshowing the direction of increasingmetallic properties across the tableand another showing increasingmetallic properties within a group.

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Pages 170–1711(A), 2(A), 2(B), 2(D), 2(E), 4(A),4(C), 4(D)

1A 2A 3A 4A 5A 6A 7A

2 6, C, 7, N, 8, O,metalloid nonmetal nonmetal

3 12, Mg, 13, Al, 14, Si, 15, P, 16, S, 17, Cl,metal metal metalloid nonmetal nonmetal nonmetal

4 20, Ca, 33, As, 34, Se,metal uncertain uncertain

5 50, Sn, 53, Imetal uncertain

6 82, Pb,metal


ChemLab and MiniLab Worksheets, pp. 22–24 L2

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172

last phosphors are scanned, a completeimage could not be formed. However, it isalso important that the phosphors do notglow for too long, as this would notallow for new images to form quickly.

Purpose Students will learn how electronbeams and phosphors are used tocreate images on television screens.

BackgroundIn electroluminescence, solid materials called phosphors emit light when exposed to radiation.Phosphors generally consist oflanthanide series elements. Forexample, a small amount ofeuropium oxide added to yttriumoxide results in a bright red phos-phor. Hundreds of thousands oftypes of phosphors have now been synthesized. Phosphors arecommonly used in computer andradar screens and fluorescentlamps.

Visual LearningPhosphors are arranged in clustersof dots called pixels. Turn on atelevision. Allow students to hold ahand lens up to the screen to lookfor the individual pixels. Theyshould stand about an arm’s lengthaway from the screen.

Teaching StrategiesAsk students to think about howthe speed at which the electronbeams scan the screen affects theclarity of the pictures. Havestudents research and summarizethe technology of high definitiontelevision.

Thinking Critically1. The phosphors used in a televi-

sion screen are stimulated toglow when they are hit with abeam of electrons. Thesebeams are created only whenthe television is turned on andis receiving an electronicsignal.

2. The phosphors must glow longenough for an entire pictureto form. If the first phosphorsscanned by the beam nolonger glow by the time the

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How It Works

1. Relating Cause and Effect Why don’t thephosphors in a television screen glow whenthe television is turned off?

2. Inferring Why is the length of time overwhich a phosphor emits light an importantfactor to consider when designing a televi-sion screen?

Television ScreenMost television screens are part of a cathode ray tube.As you know, a cathode ray tube is an evacuatedchamber which produces a beam of electrons, knownas a cathode ray. Electronic circuitry inside the televi-sion processes an electronic signal received from thetelevision station. The processed signal is used to varythe strength of several electron beams, while magneticfields are used to direct the beams to different parts ofthe screen.

How It Works


Cathodes

Anodes

Horizontal and verticaldeflecting electromagnets

Coating ofphosphor strips

Glass screen

Mask

Electron beams

1 The television receives an electronic signal from a television station by way of an antenna or cable.

2 Electronic circuits process and amplify the signal.

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Electron beams are directed at the screen end of the cathode ray tube.

4

4

Phosphors in the screen glow in red, green, and blue.Combinations of the phosphor colors form the screen image.

4

Pages 172–1733(C)

Study Guide 173

CHAPTER STUDY GUIDE6

Summary6.1 Development of the Modern Periodic Table• Periodic law states that when the elements are

arranged by increasing atomic number, there is aperiodic repetition of their chemical and physicalproperties.

• Newlands’s law of octaves, which was neveraccepted by fellow scientists, organized the ele-ments by increasing atomic mass. Mendeleev’s peri-odic table, which also organized elements byincreasing atomic mass, became the first widelyaccepted organization scheme for the elements.Moseley fixed the errors inherent in Mendeleev’stable by organizing the elements by increasingatomic number.

• The periodic table organizes the elements into peri-ods (rows) and groups (columns) by increasingatomic number. Elements with similar properties arein the same group.

• Elements are classified as either metals, nonmetals,or metalloids. The stair-step line on the table sepa-rates metals from nonmetals. Metalloids border thestair-step line.

6.2 Classification of the Elements• Elements in the same group on the periodic table

have similar chemical properties because they havethe same valence electron configuration.

• The four blocks of the periodic table can be charac-terized as follows:

s-block: filled or partially filled s orbitals.p-block: filled or partially filled p orbitals.d-block: filled outermost s orbital of energy level n,

and filled or partially filled d orbitals of energylevel n – 1.

f-block: filled outermost s orbital, and filled or par-tially filled 4f and 5f orbitals.

• For the group A elements, an atom’s group numberequals its number of valence electrons.

• The energy level of an atom’s valence electronsequals its period number.

• The s2p6 electron configuration of the group 8A ele-ments (noble gases) is exceptionally stable.

6.3 Periodic Trends• Atomic radii generally decrease as you move left-

to-right across a period, and increase as you movedown a group.

• Positive ions are smaller than the neutral atomsfrom which they form. Negative ions are larger thanthe neutral atoms from which they form.

• Ionic radii of both positive and negative ionsdecrease as you move left-to-right across a period.Ionic radii of both positive and negative ionsincrease as you move down a group.

• Ionization energy indicates how strongly an atomholds onto its electrons. After the valence electronshave been removed from an atom, there is a tremen-dous jump in the ionization energy required toremove the next electron.

• Ionization energies generally increase as you moveleft-to-right across a period, and decrease as youmove down a group.

• The octet rule states that atoms gain, lose, or shareelectrons in order to acquire the stable electron con-figuration of a noble gas.

• Electronegativity, which indicates the ability ofatoms of an element to attract electrons in a chemi-cal bond, plays a role in determining the type ofbond formed between elements in a compound.

• Electronegativity values range from 0.7 to 3.96, andgenerally increase as you move left-to-right across aperiod, and decrease as you move down a group.

Vocabulary• alkali metal (p. 155)• alkaline earth metal (p. 155)• electronegativity (p. 168)• group (p. 154)• halogen (p. 158)• inner transition metal (p. 158)

• ion (p. 165)• ionization energy (p. 167)• metal (p. 155)• metalloid (p. 158)• noble gas (p. 158)• nonmetal (p. 158)

• octet rule (p. 168)• period (p. 154)• periodic law (p. 153)• representative element (p. 154)• transition element (p. 154)• transition metal (p. 158)

Using the Vocabulary To reinforce chapter vocabulary,have students write a sentenceusing each term.

Review Strategies• Have students work in coopera-

tive groups to create a puzzle ofscrambled words using the vocab-ulary from Chapter 6. Whencomplete, the puzzle should behanded to another group to solve.The group completing the puzzlewill unscramble the words andprovide a definition.

• Have students label a blank peri-odic table with as many of thetrends as they have studied.

• Problems from Appendix A or theSupplemental Problems bookletcan be used for review. L2

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CHAPTERSTUDY GUIDE 6

Reviewing Chemistry is a compo-nent of the Teacher ClassroomResources package that wasprepared by The PrincetonReview. Use the Chapter 6review materials in this book to review the chapter with yourstudents.

PortfolioPortfolio

Review the portfolio options that are pro-vided throughout the chapter. Encouragestudents to select one product that demon-strates their best work for the chapter. Havestudents explain what they learned and why

they chose this example for placement intotheir portfolios. Additional portfolio optionsmay be found in the Challenge Problemsbooklet of the Teacher Classroom Resources.

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Portfolio Options

VIDEOTAPE/DVDMindJoggerVideoquizzesChapter 6: The Periodic Table

and Periodic LawHave students work in groups as they play the videoquiz gameto review key chapter concepts.


Go to the Chemistry Web site at science.glencoe.com or use the Chemistry CD-ROM for additional Chapter 6 Assessment.

Concept Mapping25.Complete the concept map using the following terms:

electronegativity, electron configuration, periodic trends,ionic radius, atomic radius, ionization energy, and peri-odic table.

Mastering Concepts26. Explain how Mendeleev’s periodic table was in error.

How was this error fixed? (6.1)

27. Explain the contribution of Newlands’s law of octavesto the development of the modern periodic table. (6.1)

28. German chemist Lothar Meyer and Russian chemistDmitri Mendeleev both proposed similar periodictables in 1869. Why is Mendeleev generally givencredit for the periodic table? (6.1)

29. How was Mendeleev’s periodic table organized? (6.1)

30. What is the periodic law? (6.1)

31. Identify each of the following as a metal, nonmetal, or metalloid. (6.1)

a. oxygen d. ironb. barium e. neonc. germanium f. praseodymium

32. Describe the general characteristics of metals. (6.1)

33. Match each numbered item on the right with the let-tered item that it is related to on the left. (6.1)

a. alkali metals 1. group 8Ab. halogens 2. group 1Ac. alkaline earth metals 3. group 2Ad. noble gases 4. group 7A

34. Identify each of the elements in problem 31 as a repre-sentative element or a transition element. (6.1)

35. Sketch a simplified periodic table and use labels toidentify the alkali metals, alkaline earth metals, transi-tion metals, inner transition metals, noble gases, andhalogens. (6.1)

36. A shiny solid element also is ductile. What side of theperiodic table is it likely to be found? (6.1)

37. What are the general properties of a metalloid? Listthree metalloid elements. (6.1)

38. What is the purpose of the heavy stair-step line on theperiodic table? (6.1)

39. Describe the two types of numbering used to identifygroups on the periodic table. (6.1)

40. Give the chemical symbol of each of the followingelements. (6.1)

a. the two elements that are liquids at room temperature

b. the noble gas with the greatest atomic massc. any metal from group 4Ad. any inner transition metal

41. Why do the elements chlorine and iodine have similarchemical properties? (6.2)

42. How are the numbers of valence electrons of the groupA elements related to the group number? (6.2)

43. How is the energy level of an atom’s valence electronsrelated to the period it is in on the periodic table? (6.2)

44. How many valence electrons do each of the noblegases have? (6.2)

45. What are the four blocks of the periodic table? (6.2)

46. In general, what electron configuration has the greateststability? (6.2)

47. Determine the group, period, and block in which eachof the following elements is located on the periodictable. (6.2)

a. [Kr]5s24d1 c. [He]2s22p6

b. [Ar]4s23d104p3 d. [Ne]3s23p1

48. Categorize each of the elements in problem 47 as arepresentative element or a transition metal. (6.2)

49. Explain how an atom’s valence electron configurationdetermines its place on the periodic table. (6.2)

50. Write the electron configuration for the element fittingeach of the following descriptions. (6.2)

a. the metal in group 5Ab. the halogen in period 3c. the alkali metal in period 2d. the transition metal that is a liquid at room

temperature

CHAPTER ASSESSMENT##CHAPTER ASSESSMENT6

1.

2.

3.

5. 6.4. 7.

174

Concept Mapping25. 1. periodic table;

2. electron configuration;3. periodic trends; 4.–7. electronegativity,ionic radius, atomic radius,ionization energy

Mastering Concepts26. Mendeleev used atomic

mass instead of atomicnumber to order theelements. This resulted insome elements being outof order. Moseley usedatomic number.

27. Newlands introduced theidea of periodicallyrepeating properties.

28. Mendeleev’s work waspublished first, he did moreto show periodic trends,and he predicted proper-ties of several yet-to-be-discovered elements.

29. The elements werearranged by increasingatomic mass into columnswith similar properties.

30. When the elements arearranged by increasingatomic number, there is aperiodic repetition of theirchemical and physicalproperties.

31. a. nonmetal d.metal b. metal e. nonmetalc. metalloid f. metal

32. Metals are generally dense,solid, shiny, ductile,malleable, and goodconductors of heat andelectricity.

33. a. 2; b. 4; c. 3; d. 134. a. rep.; b. rep.; c. rep.;

d. trans.; e. rep.; f. trans.35. See the Solutions Manual

for a sample table.

36. properties describe a metal; left of thestair step line

37. Metalloids have properties interme-diate between metals and nonmetals.(B, Si, Ge, As, Sb, Te, Po, At) are metal-loids.

38. The line separates metals fromnonmetals. Most elements borderingthe line are metalloids.

CHAPTERASSESSMENT 6

All Chapter Assessment questionsand answers have been validatedfor accuracy and suitability byThe Princeton Review.


Chapter Assessment, pp. 31–36 Supplemental Problems, Ch. 6TestCheck SoftwareMindJogger VideoquizzesSolutions Manual, Ch. 6Chemistry Interactive CD-ROM, Ch. 6 quiz

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Assessment 175

CHAPTER 6 ASSESSMENT

51. Explain why the radius of an atom cannot be measureddirectly. (6.3)

52. Given any two elements within a group, is the elementwith the larger atomic number likely to have a largeror smaller atomic radius than the other element? (6.2)

53. Which elements are characterized as having their dorbitals fill with electrons as you move left-to-rightacross a period? (6.2)

54. Explain why is it harder to remove an inner shell elec-tron than a valence electron from an atom. (6.3)

55. An element forms a negative ion when ionized. Onwhat side of the periodic table is the element located?Explain. (6.3)

56. Of the elements magnesium, calcium, and barium,which forms the ion with the largest radius? Thesmallest? What periodic trend explains this? (6.3)

57. What is ionization energy? (6.3)

58. Explain why each successive ionization of an electronrequires a greater amount of energy. (6.3)

59. Which group has the highest ionization energies?Explain why. (6.3)

60. Define an ion. (6.3)

61. How does the ionic radius of a nonmetal compare withits atomic radius? Explain why the change in radiusoccurs. (6.3)

62. Explain why atomic radii decrease as you move left-to-right across a period. (6.3)

63. Which element in each pair has the larger ionizationenergy? (6.3)

a. Li, Nb. Kr, Nec. Cs, Li

64. Explain the octet rule. (6.3)

65. Use the illustration of spheres A and B to answer eachof the following questions. Explain your reasoning foreach answer. (6.3)

a. If A is an ion and B is an atom of the same ele-ment, is the ion a positive or negative ion?

b. If A and B represent the atomic radii of two ele-ments in the same period, what is their correctorder (left-to-right)?

c. If A and B represent the ionic radii of two elementsin the same group, what is their correct order (top-to-bottom)?

66. How many valence electrons do elements in each ofthe following groups have? (6.3)

a. group 8Ab. group 3Ac. group 1A

67. Na+ and Mg2+ ions each have ten electrons surround-ing their nuclei. Which ion would you expect to havethe larger radius? Why? (6.3)

Mixed ReviewSharpen your problem-solving skills by answering the following.

68. Match each numbered item on the right with the let-tered item that it is related to on the left.

a. group A elements 1. periodsb. columns 2. representative elementsc. group B elements 3. groupsd. rows 4. transition elements

69. Which element in each pair is more electronegative?

a. K, Asb. N, Sbc. Sr, Be

70. Explain why the s-block of the periodic table is twogroups wide, the p-block is six groups wide, and the d-block is ten groups wide.

71. Arrange the elements oxygen, sulfur, tellurium, andselenium in order of increasing atomic radii. Is yourorder an example of a group trend or a period trend?

72. Identify the elements with the following valence elec-tron configurations.

a. 5s1 c. 3s2

b. 4s23d2 d. 4s24p3

73. Which of the following is not a reason why atomicradii increase as you move down a group?a. shielding of inner electronsb. valence electrons in larger orbitalsc. increased charge in the nucleus

74. Explain why there are no p-block elements in the firstperiod of the periodic table.

75. Identify each of the following as an alkali metal, alka-line earth metal, transition metal, or inner transitionmetal.

a. cesium d. ytterbiumb. zirconium e. uraniumc. gold f. francium

76. An element is a brittle solid that does not conductelectricity well. Is the element a metal, nonmetal, ormetalloid?

AA BB

the nucleus by attractive electrostaticforces.

55. Elements on the right side of the periodic table gain electrons to gain a stable octet.

56. Ba2� is the largest; Mg2� is the smallest;ionic size increases down a group.

57. Ionization energy is the energyneeded to remove an electron from aneutral atom in its gaseous state.

58. With each removed electron, there

are fewer electrons to shield theremaining electrons from the electro-static force of attraction of thenucleus. The increased nuclear attrac-tion makes it more difficult to removesubsequent electrons.

59. The group 8A elements have thehighest ionization energies becausetheir electron configurations are themost stable.

60. An ion is an atom or a bonded group

39. One system uses 1A– 8A forrepresentative elements,and 1B–8B for transitionelements. The other systemnumbers the columns 1–18left to right.

40. a. Br, Hg; b. Rn; c. Sn or Pb; d. elements 58–71 or 90–103

41. They have the samevalence electron configura-tion (s2p5).

42. The number of valenceelectrons equals the groupnumber for group Aelements.

43. The energy level of anatom’s valence electronsequals its period number.

44. All noble gases have eightvalence electrons, exceptfor helium, which has two.

45. s-, p-, d-, and f-block46. ns2np6, where n is the

energy level47. a. 3B, period 5, d-block

b. 5A, period 4, p-blockc. 8A, period 2, p-blockd. 3A, period 3, p-block

48. a. trans. metal c. rep.b. rep. d. rep.

49. Elements in a given columnhave the same number ofvalence electrons. Theenergy level of an atom’svalence electrons deter-mines its period.

50. a. Bi: [Xe]6s24f145d106p3

b. Cl: [Ne]3s23p5

c. Li : [He]2s1

d. Hg: [Xe]6s24f145d10

51. because the boundaries ofan atom are indistinct

52. larger 53. transition metals54. There are fewer shielding

electrons between innerelectrons and the nucleus.Thus, the inner electronsare more tightly bound to


Pages 174–1753(A), 3(E), 4(D), 6(A), 6(C)

Thinking Critically77. Interpreting Data Given the following data about

an atom’s ionization energies, predict its valence elec-tron configuration. Explain your reasoning.

78. Applying Concepts Sodium forms a 1+ ion, whilefluorine forms a 1� ion. Write the electron configura-tion for each ion. Why don’t these two elements form2� and 2� ions, respectively?

79. Interpreting Data The melting points of the period6 elements are plotted versus atomic number in thegraph shown below. Determine the trends in meltingpoint by analyzing the graph and the orbital configura-tions of the elements. Form a hypothesis that explainsthe trends. (Hint: In Chapter 5, you learned that half-filled sets of orbitals are more stable than other config-urations of partially filled orbitals.)

80. Making and Using Graphs The densities of thegroup 5A elements are given in the table above. Plotdensity versus atomic number and state any trendsyou observe.

Writing in Chemistry81. In the early 1800s, German chemist J. W. Dobereiner

proposed that some elements could be classified intosets of three, called triads. Research and write a reporton Dobereiner’s triads. What elements comprised thetriads? How were the properties of elements within atriad similar?

82. Electron affinity is another periodic property of theelements. Research and write a report on what electronaffinity is and describe its group and period trends.

Cumulative ReviewRefresh your understanding of previous chapters byanswering the following.

83. Define matter. Identify whether or not each of the fol-lowing is a form of matter. (Chapter 1)

a. microwavesb. helium inside a balloonc. heat from the Sund. velocitye. a speck of dustf. the color blue

84. Convert the following mass measurements as indi-cated. (Chapter 2)

a. 1.1 cm to metersb. 76.2 pm to millimetersc. 11 Mg to kilogramsd. 7.23 micrograms to kilograms

85. How is the energy of a quantum of emitted radiationrelated to the frequency of the radiation? (Chapter 5)

86. What element has the ground-state electron configura-tion of [Ar]4s23d6? (Chapter 5).

Element Atomic Number Density (g/cm3)

nitrogen 7 1.25 � 10�3

phosphorus 15 1.82

arsenic 33 5.73

antimony 51 6.70

bismuth 83 9.78


CHAPTER ASSESSMENT6

Group 5A Density Data

Ionization Data

Ionization Ionization Energy (kJ/mol)

First 734

Second 1850

Third 16 432

55 57 75 77 79 81 83 85 8773

Mel

tin

g p

oin

t (K

)

4000

3000

2000

1000900800700600500

400

300

200

100

Atomic number

Melting Points of the Period 6 Elements

Cs

BaLa

Hf

OsIr

Pt

Au

Hg

PbTlBi Po

At

Rn

Ta ReW

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three p orbitals, which hold amaximum of six electrons. The d-blockrepresents the filling of the five dorbitals, which hold a maximum often electrons.

71. The order is O, S, Se, and Te. This is anexample of a group trend.

72. a. Rb; b. Ti; c. Mg; d. As73. c

74. The p orbital does not exist for energylevel 1. The first energy level consistsonly of a single s orbital that holds amaximum of two electrons.

75. a. alkali metal; b. transition metal;c. transition metal; d. transition metal;e. inner transition metal; f. alkali metal

76. The element is most likely a nonmetal.

of atoms with a positive ornegative charge.

61. The ionic radius of anonmetal is larger than itsneutral atom. Nonmetalstend to gain electrons inthe atom’s current energylevel; these additional elec-trons repel each other andincrease the size of the ion.

62. Atomic radii decrease left-to-right because thenuclear charge increases asthe shielding of inner coreelectrons remains constant.The increased attraction ofthe nucleus for its electronspulls the electrons inward,resulting in a decreasedatomic size.

63. a. N; b. Ne; c. Li64. The ns2np6 electron config-

uration, known as theoctet configuration,contains eight electronsand generally has thelowest energy and is themost stable. Atoms gain,lose, or share electrons inorder to obtain the stableoctet configuration.

65. a. The ion is negative. Anegative ion is alwayslarger than its atom.

b. A is to the left of B. Atomic radius in aperiod decreases left-to-right.

c. A is below B. Ionic radiusincreases down a group.

66. a. 8; b. 3; c. 167. Na� has the larger radius.

The greater nuclear chargeof Mg2� produces anincreased inward pull on itsten electrons and results ina smaller radius.

Mixed Review68. a. 2; b. 3; c. 4; d. 169. a. As ; b. N; c. Be70. The s block represents the

filling of the s orbital,which holds a maximum oftwo electrons. The p-blockrepresents the filling of the


177

Standardized Test Practice 177

Use these questions and the test-taking tip to preparefor your standardized test.

1. Periodic law states that elements show a _____.

a. repetition of their physical properties whenarranged by increasing atomic radius

b. repetition of their chemical properties whenarranged by increasing atomic mass

c. periodic repetition of their properties whenarranged by increasing atomic number

d. periodic repetition of their properties whenarranged by increasing atomic mass

2. Elements in the same group of the periodic table havethe same _____.

a. number of valence electrons b. physical propertiesc. number of electronsd. electron configuration

3. All of the following are true EXCEPT _____.

a. atomic radius of Na < atomic radius of Mgb. electronegativity of C > electronegativity of Bc. ionic radius of Br� > atomic radius of Brd. first ionization energy of K > first ionization

energy of Rb

4. Which of the following is NOT true of an atom obey-ing the octet rule?

a. obtains a full set of eight valence electronsb. acquires the valence configuration of a noble gasc. possesses eight electrons in total d. has a s2p6 valence configuration

5. What is the group, period, and block of an atom withthe electron configuration [Ar]4s23d104p4?

a. group 4A, period 4, d-blockb. group 6A, period 3, p-blockc. group 4A, period 4, p-blockd. group 6A, period 4, p-block

6. Moving down a group on the periodic table, whichtwo atomic properties follow the same trend?

a. atomic radius and ionization energyb. ionic radius and atomic radiusc. ionization energy and ionic radius d. ionic radius and electronegativity

Interpreting Tables Use the periodic table and thetable at the bottom of the page to answer questions 7 and 8.

7. It can be predicted that silicon will experience a largejump in ionization energy after its _____.

a. second ionizationb. third ionizationc. fourth ionization d. fifth ionization

8. Which of the following requires the most energy?

a. second ionization of Lib. fourth ionization of Nc. first ionization of Ned. third ionization of Be

9. Niobium (Nb) is a(n) _____.

a. nonmetal c. alkali metalb. transition metal d. halogen

10. It can be predicted that element 118 would have prop-erties similar to a(n) _____.

a. alkali earth metal c. metalloidb. halogen d. noble gas

STANDARDIZED TEST PRACTICECHAPTER 6

Practice, Practice, Practice Practice toimprove your performance on standardized tests.Don’t compare yourself to anyone else.

Successive Ionization Energies for the Period 2 Elements

ElementValence Ionization energy (kJ/mol)*

electrons 1st 2nd 3rd 4th 5th 6th 7th 8th 9th

Li 1 520 7300

Be 2 900 1760 14 850

B 3 800 2430 3660 25 020

C 4 1090 2350 4620 6220 37 830

N 5 1400 2860 4580 7480 9440 53 270

O 6 1310 3390 5300 7470 10 980 13 330 71 330

F 7 1680 3370 6050 8410 11 020 15 160 17 870 92 040

Ne 8 2080 3950 6120 9370 12 180 15 240 20 000 23 070 115 380

* mol is an abbreviation for mole, a quantity of matter.

Cumulative Review83. Matter is anything that has mass and

takes up space.a. no d. nob. yes e. yesc. no f. no

84. a. 1.1 � 10�2 mb. 7.62 � 10�8 mmc. 1.1 � 104 kgd. 7.23 � 10�9 kg

85. The energy of a quantum equals thefrequency times Planck’s constant.

86. iron

Standardized Test Practice1. c 6. b2. a 7. c3. a 8. d4. c 9. b5. d 10. d

Thinking Critically77. It’s a 2A element with a

ns2 configuration. The two s electrons are easilyremoved, but the thirdelectron must be removedfrom the (n-1) p orbital,which is much more tightlyheld.

78. Both ions have the configu-ration 1s22s22p6, a stable,noble gas configuration.

79. For the d-block elements,the highest values occur forhalf-filled and near half-filled d orbitals. (Re with aconfiguration of 5d5 hasthe highest melting point.)Relating to Hund’s rule, it seems that metallicbonding strengthens as the number of unpairedelectrons increases, reach-ing a maximum when theorbital is half-filled. Notethat Hg and Rn have nounpaired electrons andsubstantially lower meltingpoints. For the p-blockelements (81–86), again theelements with unpaired p electrons tend to havehigher melting points.

80. The graph should showdensity increasing withincreasing atomic number.Note that the density ofnitrogen is so low becauseit is the only element thatexists as a gas (the othersare solids). See theSolutions Manual forgraph.


Pages 176–1772(D), 2(E), 3(E), 4(C), 4(D), 6(A),6(C)

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