E X P L O R I N G

THE WORLD OF C H E M I ST RYFirst printing, September 2001Fourth printing, July 2006

Copyright © 2001 by Master Books

All rights reserved. No part of this book may be used or reproduced in any mannerwhatsoever without written permission of the publisher except in the case of briefquotations in articles and reviews.

For information write: Master Books,P.O. Box 726, Green Forest, AR 72638

ISBN-10: 978-0-89051- 295-1 Library of Congress: 00-102649ISBN-10: 0-89051-295-7Interior Design by Bryan Miller

Printed in the United States of America.

This book is dedicated to Samuel Conner Stephens

THE WORLD OF C H E M I ST RY

All illustrations by Bryan Miller unless otherwise noted.James W. Young 5The Beinecke Rare Book and Manuscript Library: 23NASA: 30Mary Evans Picture Library: 38The Complete Encyclopedia of Illustration: 56, 97National Library of Medicine: 88Image Club, Object Year, CD: 101

Chapter 1: Ancient Metals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Chapter 2: The Money Metals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

Chapter 3: The Search for Gold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18

Chapter 4: Gases in the Air . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28

Chapter 5: Electricity to the Rescue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36

Chapter 6: Search for Order . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44

Chapter 7: Sunlight Shows the Way . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52

Chapter 8: The Electron Shows the Way . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .62

Chapter 9: Compounds by Electric Attraction . . . . . . . . . . . . . . . . . . . . . . . . . .70

Chapter 10: Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .78

Chapter 11: Carbon and Its Compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .86

Chapter 12: Organic Chemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .96

Chapter 13: Nitrogen and Its Compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .104

Chapter 14: Silicon and Its Compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .112

Chapter 15: Modern Metals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .120

Chapter 16: Chemistry in Today’s World . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .128

Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .136

Answers to Chapter Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .137

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .138

Metals such as iron, lead, and tinwere important to ancient people. Theymade tools, spears, shields, dinnerware,and even mirrors from metals. Iron isone of the metals used for centuries.Some ancient civiliza-tions had tools made ofiron although they didnot have the skill toextract iron from itsore. Where did theyget the iron?

One clue to theanswer came whenEuropeans settled inthe New World. Theydiscovered that a fewtribes of Aztec Indiansof South America hadtools and knives madeof iron. The Aztecs,like the ancient civiliza-tions, did not knowhow to smelt iron.Where did the ironcome from? The Aztecsexplained that rocks

A C T I O NA C T I O N1. Ancient people had iron

tools.

2. Iron resisted efforts toremove it from its ore.

3. The Scott expedition tothe South Pole perished ina blizzard when their fuelcans were found empty.

C a n Yo u P r e d i c tC a n Yo u P r e d i c tt h e Re a c t i o n s ?t h e Re a c t i o n s ?

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containing pure iron fell from the sky.They prized the metal more than gold.

The French Academy, a powerful andrespected group of scientists, completelydiscounted the report of falling rocks.Antoine Lavoisier, a famous French scien-tist, insisted, “The fall of stones from thesky is physically impossible.”

Once, an old French clergyman cameto the Paris Museum with a stone that hedescribed as having fallen from the sky.

“No,” the museum curator said. “Youmust be mistaken. You should know better.Rocks can’t fall from the sky because thereare none up there to fall.”

The clergyman asked the academy toinvestigate anyway. A committee of severalrespected chemists and geologists studiedthe rocks. They replied, “We regret thatin our enlight-ened age therestill are people sosuperstitious as tobelieve stones fallfrom the sky. Thispeculiar-looking stoneis nothing more thansoil which has beenstruck by lightning.”

In 1790, the FrenchAcademy of Sciences evenpassed a resolution aboutthe subject. They wouldno longer investigatereports of objectsfalling from the sky.

Many museum direc-tors read the academy’sreport. Did they have anyof the stones? Peopleclaimed to have seenobjects streak throughthe sky like a flash oflightning. Sometimesthe object fell to earth

with an ear-shattering bang. They donatedthe stones to the museums. Museum direc-tors searched through their geology displaysfor the blackened stones. They found therocks and hid them from sight.

In 1807 the American chemistBenjamin Silliman saw such an object fall.

He reported to the president of theUnited States, Thomas Jefferson. The

professor invited President Jeffersonto come to the field and see for

himself the stone that hadburied itself upon impact.

President Jefferson wasan amateur scientist

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Ancient weapons

Leonid Fire Ball

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The Egyptians became desperate foriron. One of the rulers of Egypt offeredthe Hittites an exchange of gold for iron.The Hittites refused, so the Egyptianshad to learn to smelt iron themselves.

Coaching iron from its ore is noteasy because it is so tightly bound. TheEgyptian metal workers believed the orewould release the iron in a hot furnace,the hotter the better. First, they bakedwood in closed ovens. Charcoal wasformed when wood was heated withoutoxygen. Charcoal was rich in carbon andburned even hotter than wood. Next,they made a small blast furnace by tip-ping hollow reeds with clay. They blewthrough the reeds, sending oxygenthrough a charcoal and iron ore mixture.

The Egyptian blast furnace worked.

They got iron from iron ore.Chemists know now that charcoal

does more than merely generate heat. Ittakes part in the chemical reaction thatreleases iron from its ore. Iron ore con-tains iron combined with oxygen. Duringsmelting, carbon from charcoal frees ironfrom oxygen’s grip by combining withthe oxygen.

Iron produced in this way is castiron. It has impurities, including carbonfrom the charcoal. Cast iron is hard, butbrittle. A sudden blow can shatter it.

The Egyptians learned to remove theimpurities by heating cast iron with moreiron ore and limestone. The result waswrought iron, a pure form of the metal.It is soft and easily hammered into shape,but is much too soft for most purposes.

How Egyptians Made Iron

and a very knowledgeable individual. Hedeclined the invitation. “I find it easier tobelieve that a Yankee professor would liethan that stones would fall from heaven.”

Benjamin Silliman investigatedfurther. He discovered many honestand dependable people who backed himup. The people claimed they had foundrocks that were still hot enough to blistertheir fingers. Finally, Benjamin Sillimanwrote a book describing the fiery objects.Most American scientists did notbelieve him.

Rocks did fall from the sky. Theystill do! The objects come from space andare called meteorites by today’s scientists.We call them shooting stars.

Meteorites are from outer space.Most burn up in the earth’s atmosphere.

A few survive their fiery trip and plungeto earth. A shooting star is the glowingtrack in the sky left as a meteor streaksinto the earth’s atmosphere. Some mete-orites are made of rocks, but many aremade almost entirely of iron.

Ancient people found these ironmeteorites and hammered the pure ironinto useful tools. Long before metal work-ers learned to extract iron from its ores,they found meteorites made of almostpure iron. The image of Diana at Ephesusthat “fell down from heaven” in Acts 19:35may possibly be an iron meteorite.

The Hittites are believed to have beenthe first to discover the secret of extractingiron from its ore. Until late in the 1800s,the Bible was the only record of theHittites (Joshua 1:4, for example.) They,

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Modern steel mill

along with the Philistines, held thePromised Land of Canaan against theIsraelites. For a time, the Philistinescaptured the ark of the covenant(1 Samuel 4:10–17).

The Hittites built a greatempire in Asia Minor. Iron isharder than bronze. Othernations outfitted theirarmies with bronzeknives, swords, andshields. They could notstand against iron weapons.Somewhere between brittle castiron and soft wrought iron is themost useful and strongest form ofiron — steel. The iron of theEgyptians contained justenough carbon to make it agood grade of steel.

Egyptian metallurgistsimproved upon it evenmore by quenching it.They heated the ironuntil red-hot andthen suddenly thrustit in cold water. Steeltreated in this way is even stronger andharder than regular steel.

Cast iron, steel, and wrought irondiffer only in the amount of carbon theycontain. Today, structural steel is the mostcommon use of iron. When steel is used asreinforcing rods in concrete, the combinationis both rigid and strong.

Iron is cheap and strong, but combinesreadily with oxygen. The chemical combina-tion of oxygen with a metal or other elementis oxidation. Burning is rapid oxidation. Ironitself will burn under certain conditions. Forinstance, holding a lighted match to finesteel wool causes the steel to burst intoflames. Independence Day sparklers havefine iron particles coated on a metal holder.The tiny iron particles sparkle as they burn.

Steel wool and sparklers burnreadily. The iron in them is spun

very fine. It presents a hugesurface area to the air,

encouraging rapidoxidation.The design of

the human bodytakes advantage of

iron’s ability toreact with oxygen.

Iron is one of theessential elements in

human beings, especiallyin blood. Hemoglobin

carries oxygen from thelungs throughout the body.The iron atoms in hemo-globin readily accept oxy-gen atoms from the lungs,and release the oxygen tothe cells of body tissues. Itis oxygen-bearing hemoglo-bin that gives blood itsred color.

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Although commonly knows as a “tin” can, thispopular food container is actually a thin layer oftin plated over steel.

Sparklers have fine ironparticles coated on metalholders that sparkle whenthey burn.

Larger pieces of iron do not burst intoflames, but they react to oxygen nonetheless.Rust is a form of slow oxidation. Althoughmany other metals rust, the oxide coatingoften protects the metal underneath. This isnot the case with iron rust. It flakes away toexpose a new layer to the air. Rust continuesto do its damage.

Painting prevents rust, or iron can becoated with anothermetal such as tin toprotect it. AnEnglishman, PeterDurand, patented thetin can in 1810. Tin isnontoxic and doesnot discolor food. Athin layer of tin isplated over steel. Atin can is a steel cancoated with a layer oftin only 1/250 of aninch thick. A tin canis mostly steel, nottin.

Tin is anotherof the seven ancientmetals. During earlyBible times peopleused tin in alloyswith copper and lead.Bronze is an alloy ofcopper with tin.Another importantalloy is pewter, a bright and shiny combi-nation of tin with lead. People once usedpewter to make cheap kitchen utensils andtableware as a look-alike substitute forexpensive silver dishes.

The common name for ordinary metal-lic tin is white tin. As pure tin gets cold, itundergoes a dramatic change in its physicalproperties. It turns gray in color. Gray tinis brittle.

Once, in Russia, tin buttons vanishedfrom soldiers’ uniforms. When the quarter-master opened boxes of spare buttons, hefound nothing but gray powder. During thelong Siberian winter, bitterly cold weatherhad changed white tin to gray tin.

One of the great tragedies ofAntarctic exploration came about becauseof tin used to solder the seams of kerosene

cans. Captain RobertScott, a Britishexplorer, organized anexpedition to try to bethe first to reach theSouth Pole. He led hisparty across 1,800miles of ice and snow.At regular intervals,they stored fuel andfood for their return.They reached theSouth Pole onJanuary 18, 1912.Standing on the spotwas a marker left thereone month earlier byRoald Amundsen, aNorwegian explorer.

Disheartened, themen began theirreturn journey into theface of a blizzard.When the weary menarrived at food and

fuel, the tin had turned to powder. Thekerosene leaked through the seams. Thedesperate men raced to the next cache. Thecans there were empty, too. The entire Scottparty perished in the frozen wilderness,partly because of the little-known fact thattin becomes brittle at cold temperatures.

Tin can be beaten into thin sheets andused as tin foil to wrap foods, especiallychocolate candy. However,

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British explorer Robert F. Scott led a tragicexpedition in 1912 in an effort to be the firstto reach the South Pole.

aluminum will do as well,and the cheaper aluminumhas replaced tin. Somepeople still use the term“tin foil” when actuallythey mean aluminum foil.

For some reason,people think of tin as acheap metal, although it isnot cheap. They called thefirst automobiles tinlizzies. People say thatcheap radios with poorquality speakers have atinny sound.

People often use the ancientmetals as figures of speech. Forinstance, a king may rule with a fistof iron. A determinedperson may be described as having a willof iron. A runner who has become wearyis said to have leaden feet. Lead is a heavymetal. When we grow sleepy, we haveleaden eyelids because we barely can keepthem open. Lead is easily worked intosheets, and rolled into pipes. People ofancient times used lead for water pipes.The Roman name for lead is plumbum,the word from which plumber getsits name.

Lead, tin, and iron are three of theseven ancient metals. They are knownas the working metals because of theireveryday uses.

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Ancient lead pipe

R E A C T I O NR E A C T I O N1. Some meteorites that fell to

earth contained pure iron.

2. In a blast furnace, carbonin charcoal combined withoxygen in iron ore to freethe pure metal.

3. In the extremely coldweather, cans sealed withtin leaked their preciousheating fuel.

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1. Ancient people hammered the soft, pure iron from _______________ into useful tools.

A–D 2. Charcoal is (A. a meteorite that fell from the heavens; B. a type of coal found inthe earth; C. made of almost pure oxygen; D. wood that has been heated without oxygen).

T F 3. The only purpose of carbon in smelting iron from its ore is so it will burn andsupply heat.

A–D 4. Which of these forms of iron is the purest? (A. cast iron; B. charcoal;C. steel; D. wrought iron).

A–B 5. Cast iron is (A. brittle and will shatter if struck; B. soft and easily hammeredinto shape).

A–D 6. Steel is quenched by (A. burying it in the earth; B. heating it in an oven forseveral days; C. heating it white hot and thrusting it into cold water; D. raising itoverhead for lightning to strike).

7. Cast iron, steel, and wrought iron differ only in the amount of _______________they contain.

A–B 8. Rusting is a (A. slow; B. rapid) oxidation.

A–B 9. A tin can is made mostly of (A. tin; B. steel).

A–D 10. The one that looks more like silver is (A. brass; B. bronze;C. gold; D. pewter).

T F 11. Metals maintain their properties regardless of temperature.

A–B 12. The more expensive metal is (A. aluminum; B. tin).

Answer T or F for true or false; select A, B, C, or D; or fill in theblank for the phrase that best completes the sentence.

Ancient MetalsAncient Metals