Chemistry For Dummies,® 2nd Edition
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Library of Congress Control Number: 2011926326
ISBN: 978-1-119-29346-0 (pbk); ISBN: 978-1-119-29727-7 (ebk); ISBN: 978-1-119-29728-4 (ebk)
Chemistry For Dummies, 2nd Edition (9781119293460) was previously published as Chemistry For Dummies, 2nd Edition (9781118007303). While this version features a new Dummies cover and design, the content is the same as the prior release and should not be considered a new or updated product.
You’ve passed the first hurdle in understanding a little about chemistry: You’ve picked up Chemistry For Dummies, 2nd Edition. I imagine that a large number of people looked at the title, saw the word chemistry, and bypassed it like it was covered in germs.
I don’t know how many times I’ve been on vacation, struck up a conversation with someone, and been asked the dreaded question: “What do you do?”
“I’m a teacher,” I reply.
“Really? And what do you teach?”
I steel myself, grit my teeth, and say in my most pleasant voice, “Chemistry.”
I see The Expression, followed by, “Oh, I never took chemistry. It was too hard.” Or “You must be smart to teach chemistry.” Or “Goodbye!” If I were still in the dating scene, “Hi, I teach chemistry” would not be a good pick-up line!
I think a lot of people feel this way because they think that chemistry is too abstract, too mathematical, too removed from their real lives. But in one way or another, all of us do chemistry.
Remember making that baking soda and vinegar volcano as a child? That’s chemistry. Do you cook or clean or use fingernail polish remover? All that is chemistry. I never had a chemistry set as a child, but I always loved science. My high school chemistry teacher was a great biology teacher but really didn’t know much chemistry. But when I took my first chemistry course in college, the labs hooked me. I enjoyed seeing the colors of the solids coming out of solutions. I enjoyed synthesis, making new compounds. The idea of making something nobody else had ever made before fascinated me. I wanted to work for a chemical company, doing research, but then I discovered my second love: teaching.
Chemistry is sometimes called the central science (mostly by chemists), because in order to have a good understanding of biology or geology or even physics, you must have a good understanding of chemistry. Ours is a chemical world, and I hope that you enjoy discovering the chemical nature of it — and that afterward, you won’t find the word chemistry so frightening.
My goal with this book is not to make you into a chemistry major. My goal is simply to give you a basic understanding of some chemical topics that commonly appear in high school or college introductory chemistry courses. If you’re taking a course, use this book as a reference in conjunction with your notes and textbook.
Simply watching people play tennis, no matter how intently you watch them, will not make you a tennis star. You need to practice. And the same is true with chemistry. It’s not a spectator sport. If you’re taking a chemistry course, then you need to practice and work on problems. I show you how to work certain types of problems — gas laws, for example — but use your textbook for practice problems. It’s work, yes, but it really can be fun.
As I updated this second edition of Chemistry For Dummies, I reflected on what to include. I’ve enjoyed getting e-mails from people all over the world asking questions about the first edition or thanking me. However, looking at the overall feedback, I felt that I hadn’t included quite enough about calculations and some other topics that students taking a college or high school–level class really needed. So in this second edition I beefed up the calculations and included some extra topics normally found in the first year of high school chemistry or the first semester of general chemistry in college. Overall, this edition will be more useful to those of you taking the chemistry course. For those of you who want some help with second-semester topics, hang in there and maybe, just maybe, you’ll soon see Chemistry II For Dummies in your local bookstore.
I really don’t know why you bought this book (or will buy it — in fact, if you’re still in the bookstore and haven’t bought it yet, buy two and give one as a gift), but I assume that you’re taking (or retaking) a chemistry course or preparing to take a chemistry course. I also assume that you feel relatively comfortable with arithmetic and know enough algebra to solve for a single unknown in an equation. And I assume that you have a scientific calculator capable of doing exponents and logarithms.
And if you’re buying this book just for the thrill of finding out about something different — with no plan of ever taking a chemistry course — I applaud you and hope that you enjoy this adventure. Feel free to skip those topics that don’t hold your interest; for you, there will be no tests, only the thrill of increasing your knowledge about something new.
I know you’re a busy person and want to get just what you need from this book. Although I want you to read every single word I’ve written, I understand you may be on a time crunch. I keep the material to the bare bones, but I include a few sidebars. They’re interesting reading (again, at least to me) but not really necessary for understanding the topic at hand, so feel free to skip them. This is your book; use it any way you want.
I mark some paragraphs with Technical Stuff icons. What I tell you in these paragraphs is more than you need to know, strictly speaking, but it may give you helpful or interesting detail about the topic at hand. If you want just the facts, you can skip these paragraphs.
I present this book’s content in a logical progression of topics. But this doesn’t mean you have to start at the beginning and read to the end of the book. Each chapter is self-contained, so feel free to skip around. Sometimes, though, you’ll get a better understanding if you do a quick scan of a background section as you’re reading. To help you find appropriate background sections, I’ve placed “see Chapter X for more information” cross-references here and there throughout the book.
Because I’m a firm believer in concrete examples, I also include lots of illustrations and figures with the text. They really help in the understanding of chemistry topics. And to help you with the math, I break up problems into steps so that you can easily follow exactly what I’m doing.
I’ve organized the topics in a logical progression — basically the same way I organize my courses for science and non-science majors. Following is an overview of each part of the book.
In this part, I introduce you to the really basic concepts of chemistry. I define chemistry and show you where it fits among the other sciences (in the center, naturally). I show you the chemical world around you and explain why chemistry should be important to you. I also have a chapter (Chapter 2) devoted to chemical calculations. I show you how to use the factor label method of calculations, along with an introduction to the SI (metric) system. I also show you the three states of matter and talk about going from one state to another — and the energy changes that occur.
Besides covering the macroscopic world of things like melting ice, I cover the microscopic world of atoms. I explain the particles that make up the atom — protons, neutrons, and electrons — and show you where they’re located in the atom.
I discuss how to use the periodic table, an indispensable tool for chemists. And I introduce you to the atomic nucleus, including the different subatomic particles. Finally, I introduce you to the wonderful world of gases. In fact, in the gas chapter, you can see so many gas laws (Boyle’s law, Charles’s law, Gay-Lussac’s law, the combined gas law, the ideal gas law, Avogadro’s law, and more) that you may feel like a lawyer when you’re done. The material in these chapters gets you ready for additional topics in chemistry.
In this part, you get into some really good stuff: chemical reactions. I give some examples of the different kinds of chemical reactions you may encounter and show you how to balance them. (You really didn’t think I could resist that, did you?) I also introduce the mole concept. Odd name, yes, but the mole is central to your understanding of chemical calculations. It enables you to figure the amount of reactants needed in chemical reactions and the amount of product formed. I also talk about solutions and how to calculate their concentrations. And I explain why I leave the antifreeze in my radiator during the summer and why I add rock salt to the ice when I’m making ice cream.
This part gets into thermochemistry. Energy changes take place during chemical reactions. Some reactions give off energy (mostly in the form of heat), and some absorb energy in the form of heat. I show you how to figure how much heat is released. It may be enough to make you break out in a sweat. Finally, I tell you about acids and bases, things sour and things bitter. I discuss how to calculate their concentration and the pH of a solution.
I start off in this part talking about quantum theory, through which an electron can be represented by the properties of both particles and waves. In the first chapter, I throw certainties out the window and introduce you to probabilities. Then I explain bonding. I show you how table salt is made in Chapter 13, which covers ionic bonding, and I show you the covalent bonding of water in Chapter 14. I explain how to name some ionic compounds and how to draw Lewis structural formulas of some covalent ones. I even show you what some of the molecules look like. (Rest assured that I define all these techno-buzzwords on the spot, too.)
I also talk about periodic trends of the elements and intermolecular forces, those extremely important forces that give water its most unusual properties.
In this part, I discuss some environmental issues, specifically air and water pollution. I demonstrate what causes those pollutants and what chemistry can do to correct those problems. These issues, which are so often in the news, are among the most important problems society faces, and in order to evaluate possible solutions, you must have a little knowledge of chemistry. I hope that you don’t get lost in the smog!
Finally, I introduce you to nuclear chemistry, with discussions about radioactivity, carbon-14 dating, fission, and fusion nuclear reactors.
In this part, I introduce you to ten great serendipitous chemical discoveries, ten great chemistry nerds (nerds rule!), and ten useful tips for passing Chem I. I started to put in my ten favorite chemistry songs, but I could only think of nine. Bummer. I also include a chapter on ten common chemicals used today to help you understand how basic chemistry affects daily life.
If you’ve read other For Dummies books, you’ll recognize the icons used in this book, but here’s the quickie lowdown for those of you who aren’t familiar with them:
This icon gives you a tip on the quickest, easiest way to perform a task or conquer a concept. This icon highlights stuff that’s good to know and stuff that’ll save you time and/or frustration.
The Remember icon is a memory jog for those really important things you shouldn’t forget.
I use this icon when safety in doing a particular activity, especially mixing chemicals, is described.
This icon points out different example problems you may encounter with the respective topic. I walk you through them step by step to help you gain confidence.
I don’t use this icon very often because I keep the content pretty basic. But in those cases where I expand on a topic beyond the basics, I warn you with this icon. You can safely skip this material, but you may want to look at it if you’re interested in a more in-depth description.
Where to go from here is really up to you and your prior knowledge. If you’re trying to clarify something specific, go right to that chapter and section. If you’re a real novice, start with Chapter 1 and go from there. If you know a little chemistry, I suggest quickly reviewing Part 1 and then going on to Part 2. Chapter 8 on the mole is essential, and so is Chapter 6 on gases.
If you’re most interested in environmental chemistry, go on to Chapters 18 and 19. You really can’t go wrong. I hope that you enjoy your chemistry trip.
Part 1
IN THIS PART …
If you are new to chemistry, it may seem a little frightening. I see students every day who’ve psyched themselves out by saying so often that they can’t do chemistry. The good news: Anyone can figure out chemistry. Anyone can do chemistry. If you cook, clean, or simply exist, you’re part of the chemical world.
I work with a lot of elementary school children, and they love science. I show them chemical reactions (vinegar plus baking soda, for example), and they go wild. And that’s what I hope happens to you when you read this book and find out how interesting and important chemistry can be.
The chapters of Part 1 give you a background in chemistry basics. I show you how to do calculations and introduce you to the metric system. I tell you about matter and the states it can exist in, and I also talk a little about energy, including the different types and how it’s measured. I discuss the microscopic world of the atom and its basic parts and explain how information about atoms is conveyed in the periodic table, the most useful tool for a chemist. And I cover the world of gases. This part takes you on a fun ride, so get your motor running!
Chapter 1
IN THIS CHAPTER
Defining the science of chemistry
Finding out about science and technology
Working out the scientific method
Checking out the general areas of chemistry
Discovering what to expect in a chemistry class
If you’re taking a course in chemistry, you may want to skip this chapter and go right to the area you’re having trouble with. You already know what chemistry is — it’s a course you have to pass. But if you bought this book to help you decide whether to take a course in chemistry or to have fun discovering something new, I encourage you to read this chapter. I set the stage for the rest of the book here by showing you what chemistry is, what chemists do, and why you should be interested in chemistry.
I really enjoy chemistry. It’s far more than a simple collection of facts and a body of knowledge. I was a physics major when I entered college, but I was hooked when I took my first chemistry course. It seemed so interesting, so logical. I think it’s fascinating to watch chemical changes take place, to figure out unknowns, to use instruments, to extend my senses, and to make predictions and figure out why they were right or wrong. The whole field of chemistry starts here — with the basics — so consider this chapter your jumping-off point. Welcome to the interesting world of chemistry.
This whole branch of science is all about matter, which is anything that has mass and occupies space. Chemistry is the study of the composition and properties of matter and the changes it undergoes, including energy changes.
Science used to be divided into very clearly defined areas: If it was alive, it was biology. If it was a rock, it was geology. If it smelled, it was chemistry. If it didn’t work, it was physics. In today’s world, however, those clear divisions are no longer present. You can find biochemists, chemical physicists, geochemists, and so on. But chemistry still focuses on matter and energy and their changes.
A lot of chemistry comes into play with that last part — the changes matter undergoes. Matter is made up of either pure substances or mixtures of pure substances. The change from one substance into another is what chemists call a chemical change, or chemical reaction, and it’s a big deal because when it occurs, a brand-new substance is created (see Chapter 3 for the nitty-gritty details).
So what are compounds and elements? Just more of the anatomy of matter. Matter is pure substances or mixtures of pure substances, and substances themselves are made up of either elements or compounds. (Chapter 3 dissects the anatomy of matter. And, as with all matters of dissection, it’s best to be prepared — with a nose plug and an empty stomach.)
Science is far more than a collection of facts, figures, graphs, and tables. Science is a method for examining the physical universe. It’s a way of asking and answering questions. However, in order for it to be called science, it must be testable. Being testable is what makes science different from faith.
For example, you may believe in UFOs, but can you test for their existence? How about matters of love? Does she love me? How much does she love me? Can I design a test to test and quantify that love? I think not. I have to accept that love on faith. It’s not based in science, which is okay. Mankind has struggled with many great questions that science can’t answer. Science is a tool that is useful in examining certain questions, but not all. You wouldn’t use a front-end loader to eat a piece of pie, nor would you dig a ditch with a fork. Those are inappropriate tools for the task, just as science is an inappropriate tool for areas of faith.
Science is best described by the attitudes of scientists themselves: They’re skeptical. They simply won’t take another person’s word for a phenomena — it must be testable. And they hold onto the results of their experiments tentatively, waiting for another scientist to disprove them. Scientists wonder, they question, they strive to find out why, and they experiment — they have exactly the same attitudes that most small children have before they grow up. Maybe this is a good definition of scientists — they are adults who’ve never lost that wonder of nature and the desire to know.
Technology, the use of knowledge toward a very specific goal, actually developed before science. Ancient peoples cooked food, smelted ores, made beer and wine by fermentation, and made drugs and dyes from plant material. Technology initially existed without much science. There were few theories and few true experiments. Reasoning was left to the philosophers. Eventually alchemy arose and gave chemistry its experimental basis. Alchemists searched for ways to turn other metals into gold and, in doing so, discovered many new chemical substances and processes, such as distillation. However, it wasn’t until the 17th century that experimentation replaced serendipity (see the next section for a discussion of serendipity) and true science began.
The scientific method is normally described as the way scientists go about examining the physical world around them. In fact, no one uses just one scientific method every time, but the one I cover here describes most of the critical steps scientists go through sooner or later. Figure 1-1 shows the different steps in the scientific method.
FIGURE 1-1: The scientific method.
The following sections examine more in-depth what the scientific method is and how you can use it in all your studies, not just chemistry.
The way scientists are supposed to do their jobs is through the scientific method: a circular process that goes from observations to hypotheses to experiments and back to observations. These steps may lead in some cases to the creation of laws or theories.
To begin the scientific method, scientists make observations and note facts regarding something in the physical universe. The observations may raise a question or problem that the researcher wants to solve. He or she comes up with a hypothesis, a tentative explanation that’s consistent with the observations (in other words, an educated guess). The researcher then designs an experiment to test the hypothesis. This experiment generates observations or facts that can then be used to generate another hypothesis or modify the current one. Then more experiments are designed, and the loop continues.
In good science, this loop of observations, hypothesis, and experimentation never ends. As scientists become more sophisticated in their scientific skills, think of better ways of examining nature, and build better and better instruments, their hypotheses are tested over and over. Conclusions that may appear to be scientifically sound today may be modified or even refuted tomorrow.
Besides continuing the loop, good experiments done with the scientific method may lead the researcher to propose a law or theory. A law is simply a generalization of what happens in the scientific system being studied. For example, the law of conservation of matter stated that matter is neither created nor destroyed. And like the laws that have been created for the judicial system, scientific laws sometimes have to be modified based on new facts. With the dawn of the nuclear age, scientists realized that in nuclear reactions a small amount of matter disappears and is converted to energy. So the law of conservation of matter was changed to read: In ordinary chemical reactions, matter is neither created nor destroyed.
A theory or model may also be proposed. A theory or model attempts to explain why something happens. It’s similar to a hypothesis except that it has much more evidence to support it. What separates a theory from an opinion is that it has numerous experiments, many observations, and lots of data — in a nutshell, facts — supporting it.
The power of the theory or model is prediction. If the scientist can use the model to gain a good understanding of the system, then he or she can make predictions based on the model and then check them out with more experimentation. The observations from this experimentation can be used to refine or modify the theory or model, thus establishing another loop in the process. When does it end? Never. Again, as mankind develops more advanced instrumentation and ways of examining nature, scientists may find it necessary to modify our theories or models.
Many scientific discoveries are made through the scientific method. However, many discoveries are made by another process, called serendipity. Serendipity is an accidental discovery. The discoveries of penicillin, sticky notes, Velcro, radioactivity, Viagra, and so on were made by accident. But recognizing an accidental discovery takes a well-trained, disciplined, scientific mind. See Chapter 21 for a list of what I consider to be ten important serendipitous discoveries in chemistry.
Most people use the scientific method in their everyday lives without even thinking about it. You just think of it as tackling a problem logically. For example, suppose you buy that new HD TV and home theater system you’ve been wanting. You even buy a new CD changer so that you can listen to hours of music while studying. After unpacking and hooking everything up, you notice that you have no sound coming out of the left speakers when a CD is playing. You’ve identified a problem to investigate. Now you need to apply the scientific method to solve the problem. Here are some general steps to use:
Develop a hypothesis about what you’re studying.
This hypothesis is an educated guess you make about what you think the end results will be. A hypothesis gives you an idea of what to expect, although after you conduct your experiments, you may determine the hypothesis is invalid.
For example, in the case of the dead left speakers, you may think that the problem lies with the CD changer, the receiver, or the cables connecting the two because everything else is working correctly. You form the hypothesis that something is wrong with the CD cables, that perhaps the left wire is broken or its connection is bad. You decide to experiment.
Conduct your experiment.
Carefully design this experiment, with as many variables as possible being controlled. Variables are factors that can affect the outcome of the experiment. In chemistry, variables may be temperature, pressure, volume, and so on. (Controlling all the variables is very difficult when human beings are involved, which is why social-science experiments are so difficult.) In this example, the connections at both the CD player and the receiver are variables as well as the cable between the connections. You would only want to change one thing at a time. The simplest thing to do is to switch how the cable is connected at the CD unit. Just switch the right cable lead with the left one and vice versa. Suppose the left speakers are playing but the right set is dead. What does that tell you?
Use the data and information from the experiment to generate a new hypothesis or modify the old one.
Because the opposite speakers began malfunctioning when the CD cable connections were swapped, either the CD changer or the cable must be faulty, not the receiver. So you conduct another experiment, using a new set of cables. Thank goodness, everything is now playing just fine.
You may argue that the procedure you used was just common sense, but it really was the scientific method. In fact, I really do think of the scientific method as just good common sense.
The general field of chemistry is so huge that it was originally subdivided into a number of different areas of specialization. But the different areas of chemistry now have a tremendous amount of overlap, just as there is among the various sciences. Here are the traditional fields of chemistry:
Chemists, no matter what the type, all tend to examine the world around them in two ways — a macroscopic view and a microscopic view. The next sections take a look at these two viewpoints.
Most chemists that I know operate quite comfortably in two worlds. One is the macroscopic world that you and I see, feel, and touch. It’s the world of stained lab coats — of weighing out things like sodium chloride to create things like hydrogen gas. The macroscopic realm is the world of experiments, or what some nonscientists call the “real world.”
But chemists also operate quite comfortably in the microscopic world that you and I can’t directly see, feel, or touch. Here, chemists work with theories and models. They may measure the volume and pressure of a gas in the macroscopic world, but they have to mentally translate the measurements into how close the gas particles are in the microscopic world.
Scientists often become so accustomed to slipping back and forth between these two worlds that they do so without even realizing it. An occurrence or observation in the macroscopic world generates an idea related to the microscopic world, and vice versa. You may find this flow of ideas disconcerting at first. But as you study chemistry, you’ll soon adjust so that it becomes second nature.
In pure chemistry, chemists are free to carry out whatever research interests them — or whatever research they can get funded. They don’t necessarily expect to find a practical application for their research at this point. The researchers simply want to know for the sake of knowledge. This type of research (often called basic research) is
In applied chemistry, chemists normally work for private corporations. Theirresearch is directed toward a very specific short-term goal set by the company — product improvement or the development of a disease-resistant strain of corn, for example. Normally, more money is available for equipment and instrumentation with applied chemistry, but the chemists also have the pressure of meeting the company’s goals.
These two types of chemistry, pure and applied, share the same basic differences as science and technology. In science, the goal is simply the basic acquisition of knowledge without any need for apparent practical application. Science is simply knowledge for knowledge’s sake. Technology is the application of science toward a very specific goal.
Our society has a place for science and technology — likewise for the two types of chemistry. The pure chemist generates data and information that is then used by the applied chemist. Both types of chemists have their own sets of strengths, problems, and pressures. In fact, because of the dwindling federal research dollars, many universities are becoming much more involved in gaining patents, and they’re being paid for technology transfers into the private sector.