Exploring Creation

with

Physical Science 2nd Edition

by Dr. Jay L. Wile

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Exploring Creation With Physical Science, 2nd Edition

Published by Apologia Educational Ministries, Inc.

1106 Meridian Plaza, Suite 220 Anderson, IN 46016 www.apologia.com

Copyright © 2007 Apologia Educational Ministries, Inc. All rights reserved.

Manufactured in the United States of America Sixth Printing, June 2012

ISBN: 978-1-932012-77-4

Printed by Courier, Inc., Kendallville, IN

All Biblical quotations are from the New American Standard Bible (NASE) unless otherwise stated

Cover photos: [agency: Dreamstime.com - glacier © Michael Klenetsky] [agency: Istockphoto.com - cumulus clouds© David Raboin, aurora © Roman Krochuk],

sun and earth courtesy of NASA

Cover design by Kim Williams

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Exploring Creation With Physical Science Table of Contents

MODULE #1: The Basics ....................................................................................................................... I • . Introduction .................................................................................... .... ............. ..... ...... ... ............... ......... 1 Atoms and Molecules ..... .................................................... ... ...... ........... .................. ............................. 1 Experiment 1.1: Atoms and Molecules ......... .... ....................................................... .................. ........... 1 Measurement and Units ............... .................... ....................................... ....... ...... ....... ........................... 7 The Metric System .......... ... ................................... ...... ..... .......... ........................................................... 8 Manipulating Units ............ .............................................. ...... .. ............................................................ 10 Converting Between Units .................. .. ................... ......... ............ .. ....... ............................................. 11 Converting Between Systems ............................................ .... ... ........................................................... 14 Experiment 1.2: Cubits and Fingers ............ ................. ... ..... ....... ......... ......... ... ................................. .. 15 Concentration ..................................................... ... ...... ......... ............................................................... 17 Experiment 1.3: Concentration ........................................................................................................... 17

MODULE #2: Air ................................................................................................................................. 25

Introduction ..... ...... ........... ...................................... ... ..... ........... .......................................................... 25 The Air and Humidity ...... ... ... .......... ................ .......... ....... ........... ............. .... ....... ....... .... .................... 25 Experiment 2.1: Evaporation and Temperature ...................... ............... ..... ... ......... .... ..... ..... ........... ... 25 The Composition of Air ...................................................................................................................... 28 Experiment 2.2: Oxygen and Fire ....................... ........................... ... ......... ........ ... ... ........... ........ .... .... 30 Carbon Dioxide in the Air ... .................. .................. ... ........ ......... ........ .................................. ..... .. .... .... 32 Experiment 2.3: Carbon Dioxide and the Greenhouse Effect.. ....................... .. .... .... .......................... 33 Global Warming ................................. ......... ............................................. ............. .. ........... ..... ... ......... . 36 Parts Per Million ........ .. ....... ..... ..... ..... ..... ........... .......................................................... ......................... 41 Ozone .. ..................................... ................... ..... ... .......................... .... ... ........ ................... .. .. ....... ... ....... 42 Air Pollution .... ......... ....... .... ... ........... ......... ................................................................ .......................... 44

MODULE #3: The Atmosphere .......................................................................................................... 55

Introduction ........................... .............................................................................................................. 55 Atmospheric Pressure ................................................................................................................. .. ....... 55 Experiment 3 .1: Atmospheric Pressure .... ......... ................ ..... .............. .. .. ....... ..................... ..... .......... 56 The Layers of Earth's Atmosphere ..................... ..... .... ................. .. ... .............. .. .................. ....... ..... ... 60 The Homosphere ................................................................................................................................. 62 What Is Temperature? ......... ............... ..... .............. .... .... ... ............ ..................................... .............. .... 66 Experiment 3.2: Seeing the Effect of Changing Temperature .... ............ ... ................ .............. ....... .... 66 The Temperature Gradient in the Homosphere .................. .. ..................... ..... ....... ... ..................... ...... 69 The "Hole" in the Ozone Layer .... ........................ .................... ...... .......... .............................. .... .... .. .... 69 The Heterosphere ..... ........... ..... ............ .......... ... ...... ............................................................... .... .......... 73

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MODULE #4: The Wonder ofWater ................................................................................................. 81

Introduction .... ............ .. ....................................................................................................................... 81 The Composition of Water ..... ... ..... ... ..... ................... ..... ... ... ............... ... ..... ........ .. .......... ... .. ... ......... .. . 81 Experiment 4.1: The Chemical Composition of Water ..... ....... .. .......... ............. ....... ..... ..... ................. 81 Chemical Formulas ......................................... ...... ... .......... ... ......... ... ... .. .................................. ...... ...... 85 Water's Polarity ......... ............. .............. .......... ...... .. .......... ............... .. ..... ......... ..... .... .... ....... ................ 86 Experiment 4.2 : Water's Polarity ... ... ... ..... .. ..... ...... ..... .. ........... .... .... ............. ....... .... ........ ................... 86 Water as a Solvent ..... ...... ..... ... .... .... ......................... ........ .................... ...... .. ..... .......... ...... ...... ....... .. .. . 90 Experiment 4.3: Solvents and Solutes ................... .......................... ... .................. ... ............................ 90 Hydrogen Bonding in Water .................. ......................... ........ ... ... .......... .... ... ............ ......... ... ........ ..... 93 Experiment 4.4: Comparing Solid Water to Solid Butter ............... .. ... .......... ....... .. ................. ....... ... . 95 Water's Cohesion .. .................... .. .......... ...... ..... ... ........ .... .. .... ... .. .. ........................... ... .... ...... ............... 97 Experiment 4.5: Water's Cohesion ...... ... ..... ........... ... ...... ..................... ... .. .... ........ ......... ... .... ... ... .. .. .. .. 97 Experiment 4.6: The Forces Between Molecules .................... .. ........... ... .............................. ..... ......... 99 Hard Water and Soft Water .... .... ....... ............. ... ...... .......... ...... ................................ .. ... ..................... 100

MODULE #5: The Hydrosphere ....................................................................................................... 105

Introduction ... ... ........................... .. .. .... .............. .... ..... ....................... ........................................... ..... 105 The Parts of the Hydrosphere and the Hydro logic Cycle .. ... ..... ....... ....................... ............. ............ . 107 Experiment 5 .1 :Evaporation, Condensation, and Precipitation ............ .... ....... ........... ... ..... ...... .... .... 109 The Ocean ........ ......... ..... ........ ..... ..... ......... ... ..... ...... ........ ..... .. ...... ........ ....... ... ........ .. ..... ...... ........... .... 113 Glaciers and Icebergs ................. ............ ...... .......... .......... ........ .................... ............... ........ .............. 116 Experiment 5.2: Ice and Salt ... ..... ........ ................... ...... ...... ..................................... ... .. .... .. ........ ...... 116 Groundwater and Soil Moisture .............................................................................. .... ...................... 120 Surface Water ...... .. ..................... ...... ....... .... ... ........ ..... .................. ... .............. ..................... ..... ..... .... 122 Atmospheric Moisture .............. .......... .......... ........... ... ... ... .............. ................... .. ... ... ... ........ ............. 122 Experiment 5.3: Cloud Formation .. ...... ..... ................. ......... ....................................... ........ .............. . 122 Water Pollution ... ....................... ....................... .. .... ... .... .. ......... ... ....... ..... ... ...... .... ... ......... ................ 126

MODULE #6: Earth and the Lithosphere ........................................................................................ 131

Introduction ........ ............... ........... .... ......... ............... ........ ............. ..... .............. ........... .... .......... ... ..... 131 The Crust ........... ................................... .. ................. ..... ......... ...... ..... ....... ...... ....... ............................. 132 The Mantle ............. .. ...... .. ......... ..... ......... ..... ..... .. ..... ................ ..... .... ..... ................... ...... ............. ... .. 13 3 Experiment 6.1: How Sound Travels Through Different Substances ............................. ..... .... ... ...... 133 Experiment 6.2: A Simulation of Plastic Rock ....... .......... ........................................ ........................ 136 The Earth's Core ...... ..... ... ... ......................... ................................ ...... ............ ............. .... .... .... .......... 138 Experiment 6.3: Making an Electromagnet. ...... .. .. ..... ... ........ .. .... ......... ...... .... ... .... ............................ 140 Plate Tectonics .... .......... ......... ............ ... ... ........................ ........ ............................... ......... .... .... ..... .... 144 Experiment 6.4: A Model of Plate Tectonics .... .... .. ........ ................ .................... .... ...... ... ........ ...... ... 145 Earthquakes ............ .. ...... ...... ...... .............. .... ........ .............. ... .. ....... ....... .......... ......... ......................... 148 Mountains and Volcanoes ....... ...... ..... ........... ......... ....... ... ...... ...................... ............. ..... ....... ....... .. ... 151

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MODULE #7: Factors That Affect Earth's Weather ...................................................................... 157

Introduction ....... ....... ..... ..... .... .... .. ... ...... .... ............ ...... ....... .... ...................... ........ .. .... ..... .... .............. 157 Factors That Influence Weather ....... .......... ........ ....... .. ... ....................................... .. ................... ... .. .. 157 Clouds ..... ........ .... .... ... ............... .... .... ............ .......... ..... ........... ....... ...... ........ ... .................. ..... ... .... ... .. 157 . Experiment 7 .1: A Long-Term Weather Experiment.. ... ...... ... ... ... ............. ..... ... ...... ....... .. ......... ...... . 160 Earth's Thermal Energy .... ..... .............. .... ..... .................................................................................... 161 Latitude and Longitude ....... ...... ................ ... ..... .... ..... .... ....... ..... ............. .... ... ..... ..... ............... .......... 165 Uneven Thermal Energy Distribution .... ... ........ ..... ........................................................................... 166 Air Masses ..... ..... ......... ....... .................. ...... .............. ....... .. ... .............. ........ ..... .. ..... ....... .... .. ... .......... . 172

MODULE #8: Weather and Its Prediction ...................................................................................... 181

Introduction ... ... .. ... .... ........................ .......... ............ ..... ................ ....... ................................... ........... 181 Precipitation .... ... ..... .................. ... .......... ...... ...... ........ ........ .. ............ ... ....... .................. ........... .. .. ..... . 181 Thunderstorms ........ .................. .. .. ......... ............. .......... ......... .. ....... ............ ....... ........... ................ ..... 183 Experiment 8.1: Making Your Own Lightning ..... ..... ......... ....... .. ... ........... ..... ............. ... ..... ............. 186 Tornadoes and Hurricanes ... ................... ...................................... ... .... .. ..... ........ ... .. ...... ... ... ...... .. ...... 190 Weather Maps and Weather Prediction ..... ........... .... ..... .. ......................... ............. ...... .... ....... ..... .. .... 194 Interpreting the Results of Experiment 7.1 and Making Your Own Weather Predictions .......... .... .. 198 Experiment 8.2: Turning Experiment 7.1 into a Weather Prediction Tool ...... .... .................. .. ... ...... 199

MODULE #9: An Introduction to the Physics of Motion ............................................................... 203

Introduction ....................................................................................................................................... 203 Mechanics - The Study of Motion, Forces, and Energy ....................................................... ............ 203 Speed: How Quickly Motion Occurs ....... ................. .... ................................ ....... ............ ................ 206 Velocity: Speed and Direction ................... .... .......... ......................................................................... 208 Experiment 9 .1: The Importance of Direction ................. .. ....... ............. ...... ........... ..... ......... .. .......... 209 Acceleration: The Rate of Change in Velocity ................................................................................. 212 The Acceleration Due to Gravity ................ ... ........ ... .... ........ .... .. .... .... .... .. ............ ...... ......... ........ ..... 218 Experiment 9.2: The Acceleration Due to Gravity is Independent of the Object Falling ................. 219 Experiment 9.3: Measuring Height With a Stopwatch ... .... .... .... .... .. ... ........ ...... ... .... ........ .... .. .......... 221

MODULE #10: Newton's Laws ......................................................................................................... 229

Introduction ... ...... ..... ................................... ... ................................................................................... 229 Sir Isaac Newton ............ ... .............. .. ............ ........ ....... ............ ................... ........ ......... ..... ................ 229 Newton's First Law of Motion ................................. ..... ................... ................ ................................. 230 Experiment 10.1: Two Experiments Demonstrating Newton's First Law ............ ....... ................... .. 231 Experiment 10.2: An Experiment to See How Well You Understand Newton's First Law .. ...... ..... 235 Friction ..... ......................... ... ........ .......... ..... .............. ... ... ..... ..... ...... ................. .... ...... .... .. ........ .... ..... 23 7 Experiment 10.3: Friction ........ ............ ...... ... ........ ............................................................................ 237 Newton's Second Law of Motion ..... .. ... ... ........ ............. .... ... ...... .. ........ .... ..... ... ..... .. ...... .. ................. 240 Static and Kinetic Friction .................................................................................. .... ...... ............. .. ... ... 244 Newton's Third Law of Motion ................. ................ ....... .. .............. ...... ............ .............................. 246 Experiment 10.4: Newton's Third Law ............ ............. .................. .. ... .. ... ....... ................ .. .... .... ....... 247

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MODULE #11: The Forces in Creation - Part 1 .............................................................................. 255

Introduction .............. .... ............................... ..... .......... ............. ... ....................................................... 255 The Four Fundamental Forces of Creation ....................................................................................... 255 The Gravitational Force .................................................................................................................... 255 Force and Circular Motion .............................. .... ........................................... ....... .................. ...... .. .. 260 Experiment 11.1: Force and Circular Motion ........... .... .................................................................... 260 A Fictional Force ...................................................... ..... .............................. ......... ... ........................ .. 263 The Gravitational Force at Work in Our Solar System ............ ........ ................ .......... ....................... 265 Comets ............ ....... .................................. ......... .... ........... ... ... ......... ..................................... .............. 269 Hey, What About Pluto? .... .............. ... ............ .................................................................................. 272 What Causes the Gravitational Force? ......... ....... ..... ................................. ...... .................................. 274 Experiment 11.2: The "Bent Space and Time" Theory of Gravity ............. .......... ............................ 274 Experiment 11.3: The Graviton Theory of Gravity ........................................................................... 276 A Brief History of Our View of the Solar System ............................................................................ 278

MODULE #12: The Forces in Creation - Part 2 .............................................................................. 285

Introduction ..... .................... ....................... .... .. ... .............................................................................. 285 James Clerk Maxwell .............................................. ................................ ...... .................................... 285 The Electromagnetic Force ....... ..... ...................................................... .. ............. .... .......................... 286 Experiment 12.1: Electrical Attraction and Repulsion ... ........................................... ........ ................ 286 Photons and the Electromagnetic Force ...... ............. .... .......................................... .......... ............ ... .. 290 How Objects Become Electrically Charged .................... ......................... ..... ..... ............. ............... ... 291 Experiment 12.2: Making and Using an Electroscope ........................................... .......... ................. 291 Electrical Circuits ....... ............... ....... .......................................... .. ........................ .... ......................... 295 Resistance ..................... .. ... ... ... ................................... .................... ... ......... ... ....... .... ................ ......... 299 Experiment 12.3: Current and Resistance ......... .......... ............................................ .......... ........ ........ 299 Switches and Circuits ........ ..................................... ........................................................................... 302 Series and Parallel Circuits ......... ..... ........................................ ............................ ...... ....................... 303 Magnetism .............................................................................. ...... ..................................................... 305 Permanent Magnets ........................................................................................................ ... ................ 306

MODULE #13: The Forces in Creation - Part 3 .............................................................................. 313

Introduction .......................................................................................................................... ............. 313 The Structure of the Atom ............................. .. ............................................................ .... .................. 313 The Periodic Table of the Elements ..................................... ... ...................... ......... .................... ... ...... 320 The Strong Force .......... ... ........................................................... ... ..................................................... 325 Radioactivity ............................ .......... ..................................................................................... .. ........ 327 The Dangers of Radioactivity ........... ...... ............... ........ .......................................... .......... ....... ........ .. 330 The Rate of Radioactive Decay .......................................................................................................... 332 Radioactive Dating .................................. ....................... ... ..... ....... ....................... .......... ................... 334

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MODULE #14: Waves and Sound .................................................................................................... 341

Introduction ............... ..... ..................................... ... .................................... ... ............ .... ......... ....... .... 341 Waves .............. ..... ................... ...... .. .. ..... ... ..................... ............. ........ .............................................. 341 . Sound vVaves ..................................................................................................................................... 344 Experiment 14.1: The Medium Through Which Sound Waves Travel ............................................ 344 The Speed of Sound ............... ..... ....... .... ..... ...................................................................................... 347 Experiment 14.2: The Speed of Sound .......... .. .......... ... ...................................... ............................... 347 The Speed of Sound in Other Substances ............. ............................. .... ..... .......... .. ............. ... .......... 351 Sound Wavelength and Frequency ................................. ..... .............................................................. 353 Experiment 14.3: Wavelength and Sound ...................................................................................... ... 353 The Doppler Effect ......... ..... ....................... .. ...... .... ...................... ............... ... ...... ....................... ... ... 355 Experiment 14.4: The Doppler Effect ............................................................................................... 356 The Volume of Sound .............................. ..... ... .................. ............................................................... 357 Experiment 14.5: The Amplitude ofa Sound Wave ........ ....... .......................................................... 358 Uses of Sound Waves ... ......................................... .......... ............... ........ ...... .... .................... ......... ... . 361

MODULE #15: Light ... .......................................... ............................................................................. 367

Introduction ... ...... ......... ... ...................................... ..... ......... ..... ...................................... ............. ...... 367 The Dual Nature of Light ................................................................... ..... ....................... ... ......... ....... 367 Wavelength and Frequency of Light ................... ...................................................... ........................ 370 Experiment 15 .1: Seeing Different Wavelengths of Light. .................... ........ ..... .............................. 3 70 Reflection ............................. ... ......... ..... ............................ ... ... .......................... ............................... . 3 7 4 Experiment 15.2: The Law of Reflection ....................... .. ............. .................... ..... ....... .... ............... . ~74 Refraction ................................ .. .............. ... .......................... ............................................................. 377 Experiment 15.3: Refraction of Light ....... .... ........................ ..................... ....................................... 378 Experiment 15.4: The "Magical" Quarter ........... ......... ........ .................................................... ......... 380 Lenses ................................................ .... .................................... .... ........... ..... .................................... 383 The Human Eye .... .... ............................................ ..... .. .. ......................... .......... ........ ......................... 385 How We Perceive Color ..................... ..... ............................ ... ........................................................... 388 Experiment 15.5: How the Eye Detects Color ..... .......... ............ ................... ............. ....... ................ 388 Adding and Subtracting Colors ...................................... .... ......... ........... ..... ......... ...... ... .................... 389

MODULE #16: An Introduction to Astrophysics ............................................................................ 397

Introduction ....................... ................. ...... .......... .............................................................................. . 397 The Sun .............................. ........ ...... ....... ... ...................................................................... ...... ...... ...... 397 Nuclear Energy ................................................................... .......... ..................................................... 401 Classifying the Stars in the Universe ................. .... ...... ................ .. ... ........ ..... .......... ... ............... .... .. . 404 Variable Stars ....... ..... ..... ... ........................ ................. ... ............................. ... ............ ........ ................ 409 Measuring the Distance to Stars ... ........ ............. .................................................................. ............ .. 411 Galaxies ....................... ..... ................ .... .................. ... ...... ..... ............................................................. 413 An Expanding Universe .................................................................................................................... 414 Experiment 16.1: An Expanding Universe .............................................................................. .. ....... 416 Summing It All Up ............. .................................. .... ................... .... ........ ... ....................................... 418

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Glossary ............................................................................................................................................... 423

Appendix A .......................................................................................................................................... 433

Appendix B .......................................................................................................................................... 449

Appendix C .......................................................................................................................................... 481

lndex ..................................................................................................................................................... 489

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MODULE #1: The Basics

Introduction

In this course, you are going to learn a lot about the world around you and the universe it is in . We will study things as familiar as the air around you and others as mysterious as radioactivity and distant galaxies. We will learn about the structure of the earth as well as its place in the solar system and the universe . The study of these topics and many others like them are all a part of what we call physical science.

In order to make sure we are both starting on the "same page," I need to discuss some basic concepts with you. It is quite possible that you have learned some ( or all) of this before, but it is necessary that we cover the basics before we try to do anything in depth. Thus, even if some of the topics I cover sound familiar, please read this module thoroughly so that you will not get lost in a later module. In fact, many of the subjects I will cover in later modules are probably familiar to you on one level or another. After all, most students your age know something about air, the construction of our planet, weather, and astronomy. Nevertheless, I can almost guarantee that you have not learned these subj ects at the depth in which I will discuss them in this course. So, despite how much you might think you know about a given topic, please read the material I present to you carefully. I doubt that you will be disappointed.

If, on the other hand, all this is completely new to you, don ' t worry about it. As long as you read the material carefully, perform the experiments thoroughly, and really think about what you are learning, everything will be fine. Although this course might not be easy for you, there are very few things in life that are both easy and worthwhile. I promise that if you work at learning this course, you will gain a great deal of knowledge, a solid sense of accomplishment, and a grand appreciation for the wonder of God's creation!

Atoms and Molecules

In this course, I am going to illustrate as many concepts as possible with experiments. Hopefully, the "hands on" experience will help bring those concepts home better than any discussion could. In some cases, of course, this will not be possible, so we will have to make do with words and pictures. To start our discussion of atoms and molecules, I want you to perform the following experiment:

EXPERIMENT 1.1 Atoms and Molecules

Supplies: ♦ A small, clear glass (like a juice glass) ♦ Baking soda ♦ Tap water ♦ A 9-volt battery (the kind that goes in a radio, smoke detector, or toy. DO NOT use an electrical

outlet, as that would be quite dangerous! A 1.5-volt flashlight battery will not work.) ♦ Two 9-inch pieces of insulated wire. The wire itself must be copper. ♦ Scissors ♦ Some tape (preferably electrical tape, but cellophane or masking tape will work.) ♦ A spoon for stirring ♦ Eye protection such as goggles or safety glasses

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4 Exploring Creation With Physical Science

building blocks in creation, He designed those atoms to link together to form larger building blocks called molecules.

Molecule - Two or more atoms linked together to make a substance with unique properties

It turns out that the water you used in your experiment is made up of molecules. Although molecules are bigger than atoms, you still cannot really see them. Thus, the water you see is made up of billions and billions and billions of water molecules, just like the copper wire is made up of billions and billions and billions of atoms of copper. A water molecule is formed when an oxygen atom links together with two hydrogen atoms. When these atoms link together in a very specific way, the result is a water molecule. The difference between atoms and molecules is illustrated below.

Atoms FIGURE 1.1

Atoms and Molecules

Illustration by Megan Whitaker

Molecules

A bunch of oxygen atoms (red) and hydrogen atoms (yellow) grouped together. This is a mixture of two different substances, each with its own properties.

The same oxygen and hydrogen atoms linked together to make water molecules. They all have the same properties, which are quite different from the properties of oxygen and hydrogen atoms.

Now we are ready to really discuss the results of the experiment. When you filled the glass with water, you were filling it with billions and billions and billions of water molecules . When you placed the wires (which were connected to the battery) into the water, the electricity from the battery began flowing through the water. When this happened, the energy from the electricity flow actually broke some of the water molecules down into hydrogen and oxygen, which began bubbling out of the water, because hydrogen and oxygen are gases!

This tells us something about molecules. Each water molecule is made up of two hydrogen atoms and an oxygen atom linked together. When these atoms link together in that way, an odorless, colorless, tasteless liquid we call water is formed. When electricity is used to break the water molecules down, hydrogen and oxygen are formed. Hydrogen is an explosive gas, while oxygen is the gas we breathe to stay alive. Think about that. Oxygen and hydrogen are each gases with particular properties. When the atoms that make them up link together so that two hydrogen atoms are linked to one oxygen atom, however, these individual properties are lost, and a new substance (water) with new properties ( odorless, colorless, tasteless liquid) is formed.

In one part of the experiment, then, you saw a molecule (water) breaking down into two gases made up of its two constituent atoms (hydrogen gas and oxygen gas). Well, when you pulled the wires

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Module 1 The Basics

out of the water after 10 minutes, you saw that the wire connected to the positive terminal of the battery had turned a bluish-green color. In this case, the copper atoms in the wire interacted with water molecules and baking soda molecules, aided by the energy contained in the electricity. The result was a bluish-green substance called copper hydroxycarbonate (hi drok' see car' buh nate ). Copper hydroxycarbonate is formed when a copper atom links together with oxygen atoms, carbon atoms, and " hydrogen atoms. In this experiment, the hydrogen and oxygen atoms came from both the water and the baking soda, the carbon atoms came from the baking soda alone, and the copper atoms came from the wire. In this case, then, you observed atoms (copper) linking up with other atoms (oxygen, carbon, and hydrogen) to make a molecule ( copper hydroxycarbonate ).

Interestingly enough, copper hydroxycarbonate is the same substance that you see on many statues, such as the Statue of Liberty. You see, if a structure made of copper (like the Statue of Liberty) is exposed to weather, a process similar to the one you observed turns the copper atoms in the statue into copper hydroxycarbonate. As a result, the structure turns bluish-green, just like one of the copper wires did in your experiment.

FIGURE 1.2 The Statue of Liberty and a Civil War Cannon

Photos © Daniel Slocum (left) and Geoffrey Kuchera (right) Agency: Dreamstime.com

The Statue of Liberty (left) turned bluish-green because hydrogen, oxygen, and carbon atoms from various substances in the air have combined with copper atoms to make copper hydroxycarbonate. This Civil War cannon (right) is made of bronze, which is a mixture of copper and tin. The copper in the mixture has also reacted to form copper hydroxrcarbonate.

Chemical reactions like the ones you observed in your experiment are how we get all the incredible substances you see around you. Some substances (copper, aluminum, and some others) are made of billions and billions and billions of the same atom. These substances are often called elements. Other substances we see (water, salt, sugar, and many others) are made up of billions and billions and billions of molecules. They are often called compounds. Finally, many substances we

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