the periodic table - template.net · test your pattern by gathering ... copyright © by holt,...

300 Chapter 12

Arranging the Elements. . . . . . . . . . . 302

QuickLab . . . . . . . . . . 307Apply . . . . . . . . . . . . . 308Internet Connection . . 309

Grouping the Elements. . . . . . . . . . . 310

Internet Connect . . . . 313Environment

Connection . . . . . . . . 314

Chapter Review . . . . . . . . . 320

Feature Articles . . . . . . 322, 323

LabBook . . . . . . . . . . . 678–679

The PeriodicTableThe PeriodicTable

A building as a Piece of Art!Would you believe that this strange-looking building is anart museum? It is! It’s the Guggenheim Museum in Bilbao,Spain. The building is made of limestone blocks, glass, andthe element titanium. Titanium was chosen because it isstrong, lightweight, and very resistant to corrosion andrust. In fact, the half-millimeter-thick fish-scale titaniumpanels covering most of the building are guaranteed to last100 years! In this chapter, you will learn about some otherelements on the periodic table and their properties.

Pre-ReadingQuestions

1. How are elements organized in the periodictable?

2. Why is the table of the elements called “periodic”?

3. What one property isshared by elements in a group?

Copyright © by Holt, Rinehart and Winston. All rights reserved.

301

PLACEMENT PATTERN In this activity, you will determinethe pattern behind a new seatingchart your teacher has created.

Procedure

1. In your ScienceLog, draw a seatingchart for the classroom arrange-ment given to you by your teacher.Write the name of each of yourclassmates in the correct place onthe chart.

2. Write information about yourself,such as your name, date of birth,hair color, and height, in the spacethat represents you on the chart.

3. Starting with the people aroundyou, gather the same informationabout them. Write each person’sinformation in the proper space onthe seating chart.

Analysis

4. In your ScienceLog, identify a pat-tern to the information you gath-ered that might explain the orderof the people in the seating chart.If you cannot find a pattern, collectmore information and look again.

5. Test your pattern by gatheringinformation from a person you didnot talk to before.

6. If the new information does notsupport your pattern, reanalyze yourdata and collect more informationto determine another pattern.

The Periodic TableCopyright © by Holt, Rinehart and Winston. All rights reserved.

Chapter 12302

Arranging the ElementsImagine you go to a new grocery store to buy a box of cereal.You are surprised by what you find. None of the aisles arelabeled, and there is no pattern to the products on the shelves!You think it might take you days to find your cereal.

Some scientists probably felt a similar frustration before1869. By that time, more than 60 elements had been discoveredand described. However, it was not until 1869 that the el-ements were organized in any special way.

Discovering a PatternIn the 1860s, a Russian chemist named Dmitri Mendeleevbegan looking for patterns among the properties of the

elements. He wrote the names and properties of the elements on pieces of paper. He included density, appear-

ance, atomic mass, melting point, and informationabout the compounds formed from the element. He

then arranged and rearranged the pieces of paper, asshown in Figure 1. After much thought and work,

he determined that there was a repeatingpattern to the properties of the elements

when the elements were arranged inorder of increasing atomic mass.

The Properties of Elements Are Periodic Mendeleev sawthat the properties of the elements were periodic, meaning theyhad a regular, repeating pattern. Many things that are famil-iar to you are periodic. For example, the days of the week areperiodic because they repeat in the same order every 7 days.

When the elements were arranged in order of increasingatomic mass, similar chemical and physical properties wereobserved in every eighth element. Mendeleev’s arrangementof the elements came to be known as a periodic table becausethe properties of the elements change in a periodic way.

Section

1

periodic periodperiodic law group

◆ Describe how elements arearranged in the periodic table.

◆ Compare metals, nonmetals, and metalloids based on theirproperties and on their locationin the periodic table.

◆ Describe the difference betweena period and a group.

Figure 1 By playing “chemical solitaire”on long train rides, Mendeleev organizedthe elements according to their properties.



Predicting Properties of Missing Elements Look at thesection of Mendeleev’s periodic table shown in Figure 2. Noticethe question marks. Mendeleev recognized that there were el-ements missing and boldly predicted that elements yet to bediscovered would fill the gaps. He also predicted the propertiesof the missing elements by using the pattern of properties inthe periodic table. When one of the missing elements, gal-lium, was discovered a few years later, its properties matchedMendeleev’s predictions very well. Since that time, all of themissing elements on Mendeleev’s periodic table have been dis-covered. In the chart below, you can see Mendeleev’s predic-tions for another missing element—germanium—and the actualproperties of that element.

Changing the ArrangementMendeleev noticed that a few elements in the table were notin the correct place according to their properties. He thoughtthat the calculated atomic masses were incorrect and that moreaccurate atomic masses would eventually be determined.However, new measurements of the atomic masses showedthat the masses were in fact correct.

The mystery was solved in 1914 by a British scientist namedHenry Moseley (MOHZ lee). From the results of his experi-ments, Moseley was able to determine the number of pro-tons—the atomic number—in an atom. When he rearrangedthe elements by atomic number, every element fell into itsproper place in an improved periodic table.

Since 1914, more elements have been discovered. Each dis-covery has supported the periodic law, considered to be thebasis of the periodic table. The periodic law states that thechemical and physical properties of elements are periodicfunctions of their atomic numbers. The modern version of theperiodic table is shown on the following pages.

The Periodic Table 303

Figure 2 Mendeleev used ques-tion marks to indicate someelements that he believed would later be identified.

Moseley was 26 when hemade his discovery. Hiswork allowed him to predictthat only three elementswere yet to be foundbetween aluminum andgold. The following year, ashe fought for the British inWorld War I, he was killed inaction at Gallipoli, Turkey.The British government nolonger assigns scientists tocombat duty.

Properties of Germanium

Mendeleev’s Actual predictions properties

Atomic mass 72 72.6

Density 5.5 g/cm3 5.3 g/cm3

Appearance dark gray metal gray metal

Melting point high melting point 937�C


140.1

232.0

140.9

231.0

144.2

238.0

(144.9)

(237.0)

150.4

244.1

6.9

23.0

39.1

85.5

132.9

(223.0)

9.0

24.3

40.1

87.6

137.3

(226.0)

45.0

88.9

138.9

(227.0)

47.9

91.2

178.5

(261.1)

50.9

92.9

180.9

(262.1)

52.0

95.9

183.8

(263.1)

54.9

(97.9)

186.2

(262.1)

55.8

101.1

190.2

(265)

58.9

102.9

192.2

(266)

1.0

Praseodymium

Rutherfordium

Molybdenum

Lithium

Sodium

Potassium

Rubidium

Cesium

Francium

Cerium

Thorium Protactinium

Neodymium

Uranium

Promethium

Neptunium

Samarium

Plutonium

Beryllium

Magnesium

Calcium

Strontium

Barium

Radium

Scandium

Yttrium

Lanthanum

Actinium

Titanium

Zirconium

Hafnium

Vanadium

Niobium

Tantalum

Dubnium

Chromium

Tungsten

Seaborgium

Manganese

Technetium

Rhenium

Bohrium

Iron

Ruthenium

Osmium

Hassium

Cobalt

Rhodium

Iridium

Meitnerium

Hydrogen

Li

V

Na

K

Rb

Cs

Fr

Be

Mg

Ca

Sr

Ba

Ra

Sc

Y

La

Ac

Ti

Zr

H f

Rf

Nb

Ta

Db

Cr

Mo

W

Sg

Mn

Re

Bh

IrOs

Ce

Th

Pr

Pa

Nd

U

Pm

Np

Sm

Pu

Fe

Ru

Hs

Co

Rh

Mt

H

Tc

3

11

19

37

55

87

58

90

59

91

60

92

61

93

62

94

4

12

20

38

56

88

21

39

57

89

22

40

72

104

23

41

73

105

24

42

74

106

25

43

75

107

26

44

76 77

108

27

45

109

1

Group 3 Group 4 Group 5 Group 6 Group 7 Group 8 Group 9

Group 1 Group 2

Period 1

Period 2

Period 3

Period 4

Period 5

Period 6

Period 7

Lanthanides

Actinides

Background

Metals

Metalloids

Nonmetals

Chemical symbol

Solid

Liquid

Gas

6

CCarbon

12.0

Periodic Tableof the ElementsEach square on the table includes anelement’s name, chemical symbol,atomic number, and atomic mass.

Atomic number

Chemical symbol

Element name

Atomic mass

Chapter 12304

The color of the chemicalsymbol indicates the physi-cal state at room tempera-ture. Carbon is a solid.

The background colorindicates the type ofelement. Carbon is anonmetal.

A column of el-ements is called a group or family.

A row of elements iscalled a period.

These elements are placed below thetable to allow the table to be narrower.

Background

Metals

Metalloids

Nonmetals

Chemical symbol

Solid

Liquid

Gas

152.0

(243.1)

157.3

(247.1)

158.9

(247.1)

162.5

(251.1)

164.9

(252.1)

167.3

(257.1)

168.9

(258.1)

173.0

(259.1)

175.0

(262.1)

58.7 63.5 65.4 69.7 72.6 74.9 79.0 79.9 83.8

27.0 28.1 31.0 32.1 35.5 39.9

10.8 12.0 14.0 16.0 19.0 20.2

4.0

106.4 107.9 112.4 114.8 118.7 121.8 127.6 126.9 131.3

195.1

(271) (272)

197.0 200.6 204.4 207.2 209.0 (209.0) (210.0) (222.0)

(277)

Europium

Americium

Gadolinium

Curium

Terbium

Berkelium

Dysprosium

Californium

Holmium

Einsteinium

Erbium

Fermium

Thulium

Mendelevium

Ytterbium

Nobelium

Lutetium

Lawrencium

Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton

Aluminum Silicon Phosphorus Sulfur Chlorine Argon

Boron Carbon Nitrogen Oxygen Fluorine Neon

Helium

Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon

Ununnilium Unununium

Platinum Gold Mercury Thallium Lead Bismuth Polonium Astatine Radon

Ununbium

Eu

Am

Gd

Cm

Tb

Bk

Dy

Cf

Pd Ag Cd In Sn Sb Te I Xe

Pt

Uun Uuu

Au Hg Tl Pb Bi Po At Rn

Ho

Es

Er

Fm

Tm

Md

Yb

No

Lu

Lr

Ni Cu Zn Ga Ge As Se Br Kr

Al Si P S Cl Ar

B C N O F Ne

He

Uub

28 29 30 31 32 33 34 35 36

13 14 15 16 17 18

5 6 7 8 9 10

2

46 47 48 49 50 51 52 53 54

78 79 80 81 82 83 84 85 86

110 111

63

95

64

96

65

97

66

98

67

99

68

100

69

101

70

102

71

103

112

Group 13 Group 14 Group 15 Group 16 Group 17

Group 18

Group 10 Group 11 Group 12


A number in parentheses is the mass numberof the most stable isotope of that element.

The names and symbols of elements 110–112 aretemporary. They are based on the atomic number ofthe element. The official name and symbol will beapproved by an international committee of scientists.

This zigzag linereminds you wherethe metals, nonmetals,and metalloids are.

TOPIC: Periodic TableGO TO: go.hrw.comKEYWORD: HN0 Periodic

Visit the HRW Web site to see the most recent version of the periodic table.


Finding Your Way Around the Periodic TableAt first glance, you might think studying the periodic table islike trying to explore a thick jungle without a guide—it wouldbe easy to get lost! However, the table itself contains a lot ofinformation that will help you along the way.

Classes of Elements Elements are classified as metals,nonmetals, and metalloids, according to their properties. Thenumber of electrons in the outer energy level of an atomalso helps determine which category an element belongs in.The zigzag line on the periodic table can help you recog-nize which elements are metals, which are nonmetals, andwhich are metalloids.

Most elements are metals. Metals arefound to the left of the zigzag line on theperiodic table. Atoms of most metalshave few electrons in their outer energylevel, as shown at right.

Most metals are solid at room tem-perature. Mercury, however, is a liquid.Some additional information on propertiesshared by most metals is shown below.

Metals

A model of amagnesium atom

Most metals are malleable, meaningthat they can be flattened with a hammer without shattering.Aluminum is flattened into sheets to make cans and foil.

306

Most metals are ductile,which means that they can be drawn into thin wires. Allmetals are good conductors of electric current. The wires in the electrical devices in your home are made from the metal copper.

Chapter 12

Metals tend to be shiny. Youcan see a reflection in a mirrorbecause light reflects off theshiny surface of a thin layer of silver behind the glass.

Most metals are goodconductors of thermalenergy. This iron griddleconducts thermal energyfrom a stovetop to cookyour favorite foods.




Nonmetals are found to the right of thezigzag line on the periodic table. Atoms ofmost nonmetals have an almost completeset of electrons in their outer level, asshown at right. (Atoms of one group ofnonmetals, the noble gases, have a com-plete set of electrons, with most havingeight electrons in their outer energy level.)

More than half of the nonmetals aregases at room temperature. The prop-erties of nonmetals are the opposite ofthe properties of metals, as shown below.

Nonmetals

Metalloids, also called semiconductors,are the elements that border the zigzagline on the periodic table. Atoms of met-alloids have about a half-complete set ofelectrons in their outer energy level, asshown at right.

Metalloids have some properties ofmetals and some properties of nonmetals,as shown below.

Metalloids

A model of asilicon atom

A model of achlorine atom

Nonmetals are not malleable or ductile. In fact, solid nonmetals, like carbon (shown here in the graphite of the pencil lead), are brittle and will break or shatter when hit with a hammer.

Tellurium is shiny, but it is also brittleand is easily smashed into a powder.

Boron is almost ashard as diamond, butit is also very brittle.At high temperatures,boron is a goodconductor of electriccurrent.

Sulfur, like most nonmetals,is not shiny.

Nonmetals are poor conductorsof thermal energy and electriccurrent. If the gap in a sparkplug is too wide, the non-

metals nitrogen and oxygen in the air will stop the spark,

and a car’s engine will not run.

Conduction Connection

1. Fill a plastic-foamcup with hot water.

2. Stand a piece ofcopper wire and agraphite lead froma mechanical pencil in thewater.

3. After 1 minute, touch thetop of each object. Recordyour observations.

4. Which material conductedthermal energy the best?Why?

Each Element Is Identified by a Chemical Symbol Eachsquare on the periodic table contains information about anelement, including its atomic number, atomic mass, name, andchemical symbol. An international committee of scientists isresponsible for approving the names and chemical symbols ofthe elements. The names of the elements come from manysources. For example, some elements are named after impor-tant scientists (mendelevium, einsteinium), and others arenamed for geographical regions (germanium, californium).

The chemical symbol for each element usually consists ofone or two letters. The first letter in the symbol is always cap-italized, and the second letter, if there is one, is always writ-ten in lowercase. The chart below lists the patterns that thechemical symbols follow, and the Activity will help you inves-tigate two of those patterns further.

Chapter 12308

Writing the Chemical Symbols

You can create your own well-rounded periodic table using

coins, washers, and buttons onpage 678 of the LabBook.

Pattern of chemical symbols

first letter of the name

first two letters of the name

first letter and third or laterletter of the name

letter(s) of a word other thanthe English name

first letter of root words thatstand for the atomic number(used for elements whose offi-cial names have not yet beenchosen)

Examples

S—sulfur

Ca—calcium

Mg—magnesium

Pb—lead (from the Latinplumbum, meaning “lead”)

Uun—ununnilium (uhn uhn NIL ee uhm) (foratomic number 110)

Draw a line down a sheet of paper to divide it into twocolumns. Look at the el-ements with atomic numbers1 through 10 on the periodictable. Write all the chemicalsymbols and names that fol-low one pattern in one col-umn on your paper and allchemical symbols and namesthat follow a second patternin the second column. Writea sentence describing eachpattern you found.

One Set of SymbolsLook at the periodic table shown here.How is it the same as the periodictable you saw earlier? How is it differ-ent? Explain why it is important forscientific communication that thechemical symbols used are the samearound the world.



Rows Are Called Periods Each horizontal row of elements(from left to right) on the periodic table is called a period. Forexample, the row from lithium (Li) to neon (Ne) is Period 2. A row is called a period because the properties of elementsin a row follow a repeating, or periodic, pattern as you move across each period. The physical and chemical prop-erties of elements, such as conductivity and the number ofelectrons in the outer level of atoms, change gradually fromthose of a metal to those of a nonmetal in each period, asshown in Figure 3.

Columns Are Called Groups Each column of elements(from top to bottom) on the periodic table is called a group.Elements in the same group often have similar chemical andphysical properties. For this reason, sometimes a group is alsocalled a family. You will learn more about each group in thenext section.

Figure 3 The elements in a row become lessmetallic from left to right.

1. Compare a period and a group on the periodic table.

2. How are the elements arranged in the modern periodictable?

3. Comparing Concepts Compare metals, nonmetals, andmetalloids in terms of their electrical conductivity.


To remember that a periodgoes from left to rightacross the periodic table,just think of reading a sen-tence. You read from left toright across the page untilyou come to a period.

REVIEW

Elements at the left end of aperiod, such as titanium, arevery metallic in their properties.

Elements farther to theright, like germanium, are less metallic in theirproperties.

Elements at the far right endof a period, such as bromine,are nonmetallic in their properties.

VK Ca Sc Ti Cr Mn Fe Co19 20 21 22 23 24 25 26 27

Ni Cu Zn Ga Ge As Se Br Kr28 29 30 31 32 33 34 35 36

47.9Titanium

Ti22

72.6Germanium

Ge32

79.9Bromine

Br35

NSTA

TOPIC: The Periodic TableGO TO: www.scilinks.orgsciLINKS NUMBER: HSTP280

Chapter 12310

Grouping the ElementsYou probably know a family with several members that looka lot alike. Or you may have a friend whose little brother orsister acts just like your friend. Members of a family often—but not always—have a similar appearance or behavior.Likewise, the elements in a family or group in the periodictable often—but not always—share similar properties. The prop-erties are similar because the atoms of the elements have thesame number of electrons in their outer energy level.

Groups 1 and 2: Very Reactive MetalsThe most reactive metals are the elements in Groups 1 and 2.What makes an element reactive? The answer has to do withelectrons in the outer energy level of atoms. Atoms will oftentake, give, or share electrons with other atoms in order to havea complete set of electrons in their outer energy level. Elementswhose atoms undergo such processes are reactive and combineto form compounds. Elements whose atoms need to take, give,or share only one or two electrons to have a filled outer leveltend to be very reactive.

The elements in Groups 1 and 2 are so reactive that theyare only found combined with other elements in nature. Tostudy the elements separately, the naturally occurringcompounds must first be broken apart through chemicalchanges.

Group 1: Alkali Metals

Alkali (AL kuh LIE) metals aresoft enough to be cut with aknife, as shown in Figure 4. Thedensities of the alkali metalsare so low that lithium,sodium, and potassium areactually less dense than water.

Group contains: MetalsElectrons in the outer level: 1Reactivity: Very reactiveOther shared properties: Soft; silver-colored; shiny;low density

Lithium

Sodium

Potassium

Rubidium

Cesium

Francium

Li

Na

K

Rb

Cs

Fr

3

11

19

37

55

87 Figure 4 Metals so soft thatthey can be cut with a knife?Welcome to the alkali metals.

Although the elementhydrogen appears above thealkali metals on the periodictable, it is not considered amember of Group 1. It willbe described separately at

the end of this section.

Section

2

alkali metalsalkaline-earth metalshalogensnoble gases

◆ Explain why elements in a groupoften have similar properties.

◆ Describe the properties of theelements in the groups of theperiodic table.



Alkali metals are the most reactive of the metals. This isbecause their atoms can easily give away the single electronin their outer level. For example, alkali metals react violentlywith water, as shown in Figure 5. Alkali metals are usuallystored in oil to prevent them from reacting with water andoxygen in the atmosphere.

The compounds formed from alkali metals have many uses.Sodium chloride (table salt) can be used to add flavor to yourfood. Sodium hydroxide can be used to unclog your drains.Potassium bromide is one of several potassium compoundsused in photography.

Group 2: Alkaline-earth Metals

Alkaline-earth metals are not as reactive as alkalimetals because it is more difficult for atoms to giveaway two electrons than to give away only onewhen joining with other atoms.

The alkaline-earth metal magnesium is oftenmixed with other metals to make low-densitymaterials used in airplanes. Compounds ofalkaline-earth metals also have many uses.For example, compounds of calcium arefound in cement, plaster, chalk, and evenyou, as shown in Figure 6.

Figure 5 As alkali metals react with water, they form hydrogen gas.

Group contains: MetalsElectrons in the outer level: 2Reactivity: Very reactive, but less reactive than alkalimetalsOther shared properties: Silver-colored; more densethan alkali metals

Beryllium

Magnesium

Calcium

Strontium

Barium

Radium

Be

Mg

Ca

Sr

Ba

Ra

4

12

20

38

56

88

Figure 6 Smile! Calcium, analkaline-earth metal, is animportant component of acompound that makes yourbones and teeth healthy.

311

Lithium PotassiumSodium


Groups 3–12: Transition Metals Groups 3–12 do not have individual names. Instead, thesegroups are described together under the name transition metals.

The atoms of transition metals do not give away their elec-trons as easily as atoms of the Group 1 and Group 2 metalsdo, making transition metals less reactive than the alkali metals and the alkaline-earth metals. The properties of thetransition metals vary widely, as shown in Figure 7.

Some transition metals, including the titanium in the artificial hip at right,are not very reactive. But others, suchas iron, are reactive. The iron in thesteel trowel above has reacted withoxygen to form rust.

Figure 7 Transition metals have a wide range of physical and chemical properties.

Chapter 12312

Group contains: MetalsElectrons in the outer level: 1 or 2Reactivity: Less reactive than alkaline-earth metalsOther shared properties: Shiny; good conductors of thermalenergy and electric current; higher densities and melting points(except for mercury) than elements in Groups 1 and 2

Self-CheckWhy are alkali metals more reactive than alkaline-earth metals? (See page 724 to check your answer.)

Rutherfordium

Molybdenum

Scandium

Yttrium

Lanthanum

Actinium

Titanium

Zirconium

Hafnium

Vanadium

Niobium

Tantalum

Dubnium

Chromium

Tungsten

Seaborgium

Manganese

Technetium

Rhenium

Bohrium

Iron

Ruthenium

Osmium

Hassium

Cobalt

Rhodium

Iridium

Meitnerium

VSc

Y

La

Ac

Ti

Zr

H f

Rf

Nb

Ta

Db

Cr

Mo

W

Sg

Mn

Re

Bh

IrOs

Fe

Ru

Hs

Co

Rh

Mt

Tc

21

39

57

89

22

40

72

104

23

41

73

105

24

42

74

106

25

43

75

107

26

44

76 77

108

27

45

109

Nickel Copper Zinc

Palladium Silver Cadmium

Ununnilium Unununium

Platinum Gold Mercury

Ununbium

Pd Ag Cd

Pt

Uun Uuu

Au Hg

Ni Cu Zn

Uub

28 29 30

46 47 48

78 79 80

110 111 112

Mercury is used in thermometers because,unlike the other transition metals, it is inthe liquid state at room temperature.

Many transition metals aresilver-colored—but not all!This gold ring proves it!


Lanthanides and Actinides Some transitionmetals from Periods 6 and 7 are placed at the bot-tom of the periodic table to keep the table frombeing too wide. The properties of the elements ineach row tend to be very similar.

Elements in the first row are calledlanthanides because they follow thetransition metal lanthanum. The lan-thanides are shiny, reactive metals.Some of these elements are used tomake different types of steel. An impor-tant use of a compound of one lan-thanide element is shown in Figure 8.

Elements in the second row arecalled actinides because they follow thetransition metal actinium. All atoms ofactinides are radioactive, which meansthey are unstable. The atoms of aradioactive element can change intoatoms of a different element. Elementslisted after plutonium, element 94, donot occur in nature but are insteadproduced in laboratories. You mighthave one of these elements in yourhome. Very small amounts of americ-ium (AM uhr ISH ee uhm), element 95,are used in some smoke detectors.


1. What are two properties of the alkali metals?

2. What causes the properties of elements in a group to besimilar?

3. Applying Concepts Why are neither the alkali metals northe alkaline-earth metals found uncombined in nature?

REVIEW

138.9Lanthanum

La57

(227.0)Actinium

Ac89

58

90

59

91

60

92

61

93

62

94

Ce

Th

Pr

Pa

Nd

U

Pm

Np

Sm

Pu

Eu

Am

Gd

Cm

Tb

Bk

Dy

Cf

Ho

Es

Er

Fm

Tm

Md

Yb

No

Lu

Lr

63

95

64

96

65

97

66

98

67

99

68

100

69

101

70

102

71

103

Lanthanides

Actinides

Figure 8 Seeing red? The color red appears on acomputer monitor because of a compound formedfrom europium that coats the back of the screen.

NSTA

TOPIC: MetalsGO TO: www.scilinks.orgsciLINKS NUMBER: HSTP285


Groups 13–16: Groups with MetalloidsMoving from Group 13 across to Group 16, the elements shiftfrom metals to nonmetals. Along the way, you find the met-alloids. These elements have some properties of metals andsome properties of nonmetals.

Group 13: Boron Group

The most common element from Group 13 is alu-minum. In fact, aluminum is the most abundantmetal in Earth’s crust. Until the 1880s, it was con-sidered a precious metal because the process usedto produce pure aluminum was very expensive. Infact, aluminum was even more valuable than gold,as shown in Figure 9.

Today, the process is not as difficult or expen-sive. Aluminum is now an important metal usedin making lightweight automobile parts and air-craft, as well as foil, cans, and wires.

Group 14: Carbon Group

The metalloids silicon and germanium are used tomake computer chips. The metal tin is usefulbecause it is not very reactive. A tin can is reallymade of steel coated with tin. The tin is less reac-tive than the steel, and it keeps the steel from rusting.

Chapter 12314

Group contains: One metalloid and four metalsElectrons in the outer level: 3Reactivity: ReactiveOther shared properties: Solid at room temperature

Gallium

Aluminum

Boron

Indium

Thallium

In

Tl

Ga

Al

B

31

13

5

49

81

Group contains: One nonmetal, two metalloids, andtwo metalsElectrons in the outer level: 4Reactivity: Varies among the elementsOther shared properties: Solid at room temperature

Germanium

Silicon

Carbon

Tin

Lead

Sn

Pb

Ge

Si

C

32

14

6

50

82

Figure 9 During the 1850s and 1860s, EmperorNapoleon III of France used aluminum dinnerwarebecause aluminum was more valuable than gold!

Recycling aluminum uses less energythan obtaining aluminum in the firstplace. Aluminum must be separatedfrom bauxite, a mixture containingnaturally occurring compounds of aluminum. Twenty times moreelectrical energy is required toseparate aluminum from bauxitethan to recycle used aluminum.

EnvironmentC O N N E C T I O N


The nonmetal carbon can be founduncombined in nature, as shown in Figure 10.Carbon forms a wide variety of compounds.Some of these compounds, including pro-teins, fats, and carbohydrates, are essential tolife on Earth.

Group 15: Nitrogen Group

Nitrogen, which is a gas at room temperature,makes up about 80 percent of the air you breathe.Nitrogen removed from air is reacted with hydro-gen to make ammonia for fertilizers.

Although nitrogen is unreactive, phosphorus isextremely reactive, as shown in Figure 11. In fact,phosphorus is only found combined with otherelements in nature.

Group 16: Oxygen Group

Oxygen makes up about 20 percent of air. Oxygenis necessary for substances to burn, such as thechemicals on the match in Figure 11. Sulfur,another common member of Group 16, can befound as a yellow solid in nature. The principaluse of sulfur is to make sulfuric acid, the mostwidely used compound in the chemical industry.

Diamond is the hardest material known.It is used as a jewel and on cutting toolssuch as saws, drills, and files.

Figure 11Simply striking a matchon the side of this boxcauses chemicals onthe match to reactwith phosphorus on the box andbegin to burn.


Group contains: Two nonmetals, two metalloids, andone metalElectrons in the outer level: 5Reactivity: Varies among the elementsOther shared properties: All but nitrogen are solidat room temperature.

Arsenic

Phosphorus

Nitrogen

Antimony

Bismuth

Sb

Bi

As

P

N

33

15

7

51

83

Group contains: Three nonmetals, one metalloid,and one metalElectrons in the outer level: 6Reactivity: ReactiveOther shared properties: All but oxygen are solid atroom temperature.

Selenium

Sulfur

Oxygen

Tellurium

Polonium

Te

Po

Se

S

O

34

16

8

52

84

Soot—formed from burning oil, coal, and wood—is used as a pigment in paints and crayons.

Figure 10 Diamonds andsoot have very differentproperties, yet both arenatural forms of carbon.


Groups 17 and 18: Nonmetals OnlyThe elements in Groups 17 and 18 are nonmetals. The el-ements in Group 17 are the most reactive nonmetals, but theelements in Group 18 are the least reactive nonmetals. In fact,the elements in Group 18 normally won’t react at all withother elements.

Group 17: Halogens

Halogens are very reactive nonmetals because theiratoms need to gain only one electron to have acomplete outer level. The atoms of halogens com-bine readily with other atoms, especially metals,to gain that missing electron.

Although the chemical properties of the halo-gens are similar, the physical properties are quitedifferent, as shown in Figure 12.

Both chlorine and iodine are used as disinfec-tants. Chlorine is used to treat water, while iodinemixed with alcohol is used in hospitals.

Group 18: Noble Gases

Noble gases are unreactive nonmetals. Because theatoms of the elements in this group have a com-plete set of electrons in their outer level, they donot need to lose or gain any electrons. Therefore,they do not react with other elements under nor-mal conditions.

All of the noble gases are found in Earth’satmosphere in small amounts. Argon, the mostabundant noble gas in the atmosphere, makes upalmost 1 percent of the atmosphere.

Figure 12 Physical propertiesof some halogens at roomtemperature are shown here.

316

Group contains: NonmetalsElectrons in the outer level: 7Reactivity: Very reactiveOther shared properties: Poor conductors of electriccurrent; react violently with alkali metals to formsalts; never found uncombined in nature

Bromine

Chlorine

Fluorine

Iodine

Astatine

I

At

Br

Cl

F

35

17

9

53

85

Group contains: NonmetalsElectrons in the outer level: 8 (2 for helium)Reactivity: UnreactiveOther shared properties: Colorless, odorless gasesat room temperature

Krypton

Argon

Neon

Helium

Xenon

Radon

Xe

Rn

Kr

Ar

Ne

He

36

18

10

2

54

86

The term noble gasesdescribes the nonreactivityof these elements. Just asnobles, such as kings andqueens, did not often mixwith common people, thenoble gases do not normallyreact with other elements.

Chapter 12

Chlorine is a yellowishgreen gas.

Bromine is adark red liquid.

Iodine is a darkgray solid.

The nonreactivity of the noble gasesmakes them useful. Ordinary light bulbslast longer when filled with argon thanthey would if filled with a reactive gas.Because argon is unreactive, it does notreact with the metal filament in the lightbulb even when the filament gets hot.The low density of helium causes blimpsand weather balloons to float, and itsnonreactivity makes helium safer to usethan hydrogen. One popular use of noblegases that does not rely on their nonre-activity is shown in Figure 13.

Hydrogen Stands Apart

The properties of hydrogen do not match the properties of anysingle group, so hydrogen is set apart from the other elementsin the table.

Hydrogen is placed above Group 1 in the periodic tablebecause atoms of the alkali metals also have only one elec-tron in their outer level. Atoms of hydrogen, like atoms ofalkali metals, can give away one electron when joining withother atoms. However, hydrogen’s physical properties are morelike the properties of nonmetals than of metals. As you cansee, hydrogen really is in a group of its own.

Hydrogen is the most abundant element in the universe.Hydrogen’s reactive nature makes it useful as a fuel in rockets,as shown in Figure 14. Figure 14 Hydrogen reacts

violently with oxygen. The hotwater vapor that forms as aresult pushes the space shuttleinto orbit.


1. In which group are the unreactive nonmetals found?

2. What are two properties of the halogens?

3. Making Predictions In the future, a new halogen maybe synthesized. Predict its atomic number and properties.

4. Comparing Concepts Compare the element hydrogenwith the alkali metal sodium.

Figure 13 Besides neon, other noble gases are oftenused in “neon” lights.

Electrons in the outer level: 1Reactivity: ReactiveOther properties: Colorless, odorless gas at room tem-perature; low density; reacts explosively with oxygen

REVIEW

HydrogenH1

Argon producesa lavender color.

Xenon producesa blue color.

Neon produces anorange-red color.


Chapter Highlights

Chapter 12318

SECTION 1

Vocabularyperiodic (p. 302)

periodic law (p. 303)

period (p. 309)

group (p. 309)

Section Notes

• Mendeleev developed thefirst periodic table. Hearranged elements in order of increasing atomic mass. The properties of elementsrepeated in an orderly pat-tern, allowing Mendeleev to predict properties for el-ements that had not yet been discovered.

• Moseley rearranged the elements in order of increas-ing atomic number.

• The periodic law states thatthe chemical and physicalproperties of elements areperiodic functions of theiratomic numbers.

• Elements in the periodictable are divided into metals, metalloids, andnonmetals.

• Each element has a chemicalsymbol that is recognizedaround the world.

• A horizontal row of elementsis called a period. The el-ements gradually change from metallic to nonmetallicfrom left to right across eachperiod.

• A vertical column of elementsis called a group or family.Elements in a group usuallyhave similar properties.

LabsCreate a Periodic Table (p. 678)

Skills CheckVisual UnderstandingPERIODIC TABLE OF THE ELEMENTS Scientistsrely on the periodic table as a resource for alarge amount of information. Review theperiodic table on pages 304–305. Pay closeattention to the labels and the key; they will help you understand the informationpresented in the table.

CLASSES OF ELEMENTS Identifying an elementas a metal, nonmetal, or metalloid gives you abetter idea of the properties of that element.Review the figures on pages 306–307 tounderstand how to use thezigzag line on the periodictable to identify the classesof elements and to reviewthe properties of elementsin each category.


SECTION 2

Vocabularyalkali metals (p. 310)

alkaline-earth metals (p. 311)

halogens (p. 316)

noble gases (p. 316)

Section Notes

• The alkali metals (Group 1)are the most reactive metals.Atoms of the alkali metalshave one electron in theirouter level.

• The alkaline-earth metals(Group 2) are less reactivethan the alkali metals. Atomsof the alkaline-earth metalshave two electrons in theirouter level.

• The transition metals(Groups 3–12) include mostof the well-known metals aswell as the lanthanides andactinides located below theperiodic table.

• Groups 13–16 contain themetalloids along with somemetals and nonmetals. Theatoms of the elements ineach of these groups havethe same number of elec-trons in their outer level.

• The halogens (Group 17) arevery reactive nonmetals.Atoms of the halogens haveseven electrons in their outerlevel.

• The noble gases (Group 18)are unreactive nonmetals.Atoms of the noble gaseshave a complete set of elec-trons in their outer level.

• Hydrogen is set off by itselfbecause its properties do notmatch the properties of anyone group.

Visit the National Science Teachers Association on-line Website for Internet resources related to this chapter. Just type inthe sciLINKS number for more information about the topic:

TOPIC: The Periodic Table sciLINKS NUMBER: HSTP280

TOPIC: Metals sciLINKS NUMBER: HSTP285

TOPIC: Metalloids sciLINKS NUMBER: HSTP290

TOPIC: Nonmetals sciLINKS NUMBER: HSTP295

TOPIC: Buckminster Fuller and the Buckyball sciLINKS NUMBER: HSTP300

GO TO: go.hrw.com GO TO: www.scilinks.org

Visit the HRW Web site for a variety oflearning tools related to this chapter. Just type in the keyword:

KEYWORD: HSTPRT

The Periodic Table 319Copyright © by Holt, Rinehart and Winston. All rights reserved.

Chapter ReviewUSING VOCABULARY

Complete the following sentences by choos-ing the appropriate term from each pair ofterms listed below.

1. Elements in the same vertical column inthe periodic table belong to the same ? . (group or period)

2. Elements in the same horizontal row inthe periodic table belong to the same ? . (group or period)

3. The most reactive metals are ? . (alkali metals or alkaline-earth metals)

4. Elements that are unreactive are called ? . (noble gases or halogens)

UNDERSTANDING CONCEPTS

Multiple Choice

5. An element that is a very reactive gas ismost likely a member of thea. noble gases. c. halogens.b. alkali metals. d. actinides.

6. Which statement is true?a. Alkali metals are generally found in

their uncombined form.b. Alkali metals are Group 1 elements.c. Alkali metals should be stored under

water.d. Alkali metals are unreactive.

7. Which statement about the periodic tableis false?a. There are more metals than nonmetals.b. The metalloids are located in Groups 13

through 16.c. The elements at the far left of the table

are nonmetals.d. Elements are arranged by increasing

atomic number.

8. One property of most nonmetals is thatthey area. shiny.b. poor conductors of electric current.c. flattened when hit with a hammer.d. solids at room temperature.

9. Which is a true statement about elements?a. Every element occurs naturally.b. All elements are found in their uncom-

bined form in nature.c. Each element has a unique atomic

number.d. All of the elements exist in approxi-

mately equal quantities.

10. Which is NOT found on the periodictable?a. the atomic number of each elementb. the symbol of each elementc. the density of each elementd. the atomic mass of each element

Short Answer

11. Why was Mendeleev’s periodic table useful?

12. How is Moseley’s basis for arranging theelements different from Mendeleev’s?

13. How is the periodic table like a calendar?

14. Describe the location of metals, metal-loids, and nonmetals on the periodictable.

Chapter 12320Copyright © by Holt, Rinehart and Winston. All rights reserved.

Concept Mapping

15. Use the followingterms to create aconcept map: peri-odic table, elements,groups, periods,metals, nonmetals,metalloids.

CRITICAL THINKING AND PROBLEM SOLVING

16. When an element with 115 protons in itsnucleus is synthesized, will it be a metal,a nonmetal, or a metalloid? Explain.

17. Look at Mendeleev’s periodic table inFigure 2. Why was Mendeleev not able tomake any predictions about the noble gaselements?

18. Your classmate offers to give you a pieceof sodium he found while hiking. What isyour response? Explain.

19. Determine the identity of each elementdescribed below:a. This metal is very reactive, has proper-

ties similar to magnesium, and is in thesame period as bromine.

b. This nonmetal is in the same group as lead.

c. This metal is the most reactive metal inits period and cannot be found uncom-bined in nature. Each atom of the el-ement contains 19 protons.

MATH IN SCIENCE

20. The chart below shows the percentages ofelements in the Earth’s crust.

Excluding the “Other” category, what per-centage of the Earth’s crust isa. alkali metals?b. alkaline-earth metals?

INTERPRETING GRAPHICS

21. Study the diagram below to determine thepattern of the images. Predict the missingimage, and draw it. Identify which prop-erties are periodic and which propertiesare shared within a group.

?fpo

47-A

46.6% O

27.7% Si

2.0% Mg

2.8% Na

3.6% Ca

5.0% Fe

8.1% Al

2.6% K

1.6% Other

321The Periodic Table

Take a minute to reviewyour answers to the Pre-Reading Questionsfound at the bottom

of page 300. Have your answers changed? If necessary, revise your answers based on whatyou have learned since you began this chapter.

ReadingCheck-up


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