Textbook - Physics and Chemistry Science PDF

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ISBN-13: 978-0-03-099443-2 ISBN-10: 0-03-099443-8 1 2 3 4 5 6 7 082 11 10 09 08 07 Contents CHAPTER 1 The World of Physical Science SECTION 1 Exploring Physical Science................. 1 SECTION 2 Scientific Methods........................ 7 SECTION 3 Scientific Models........................ 15 SECTION 4 Tools, Measurement, and Safety........... 19 CHAPTER 2 The Properties of Matter SECTION 1 What Is Matter?......................... 23 SECTION 2 Physical Properties....................... 29 SECTION 3 Chemical Properties..................... 35 CHAPTER 3 States of Matter SECTION 1 Three States of Matter.................... 41 SECTION 2 Behavior of Gases....................... 45 SECTION 3 Changes of State........................ 49 CHAPTER 4 Elements, Compounds, and Mixtures SECTION 1 Elements.............................. 55 SECTION 2 Compounds............................ 59 SECTION 3 Mixtures............................... 63 Copyright © by Holt, Rinehart and Winston. 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Interactive Textbook iii Contents CHAPTER 5 Matter in Motion SECTION 1 Measuring Motion....................... 71 SECTION 2 What Is a Force?........................ 77 SECTION 3 Friction: A Force That Opposes Motion...... 81 SECTION 4 Gravity: A Force of Attraction.............. 85 CHAPTER 6 Forces and Motion SECTION 1 Gravity and Motion...................... 91 SECTION 2 Newton’s Laws of Motion................. 99 SECTION 3 Momentum........................... 107 CHAPTER 7 Forces in Fluids SECTION 1 Fluids and Pressure..................... 111 SECTION 2 Buoyant Force......................... 117 SECTION 3 Fluids and Motion...................... 123 CHAPTER 8 Work and Machines SECTION 1 Work and Power....................... 129 SECTION 2 What Is a Machine?..................... 135 SECTION 3 Types of Machines...................... 141 CHAPTER 9 Energy and Energy Resources SECTION 1 What Is Energy?........................ 149 SECTION 2 Energy Conversions..................... 157 SECTION 3 Conservation of Energy.................. 163 SECTION 4 Energy Resources...................... 167 Copyright © by Holt, Rinehart and Winston. 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Interactive Textbook iv Contents CHAPTER 10 Heat and Heat Technology SECTION 1 Temperature........................... 173 SECTION 2 What Is Heat?.......................... 179 SECTION 3 Matter and Heat....................... 187 SECTION 4 Heat Technology....................... 191 CHAPTER 11 Introduction to Atoms SECTION 1 Development of the Atomic Theory........ 199 SECTION 2 The Atom............................. 205 CHAPTER 12 The Periodic Table SECTION 1 Arranging the Elements.................. 213 SECTION 2 Grouping the Elements.................. 221 CHAPTER 13 Chemical Bonding SECTION 1 Electrons and Chemical Bonding.......... 229 SECTION 2 Ionic Bonds........................... 233 SECTION 3 Covalent and Metallic Bonds............. 237 CHAPTER 14 Chemical Reactions SECTION 1 Forming New Substances................ 243 SECTION 2 Chemical Formulas and Equations......... 247 SECTION 3 Types of Chemical Reactions............. 253 SECTION 4 Energy and Rates of Chemical Reactions... 257 Copyright © by Holt, Rinehart and Winston. 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Interactive Textbook v Contents CHAPTER 15 Chemical Compounds SECTION 1 Ionic and Covalent Compounds........... 263 SECTION 2 Acids and Bases....................... 267 SECTION 3 Solutions of Acids and Bases............. 273 SECTION 4 Organic Compounds.................... 277 CHAPTER 16 Atomic Energy SECTION 1 Radioactivity........................... 283 SECTION 2 Energy from the Nucleus................ 291 CHAPTER 17 Introduction to Electricity SECTION 1 Electric Charge and Static Electricity........ 297 SECTION 2 Electric Current and Electrical Energy....... 305 SECTION 3 Electrical Calculations................... 313 SECTION 4 Electric Circuits......................... 317 CHAPTER 18 Electromagnetism SECTION 1 Magnets and Magnetism................ 323 SECTION 2 Magnetism from Electricity............... 331 SECTION 3 Electricity from Magnetism............... 337 CHAPTER 19 Electronic Technology SECTION 1 Electronic Devices...................... 343 SECTION 2 Communication Technology.............. 349 SECTION 3 Computers............................ 357 Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook vi Contents CHAPTER 20 The Energy of Waves SECTION 1 The Nature of Waves................... 365 SECTION 2 Properties of Waves.................... 371 SECTION 3 Wave Interactions...................... 375 CHAPTER 21 The Nature of Sound SECTION 1 What Is Sound?........................ 381 SECTION 2 Properties of Sound.................... 387 SECTION 3 Interactions of Sound Waves............. 393 SECTION 4 Sound Quality......................... 399 CHAPTER 22 The Nature of Light SECTION 1 What Is Light?.......................... 403 SECTION 2 The Electromagnetic Spectrum............ 407 SECTION 3 Interactions of Light Waves............... 415 SECTION 4 Light and Color........................ 423 CHAPTER 23 Light and Our World SECTION 1 Mirrors and Lenses..................... 429 SECTION 2 Light and Sight......................... 435 SECTION 3 Light and Technology................... 439 Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook vii Contents Name Class Date CHAPTER 1 The World of Physical Science SECTION 1 Exploring Physical Science National Science BEFORE YOU READ Education Standards After you read this section, you should be able to answer PS 1a, 3a these questions: What is science? How are matter and energy related to physical science? What are the branches of physical science? What Is Science? You are eating soup and you see your reflection in the STUDY TIP spoon. It is upside down. You wonder, “Why is my reflec- Compare After you read tion upside down in a spoon, but not in a mirror?” Asking this section, make a chart questions like this one is the first step in doing science. comparing the two main branches of physical science. Science is a process of collecting information about the In the chart, describe what world. Much of the time, the first step in collecting infor- scientists in each branch study. mation is asking a question. You may not realize it, but you use science every day. When you use the brakes on your bicycle to slow down, you use your knowledge of science. You learned how hard you should apply the brakes by making observations. Say It Discuss In a small group, Making observations, asking questions, and trying to find talk about different ways the answers is what science is all about. that you use science in your everyday life. What causes high and low Why can I tides? see a reflection in a spoon? Why do I feel pain when I stub my toe? TAKE A LOOK 1. Identify What is often the ﬁrst step in gathering Part of science is asking information? questions about the world around you. Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 1 The World of Physical Science Name Class Date SECTION 1 Exploring Physical Science continued What Is Physical Science? Science is divided into many branches, or parts. Three major branches of science are Earth science, life science, and physical science. Physical science is the study of matter and energy. Matter is the “stuff” that everything is made of. Your STANDARDS CHECK shoes, your pencil, and the air you breathe are made PS 3a Energy is a property of many substances and is associated of matter. Energy is the ability to do work. Matter and with heat, light, electricity, energy are related because all matter has energy. mechanical motion, sound, nuclei, and the nature of a chemical. Sometimes, you can see or feel energy, such as light or Energy is transferred in many heat. Sometimes, you can tell that an object has energy ways. because it is moving. 2. Identify Give two All matter contains energy, even if you cannot see or examples of energy. feel the energy. For example, food contains energy. When you eat the food, you get energy from the food. You can use the energy to do all of your daily activities. TAKE A LOOK 3. Explain Why does the baseball have energy before the boy throws it? The baseball has energy even before the boy throws it, because it is matter, and all matter has energy. Why will paper burn, and gold will not? Why is throw- ing a bowling ball harder than throwing a baseball? How does water turn into steam? The answers to these ques- tions have to do with matter and energy. As you study more about physical science, you will learn more about matter and energy. You will see how matter and energy are related to each other. Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 2 The World of Physical Science Name Class Date SECTION 1 Exploring Physical Science continued What Are the Branches of Physical Science? Physical science is divided into two main branches: chemistry and physics. Both chemistry and physics can be divided into even smaller areas of study. For example, a smaller branch of chemistry is solid-state chemistry. Solid-state chemistry is the study of the reactions and behavior of solid materials. Another example is geophys- ics, a smaller branch of physics. Geophysics is the study of movements deep in the Earth. READING CHECK 4. Identify What are the two Physical Science main branches of physical science? is divided into Chemistry Physics has a branch called has a branch called Solid-state Chemistry Geophysics CHEMISTRY Chemistry is the study of the structure and properties of matter. The structure and properties of a substance determine how it interacts with other matter. For exam- ple, sugar dissolves in water. A diamond has a different structure and properties, so it doesn’t dissolve in water. The structure and properties of matter also affect Critical Thinking how it behaves under different conditions. For example, 5. Explain Why don’t all water is a liquid at room temperature. If the temperature substances behave the same way under the same decreases, the water may become solid. However, honey conditions? has a different structure and properties. It will become solid at a different temperature than water. Chemistry also includes the study of how matter changes. Substances can change during chemical reac- tions. A chemical reaction happens when one substance interacts with another substance to form a new sub- stance. Chemical reactions are happening all the time. When your body digests food, a chemical reaction is tak- ing place. Chemical reactions are what make flashlights work. They also allow car engines to run. Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 3 The World of Physical Science Name Class Date SECTION 1 Exploring Physical Science continued PHYSICS Critical Thinking The second area of physical science is physics. Like 6. Compare How is physics chemistry, physics has to do with matter. Physics is the different from chemistry? study of how energy affects matter. The study of physics can help you understand how a roller coaster works and what keeps it on its tracks. You can tell that a roller coaster has energy. When you study physics, you will learn what makes the roller coaster ride so exciting. Say It Why does a ball roll down a hill? Why doesn’t a brick Ask Questions Write roll down the same hill? How does a parachute let some- down four questions that one jump out of an airplane without getting hurt? How physics may be able to help you answer. Share your can a compass tell you which way is north? Physics can questions with a small group. help you answer questions like these. Motion, force, gravity, electricity, light, and heat are parts of physics. They are also things that you experience in your everyday life. For example, when you ride a bike, you are dealing with force and motion. If you fall off the bike, you are affected by gravity. How Do Other Branches of Science Use Physical Science? You learn about matter and energy when you study physical science. However, matter and energy are impor- tant in other branches of science, too. Many kinds of sci- entists use ideas from physical science in their work. Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 4 The World of Physical Science Name Class Date SECTION 1 Exploring Physical Science continued METEOROLOGY The study of Earth’s atmosphere, weather, and climate is called meteorology. Scientists who study meteorology are called meteorologists. You may have seen meteorolo- gists on the news, forecasting the weather. Other meteo- rologists study severe weather, such as hurricanes and tornadoes. They may be able to predict where severe weather will form so they can warn people. READING CHECK Before they can predict the weather, meteorologists 7. Deﬁne What is need to understand pressure, motion, and force. These meteorology? are ideas that you will study in physical science. GEOLOGY The study of the history, structure, and formation of Earth is called geology. One kind of geologist is a geo- chemist. A geochemist is a person who studies the chem- istry of rocks, minerals, and soil. Geochemists also need to know about heat and force to understand how parts of Earth formed and how they have changed. READING CHECK 8. Identify Give two reasons that geochemists need to understand physical science. This geochemist takes rock samples from the ﬁeld. Then, she studies them in her laboratory. BIOLOGY Believe it or not, life science and physical science are related. Chemistry and physics can explain many things that happen in biology. For example, a chemical reaction explains how animals get energy from food. Plants make sugar. Animals eat plants and breathe in oxygen. In animals, the sugar reacts with the oxygen to make carbon dioxide, water, and energy. You will learn about this and other chemical reactions when you study physical science. Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 5 The World of Physical Science Name Class Date Section 1 Review NSES PS 1a, 3a SECTION VOCABULARY physical science the scientiﬁc study of nonliving science the knowledge obtained by observing matter natural events and conditions in order to discover facts and formulate laws or principles that can be veriﬁed or tested 1. Identify What are three main branches of science? 2. Define What are matter and energy? How are they related? 3. Infer A scientist is studying the forces that act on a hockey puck. What branch of physical science is the scientist probably using? Explain your answer. 4. Explain Why does a meteorologist need to understand physics? 5. Apply Ideas You are building a go-cart. You want to know how you can make it go as fast as it can. Explain how you can use both chemistry and physics to help you build your go-cart. 6. Explain Why does a biologist need to understand chemistry? Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 6 The World of Physical Science Name Class Date CHAPTER 1 The World of Physical Science SECTION 2 Scientific Methods BEFORE YOU READ After you read this section, you should be able to answer these questions: What are the steps in scientific methods? How do scientists form a hypothesis? What do scientists do before telling others about their experimental results? What Are Scientific Methods? Two scientists wanted to find a better way to move STUDY TIP ships through the water. They thought that studying Outline As you read this sec- the way penguins swim might give them some ideas tion, make a chart showing how two scientists used the about how to improve ships. In this section, you will steps in scientiﬁc methods to learn how these scientists used scientific methods to improve ships. answer their questions. Scientific methods are the ways in which scientists answer questions and solve problems. As scientists look for answers, they often use the same steps. However, there is more than one way to use the steps. Look at the figure below. READING CHECK This figure shows six steps that are part of most scien- 1. Describe What are tific methods. Scientists may use all of the steps or just a scientiﬁc methods? few steps during an investigation. They may repeat some of the steps or do the steps in a different order. Steps of Scientiﬁc Methods Ask a Question Make Observations Form a Hypothesis Analyze Test the the Results Hypothesis TAKE A LOOK Draw Conclusions 2. Identify What is the No usual next step after Do they support your hypothesis? Communicate analyzing results? Yes Results Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 7 The World of Physical Science Name Class Date SECTION 2 Scientific Methods continued Why Do Scientists Ask Questions? Asking questions helps scientists focus on the reason for an investigation. Questions arise at every step of scientific methods. However, the question that becomes the focus of an investigation often comes from observation. Observation is the process of using your senses to collect information. REAL-WORLD EXAMPLE Two engineers, James Czarnowski and Michael Triantafyllou, wanted to improve the way ships moved through the water. An engineer is a scientist who builds things using scientific knowledge. Czarnowski and Triantafyllou used scientific methods to improve how READING CHECK ships move. 3. Describe What is an The two engineers studied how the propellers on ships engineer? work. They found that ships use a lot of fuel to push themselves through the water. They asked the question, “How can we make ships move faster with less fuel?” That is, they wanted to improve the efficiency of ships. A ship that is efficient does not use as much fuel as other ships to travel the same distance. The engineers looked to nature to find a way to make ships more efficient. They observed sea animals to learn how some of them swim faster than others. The engineers observed that penguins are very efficient swimmers. Penguins have stiff bodies, just like ships. However, they are able to push themselves through the water with ease. Now, the scientists had a new question. They wanted to know, “How can we make a ship that moves through the water more easily?” TAKE A LOOK 4. Identify How do penguins use their wings? Penguins use their wings as ﬂippers to “ﬂy” underwater. As their wings are pulled inward, they push against the water. This movement pushes the penguins forward. Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 8 The World of Physical Science Name Class Date SECTION 2 Scientific Methods continued How Do Scientists Form a Hypothesis? Once a scientist has made observations and asked a question, he or she is ready to predict an answer. This is called forming a hypothesis. A hypothesis (plural, hypotheses) is a possible explanation for, or guess at, an answer to a question. READING CHECK 5. Describe What is a A POSSIBLE ANSWER FROM NATURE hypothesis? The ship engineers had observed the slow movements of ships and the fast swimming of penguins. Their obser- vations led them to form a hypothesis. They guessed, “A propulsion system that imitates the way a penguin swims is more efficient than a system that uses propellers.” ANOTHER WAY TO WORD PREDICTIONS Critical Thinking Scientists often state their predictions as if-then 6. Explain How does an statements. For example, the engineers’ prediction if-then statement make it might have been: “If we use flippers instead of a propeller easier to determine whether a prediction is true? to move a boat, then it will be more efficient.” An if-then statement makes it easier to determine whether your prediction is true. The table below gives some examples of if-then statements. “If” statement “Then” statement If car A uses less gasoline than... then car A is more efﬁcient car B during the same trip... than car B. If more force is needed to stop an object with a large mass than... then force is an object with a small mass... needed to stop a large truck than a compact car. If a grape and an orange fall at... then, when dropped from TAKE A LOOK the same rate... the same height, they will hit the 7. Complete In the table, ground at time. complete the “then” statements. Why Do Scientists Test a Hypothesis? All hypotheses must be testable. A scientist tests a hypothesis by gathering more information or by doing an experiment. Scientists test a hypothesis to find out if it answers their question correctly. Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 9 The World of Physical Science Name Class Date SECTION 2 Scientific Methods continued CONTROLLED EXPERIMENTS One way to test a hypothesis is to do a controlled experiment. Suppose you want to know how much air will make a basketball bounce highest. You gather 15 bas- ketballs that are all made by the same company. All the basketballs are the same size and are made of the same material. You divide the basketballs into three groups. You inflate the balls in the first group with the amount of air that the maker recommends. You put more air in the balls in the second group. You put less air in the balls in the third group. Then, you drop each ball from the same height and measure how high it bounces. This is a controlled experiment. A controlled experiment is an experiment in which only one factor changes at a time. The factor that changes is called the variable. In your experiment, the variable was the amount of air in the balls. Everything READING CHECK else about the balls was the same. 8. Deﬁne What is a variable? Doing a controlled experiment allows a scientist to deter- mine the effects of a variable more easily. Suppose you had used basketballs that were not all made of the same material. It would have been harder to determine whether the air or the material caused some to bounce higher than others. Sometimes, it is not possible to do a controlled experi- ment. In these cases, scientists test their hypotheses by making observations or doing research. BUILDING A TEST BOAT The engineers who were trying to design an efficient boat thought they should test their hypothesis by build- ing one. They built Proteus, the penguin boat. It had flip- pers like a penguin so that the scientists could test their hypothesis about propulsion through the water. Proteus, 3.4 m long and 50 cm wide, was a specially built a boat used to test the “ﬂippers” hypothesis. Proteus has two flipperlike paddles, called foils. Both foils move out and then in, as the flippers of a penguin do. TAKE A LOOK 9. Identify What does b Proteus use instead of a Two car batteries supply energy to propeller to move through the motors that drive Proteus’s the water? flapping foils. c A computer controls the d number of times the As the foils flap, they push water foils flap per second. backward. The water pushes against the foils to propel the boat forward. Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 10 The World of Physical Science Name Class Date SECTION 2 Scientific Methods continued How Did the Scientists Test Proteus? Instead of using many groups, you can do a controlled experiment by repeating the test several times. For each test, you change one factor. That’s what the engineers did with Proteus. The engineers took Proteus to the Charles River in Boston. For each test, they paddled the boat across the river for the same distance with the same weather. The variable was the flapping rate of the flippers. READING CHECK 10. Identify What two factors stayed the same when Proteus was paddled across the river? 11. Identify What was the variable for each trip? Proteus, the “penguin boat,” was tested in the Charles River in Boston. The engineers collected data on the speed of the boat and the amount of energy used to move its flippers. Data (singular, datum) are pieces of information collected from experiments. The data recorded for the first trip were considered the control data. The control data were compared with the data from all of the other trips. READING CHECK The experimental part of the test began with the sec- 12. Deﬁne What are data? ond trip. The engineers changed the variable by increas- ing the flapping rate of the flippers. Then, they recorded the speed and the energy used during the trip. The engi- neers made several more experimental trips. Each time, they set a different flapping rate and collected data on the energy used and the speed. When all the data were collected, the engineers compared the results of the trips. They interpreted their results to find out which flapping speed used the least energy. That is, they learned which was the most efficient. Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 11 The World of Physical Science Name Class Date SECTION 2 Scientific Methods continued How Do Scientists Analyze Results? After scientists collect data, they must analyze it. To analyze data means to interpret what the data mean. One way to analyze data is to organize them into tables and graphs. Tables and graphs make the patterns in the data READING CHECK easier to see. 13. Describe What does it It’s always a good idea to perform your experiment mean to analyze data? several times. Repeated tests can tell you whether your data are accurate. If you get similar results every time, then you can be more sure that the results are accurate. If the results support your hypothesis, you know that your hypothesis is probably correct. ANALYZING PROTEUS The engineers collected data about the energy used and the speed of each trip. They used the data to calcu- late Proteus’s efficiency. Then, they made a graph of their data, shown below. Efficiency This graph shows the efﬁciency of Proteus Math Focus when the ﬂippers are moving at different 14. Analyze Which ﬂapping rates. rate gave Proteus the highest efﬁciency? 0.7 1.2 1.7 2.2 Flaps per second The scientists also used the data to compare the effi- ciency of Proteus with the efficiency of a regular boat. That analysis is shown in the bar graph below. 87% This graph shows the Math Focus 70% efﬁciency of Proteus compared with the 15. Compare Which boat efﬁciency of a was more efﬁcient? How propeller-driven boat. much more efﬁcient was it? Propeller- Proteus driven boat Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 12 The World of Physical Science Name Class Date SECTION 2 Scientific Methods continued What Are Conclusions? At the end of the investigation, you must draw a con- clusion. You do this by looking at your analysis. The results tell you whether your hypothesis was correct. If it was, then you can say that your results support your hypothesis. That is your conclusion. It’s also possible that you will come to a different conclu- sion. You may decide that your results do not support your hypothesis. If so, you can change the procedure, gather more information, or ask new questions. Whether your hypothesis is supported or not, the results are always important. PROTEUS CONCLUSION The engineers found that penguin propulsion was more efficient than propeller propulsion. They concluded that the results supported their hypothesis. READING CHECK The scientists were able to reach this conclusion 16. Explain Why did the because they did many tests. They were careful to control engineers think that their all the factors except the variable. They measured every- hypothesis was correct? thing accurately. This showed that their results were not accidental. Their data showed the same relationship many times. Therefore, their results were probably accurate. Drawing a conclusion to support your hypothesis usu- ally leads to more questions. More questions lead to more investigations. This is how scientific progress continues. How Do Scientists Share Results? Other scientists will want to know your results. Some will want to conduct their own tests based on your results. There are three ways to communicate the results of your investigation to them. You can use any or all of them. READING CHECK 17. Identify What are Method of communicating results Audience three ways scientists Write a paper for a scientiﬁc journal. scientists and others who communicate the results of read the journal their investigations? Give a talk. scientists and others who attend the talk Create a Web site. anyone interested in the work Sharing your results allows other scientists to continue your work. Sharing also makes it possible for others to do your experiments and support your results. Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 13 The World of Physical Science Name Class Date Section 2 Review SECTION VOCABULARY data any pieces of information acquired through observation the process of obtaining informa- observation or experimentation tion by using the senses hypothesis a testable idea or explanation that scientiﬁc methods a series of steps used to leads to scientiﬁc investigation solve problems 1. Identify Fill in the missing steps in the table. Steps in Scientiﬁc Methods Form a hypothesis. Test the hypothesis. 2. Infer A synonym is a word that has the same meaning as another word. What are two synonyms for hypothesis? 3. Interpret a Graph According to the graph, at what Efficiency of Proteus flapping rate was Proteus least efficient? Efficiency 0.7 1.2 1.7 2.2 Flaps per second 4. Define What is a controlled experiment? 5. Describe How can a scientist do a controlled experiment if it is not possible to use several different groups? 6. Explain How can a scientist test a hypothesis if it is not possible to do a con- trolled experiment? Give two ways. Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 14 The World of Physical Science Name Class Date CHAPTER 1 The World of Physical Science SECTION 3 Scientific Models BEFORE YOU READ After you read this section, you should be able to answer these questions: What are the three types of scientific models? How do scientists use models to help them understand scientific information? What Is a Scientific Model? The engineers who built the ship Proteus wanted to STUDY TIP copy the way that a penguin swam. Proteus does not Compare After you read this have feathers and is not alive. However, the way Proteus section, make a chart com- paring scientiﬁc theories and moves in the water is similar to the way a penguin moves scientiﬁc laws. in the water. Proteus is a model that helps engineers learn about how objects can move through the water. A model is something that scientists use to represent an object or process. For example, models of human body systems help you learn how the body works. Models Critical Thinking can help you learn about the past. They can even help 1. Compare A globe is a to predict the future! However, a model cannot tell you model of the Earth. Give one everything about the thing it represents. This is because way that a globe is similar to the Earth and one way that the model always has a least a few differences from what they are different. it represents. There are three common kinds of scientific models: physical models, mathematical models, and conceptual models. TAKE A LOOK 2. Infer Why would a scientist use a spring toy to model a sound wave? The coils on this spring toy can be used as a physical model of a sound wave. We cannot see a sound wave. The spring toy shows how a sound wave acts. Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 15 The World of Physical Science Name Class Date SECTION 3 Scientific Models continued PHYSICAL MODELS A physical model is a model that you can see and touch. Some physical models can help you study things that are too small to see. For example, a ball-and-stick model can show what a molecule is made of. Some physical models show the Say It shape of something that’s invisible. For example, you can’t Brainstorm In a small see a sound wave. However, a spring toy, such as the one on group, come up with a list of the previous page, can show you how a sound wave acts. 10 kinds of physical models. Talk about how they are similar Other physical models can help you study things that to the things they represent are too large to see all at once. For example, you can’t and how they are different. see the whole Earth or all of the solar system. Models help you picture in your mind what they look like. A physical model can also help you understand a con- cept. Launching a model of a space shuttle can help you understand how a real space shuttle is launched. MATHEMATICAL MODELS A mathematical model is made of mathematical equations and data. You can’t see a mathematical model the way you can see a physical model. However, you can use it to under- stand systems and make predictions. Meteorologists put tem- perature, air pressure, wind speed, and precipitation data into mathematical models to understand weather systems. They also use mathematical models to predict the weather. Some mathematical models are simple. Others are very difficult and need computers to make them work. CONCEPTUAL MODELS Conceptual models are used to help explain ideas. Some conceptual models are systems of many ideas. You may have heard about the big bang theory. It is a concep- tual model that explains how the planets and galaxies formed. Most scientists accept the big bang theory, even though some data do not fit the model. Model Type of Model The big bang theory Ball-and-stick model of a molecule TAKE A LOOK 3. Identify Fill in the blanks Equation that shows how a particle mathematical in the table to tell whether acts in a magnetic ﬁeld the example is a physical, Computer simulation of the path of mathematical, or conceptual a tornado model. Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 16 The World of Physical Science Name Class Date SECTION 3 Scientific Models continued How Do Models Help Build Scientific Knowledge? Models are used to show ideas and objects in science. They are also used to help scientists learn new things. SCIENTIFIC THEORIES Models are often used to help explain scientific theo- ries. In science, a theory is an explanation for many hypotheses and observations. Theories are supported by many tests and observations. A theory can explain why something happens and can predict what will happen in the future. READING CHECK Scientists use models to help them look for new scientific 4. Deﬁne What is a scientiﬁc information. The new information can support a theory or theory? show that it is wrong. This is all part of science. As scientists make new observations, new theories are developed over time. New theories replace old theories that are shown to be wrong. The figure below shows an old model of the atom and the new model that replaced it. TAKE A LOOK 5. Explain Why might scientists come up with a new theory? 1897 atomic model Current atomic model These drawings are both models of an average atom. The old model shows what scientists understood about atoms in 1897. The new model replaced the old model as scientists made more observations. SCIENTIFIC LAWS When a model correctly predicts the results of many different experiments, a scientific law can be made. In science, a law is a summary of many experimental results and observations. It tells you how things work. A law is different from a theory. A law tells you only what happens, not why it happens. An example of a scientific law is the law of conservation of mass. It says that in a chemical change, the total mass doesn’t change. The law doesn’t explain why this happens or make any predictions. It tells you only what happens during any chemical change. Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 17 The World of Physical Science Name Class Date Section 3 Review SECTION VOCABULARY law a descriptive statement or equation that theory a system of ideas that explains many reliably predicts events under certain conditions related observations and is supported by a model a pattern, plan, representation, or large body of evidence acquired through description designed to show the structure or scientiﬁc investigation workings of an object, system, or concept 1. Explain What are some ways that scientists use models? 2. Identify What are the three types of models used by scientists? 3. Identify A model of a molecule can help you imagine what a molecule looks like. What are two ways that this model is different from the object it represents? 4. Compare What is the difference between a scientific theory and a scientific law? 5. Explain How can theories change over time? 6. Explain Why can’t you use a model to learn everything about an object? Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 18 The World of Physical Science Name Class Date CHAPTER 1 The World of Physical Science SECTION 4 Tools, Measurement, and Safety BEFORE YOU READ After you read this section, you should be able to answer these questions: What tools do scientists use to make measurements? What is the International System of Units? How can you stay safe in science class? What Kinds Of Tools Do Scientists Use? A tool is anything that helps you do something. STUDY TIP Scientists use many tools to help them make observa- Outline As you read, tions and do experiments. Some tools are used to take underline the main ideas in each paragraph. When measurements. These include stopwatches, metersticks, you ﬁnish reading, make an thermometers, balances, and spring scales. Making mea- outline of the section using surements is one way that scientists gather data. the ideas you underlined. You can use a You can use a stopwatch to spring scale to measure time. measure force. TAKE A LOOK 1. Identify What tool can you use to measure time? Tools can also help you analyze the data you have col- lected. A pencil and graph paper are tools that have been used to graph data for years. A calculator is a tool that can help you do calculations quickly. A graphing calculator can show your data in a graph. A computer can display your Critical Thinking 2. Predict Consequences data in many ways. What might happen if sci- entists in different countries used different systems of How Do Scientists Take Measurements? measurement? Many years ago, scientists in different countries used different systems of measurement. They needed a simple measurement system that everyone could use. This would help them share their data more easily. Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 19 The World of Physical Science Name Class Date SECTION 4 Tools, Measurement, and Safety continued THE INTERNATIONAL SYSTEM OF UNITS Over time, the metric system was set up. It is also known as the International System of Units (SI). This simple system was one that every country could use to compare measurements. All of the SI units are written in multiples of 10. This makes it easy to change from one unit to another. Some of the units in the SI are shown in READING CHECK the table below. 3. Explain Why is it easy to Common SI Units change from one SI unit to another? Length meter (m) kilometer (km) 1 km 1,000 m decimeter (dm) 1 dm 0.1 m centimeter (cm) 1 cm 0.01 m millimeter (mm) 1 mm 0.001 m micrometer (μm) 1 μm 0.000 001 m nanometer (nm) 1 nm 0.000 000 001 m Area square meter (m2) square centimeter (cm2) 1 cm2 0.0001 m2 Volume cubic meter (m3) cubic centimeter (cm3) 1 cm3 0.000 001 m3 liter (L) 1 L 1 dm3 0.001 m3 milliliter (mL) 1 mL 0.001 L 1 cm3 Math Focus Mass kilogram (kg) gram (g) 1 g 0.001 kg 4. Calculate How many milligram (mg) 1 mg 0.000 001 kg millimeters are in 50 km? Temperature Kelvin (K) 0°C 273 K Celsius (°C) 100°C 373 K LENGTH The length of an Olympic-sized swimming pool is measured in meters (m). A meter is the basic SI unit of length. Other SI units of length are larger or smaller than the meter by multiples of 10. For example, 1 millimeter (mm) is one one-thousandth of a meter. That means that if 1 m is divided into 1,000 equal parts, each part is 1 mm. MASS Mass is a measure of how much matter is in an object. The kilogram (kg) is the basic SI unit for mass. The kilogram is used to describe the mass of large objects, such as people. Grams (g) are used to describe the mass READING CHECK of smaller objects, such as apples. One kilogram equals 5. Deﬁne What is mass? 1,000 g. Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 20 The World of Physical Science Name Class Date SECTION 4 Tools, Measurement, and Safety continued VOLUME Volume is the amount of space that something fills. Liquid volume is given in liters (L). A liter is based on the meter. One cubic meter (1 m3) equals 1,000 L. Therefore, 1,000 L of liquid will fit exactly into a box that is 1 m on each side. READING CHECK You can find the volume of a box-shaped object by 6. Identify What units are multiplying its length, width, and height together. The used to give the volume of volume of a large solid is given in cubic meters (m3). The liquids? volume of a small solid is given in cubic centimeters (cm3). DENSITY Density is a measure of how much matter is in a given volume. You cannot measure density directly. It is known as a derived quantity because you must calculate it from other, known quantities. You can find the density of an object using the following equation: density mass volume TEMPERATURE The temperature of a substance is the measurement of how hot (or cold) it is. The kelvin (K, without a degree sign) is the SI unit for temperature. Degrees Fahrenheit (°F) and degrees Celsius (°C) are also used. READING CHECK 7. List Give three units What Are Safety Rules? that are used to measure Science is exciting and fun, but it can be dangerous. temperature. There are many safety rules that you must follow when- ever you do an experiment. Always listen to your teacher’s instructions. Don’t take shortcuts. Read lab directions carefully. Pay attention to safety information. The safety symbols in the figure below are important. Learn them so that you, and others, will be safe in the lab. Safety Symbols Eye Clothing Hand Heating Electrical protection protection safety safety safety Chemical Animal Sharp Plant safety safety object safety Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 21 The World of Physical Science Name Class Date Section 4 Review SECTION VOCABULARY density the ratio of the mass of a substance to temperature a measure of how hot (or cold) the volume of the substance something is; speciﬁcally, a measure of the aver- mass a measure of the amount of matter in an age kinetic energy of the particles in an object object volume a measure of the size of a body or region in three-dimensional space 1. Identify What are two tools that can be used to measure the length of an object? 2. Compare How is the mass of an object different from its density? 3. Calculate A ball falls from a height of 25 cm. What is the same distance described in meters? Show your work. 4. Identify What unit is usually used to describe the volume of a liquid? A solid? 5. Calculate What is the volume of a box that is 3 m long, 0.5 m high, and 2 m wide? Show your work. 6. Analyze What safety symbols would you expect to see for an experiment that asks you to pour acid into a beaker? Give three possibilities. Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 22 The World of Physical Science Name Class Date CHAPTER 2 The Properties of Matter SECTION 1 What Is Matter? National Science BEFORE YOU READ Education Standards After you read this section, you should be able to answer PS 1a, 1c these questions: What is matter? What is volume and mass? What are mass and weight? What is inertia? What Is Matter? You are made of matter. Matter is anything that has STUDY TIP mass and takes up space. A toaster, a glass of water, and Organize Information In the air around you are all made of matter. your notebook, make a table with three columns. Label Matter can be described by its properties. Several proper- the ﬁrst column Property of ties of matter are volume, mass, and weight. The liter (L) is Matter, the second column a scientific unit of volume. The kilogram (kg) is the SI unit Deﬁnition, and the third column Unit of Measure. As for mass, and the newton (N) is the SI unit of weight. you read, ﬁll in the columns. What Is Volume? READING CHECK All matter takes up space. The amount of space that an object takes up is known as the object’s volume. 1. Identify Give a unit of measure for each of the Imagine a car driving into a full swimming pool. Some following properties: water would splash out. This happens because the car volume: and the water have volume. Two objects can’t occupy the mass: same space at the same time. weight: UNITS OF VOLUME The SI unit of volume is the cubic meter. The figure READING CHECK below shows how big a cubic meter is. 2. Deﬁne What is volume? The liter (L) is used more often as the scientific unit for measuring volume. Small volumes of liquid are often given in milliliters (mL). Remember that 1 L equals 1,000 mL. Any volume of liquid can be described in liters or milliliters. For example, the volume of a small can of soda is measured as 0.355 L or 355 mL. Math Focus 3. Convert The volume of a one half gallon carton of milk A girl is in a one cubic meter box is 1.9 L. How many milliliters holding a meter stick. is 1.9 L? Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 23 The Properties of Matter Name Class Date SECTION 1 What Is Matter? continued MEASURING LIQUID VOLUME At home, you may use a measuring cup to determine a liquid’s volume. In class, you may use graduated cylinders to measure volume. When you measure an amount of liquid, you must be careful. If you look closely, you will see that the surface of water is curved in a glass container. The curve of the READING CHECK surface of a liquid is called a meniscus. 4. Describe What is a The meniscus may curve only a small amount, and meniscus? may look flat in a large glass container. The amount of liquid in a container is measured from the lowest point of the meniscus. When you look at the figure below, you can see a meniscus. 7 mL 5 mL To measure volume correctly, read the scale at the lowest point of the meniscus. The volume here equals 4.0 mL. TAKE A LOOK 3 mL 5. Draw On the ﬁgure, draw a meniscus that would show 1 mL a volume of 6.0 mL. VOLUME OF A REGULARLY SHAPED SOLID OBJECT The volume of any regularly shaped solid object is mea- sured in cubic units. The word cubic means that the object is not flat. The volume of an object is calculated by multi- plying three measurements: length, width, and height. It is important to see the difference between cubic measurements, which mean volume, and square measurements, which mean area. The figure below READING CHECK shows the difference between volume and area. 6. Identify What do cubic measurements measure? 7. Identify What do square 1m 1m measurements measure? 1m 1m 1m Cube Square The cube has volume. Each face of the cube has area. The square has only area. Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 24 The Properties of Matter Name Class Date SECTION 1 What Is Matter? continued FINDING THE VOLUME OF A REGULARLY SHAPED OBJECT A formula is used to calculate the volume of a regu- larly shaped object. An example of a regularly shaped object is a cube. V 1 m 1 m 1 m 1 m3 Height A cube whose length, width, and height are each 1 m has a volume Critical Thinking of one cubic meter (1 m3). 8. Find What is the area of each face of the cube shown in the ﬁgure? Remember that area is length multiplied by width. Length Width To find the volume (V) of a regularly shaped object, multiply the area (A) and height (h) as shown in the following formula: VAh Let’s do a problem. What is the volume of a box that has an area of 400 cm2 and a height of 10 cm? VAh V 400 cm 10 cm 4,000 cm3 2 VOLUME OF AN IRREGULARLY SHAPED OBJECT One way to measure the volume of an irregularly shaped object is to put it into a known volume of water. The increase in volume is equal to the volume of the object. Remember that objects cannot occupy the same space at the same time. The figure below shows how much water is READING CHECK displaced or moved after an object is dropped into it. 9. Describe You are given a toy metal car and asked ML ML to ﬁnd its volume. Describe how you would do this. ML ML ML ML ML ML The irregularly shaped solid makes the total volume 2 mL larger. So, its volume is 2 mL. Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 25 The Properties of Matter Name Class Date SECTION 1 What Is Matter? continued What Is Mass? Another property of matter is mass. Mass is a measure of the amount of matter that makes up an object. For example, both you and a penny are made of matter. You are made up of more matter than the penny, so you have READING CHECK a greater mass. 10. Describe What does the The mass of an object does not change when the mass of an object measure? location of the object changes. The mass of any object [2 WORs] [the amount of changes only when the amount of matter that makes up matter in an object] the object changes. DIFFERENCE BETWEEN MASS AND WEIGHT You may think that the terms mass and weight mean the same thing, but they are very different. Weight is the measure of the force of gravity on an object. Earth has a force of gravity that keeps all objects from floating into space. When you step on a scale, you are seeing how much force Earth pulls on you. This is known as your READING CHECK weight. 11. Identify When you step An object’s weight can change depending on where the on a scale, what is being object is located. The mass of the object stays the same. measured? For example, a penny would weigh less on the moon than here on Earth. This happens because the moon has less mass and has a lower force of gravity than Earth does. The mass, or amount of matter in the penny, stays the same. Only the force of gravity changes. The table below shows how mass and weight differ. Mass Weight Say It How it is with a balance with a scale Brainstorm Form a small measured? group. Discuss what it would be like to have a soccer game What is the amount of matter the force of gravity on the moon. Think about measured? how large the ﬁeld might be and the weight of the ball. SI kilograms newtons measurement units TAKE A LOOK 12. Completion Fill in the Changes with two empty boxes. Write the location of the object? either yes or no. Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 26 The Properties of Matter Name Class Date SECTION 1 What Is Matter? continued MEASURING MASS AND WEIGHT The brick and the sponge in the figure below have the same volume. This is because the brick has larger mass, so Earth pulls on the brick more than it does on the sponge. Therefore, the brick weighs more than the sponge. The brick and the sponge take up the same amount of space. The brick contains more matter, so its mass—and thus its weight—is greater. The SI unit for mass is the kilogram (kg). Smaller masses are often measured in grams (g) or milligrams (mg). These units can be used to give the mass of any object. READING CHECK Weight is a measure of gravitational force. The SI unit 13. Identify Name three of weight is the newton (N). One newton is equal to the mass units. weight of an object on Earth with a mass of about 100 g. What Is Inertia? Imagine kicking a soccer ball that has the mass of a bowling ball. It would not only be painful but also very READING CHECK difficult to move the ball. The reason is inertia. Inertia 14. Identify What is the SI is the ability of an object to resist a change in its motion. unit for force and its symbol? Therefore, an object will stay at rest unless something causes the object to move. Also, a moving object will keep moving unless something causes it to change speed or direction. READING CHECK The mass of an object tells you how much inertia an 15. Identify What is inertia? object has. An object with a large mass is harder to get moving and harder to stop than an object with less mass. The reason is that the object with the larger mass has more inertia. For example, a truck has more inertia than a bicycle. If you were trying to get a truck moving by pushing on it, you might not be able to get it moving at all. It is much easier to change the motion of a bicycle. READING CHECK 16. Identify What does the mass of an object tell you about its inertia? Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 27 The Properties of Matter Name Class Date Section 1 Review NSES PS 1a, 1c SECTION VOCABULARY inertia the tendency of an object to resist being meniscus a curve at a liquid’s surface by which moved or, if the object is moving, to resist a one measures the volume of a liquid. change in speed or direction until an outside volume a measure of the size of a body or force acts on the object region in three-dimensional space. mass a measure of the amount of matter in weight a measure of the gravitational force an object exerted on an object; its value can change with matter anything that has mass and takes up space the location of the object in the universe. 1. Describe Why is an apple an example of matter? 2. Explain What is the difference between mass and weight? 3. Identify In the figure below, what is the volume of water in the graduated cylinder? M, 4. Determine A rock is placed into a graduated cylinder containing 80 mL of water. What is the volume of the rock if the water level rises to the 120 mL mark? 5. Calculate One airline limits the size of carry-on luggage to a volume of 40,000 cm3. A passenger has a carry-on that has an area of 1,960 cm2 and is 23 cm high. Is the passenger’s luggage OK to carry on the airplane? Show work to prove your answer. Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 28 The Properties of Matter Name Class Date CHAPTER 2 The Properties of Matter SECTION 2 Physical Properties National Science BEFORE YOU READ Education Standards After you read this section, you should be able to answer PS 1a, 1b these questions: What are physical properties of matter? What is density? What is a physical change? What makes objects float or sink? What Are Physical Properties of Matter? We use one or more of our senses to identify an object. STUDY TIP The properties we are sensing are the physical proper- Ask Questions Read this ties of the object. A physical property of matter can be section silently. In your science notebook, write questions that detected and measured without making a new substance. you have about this section. If a new substance is made, a chemical property was Underline all words you do measured. Chemical properties will be covered in the not understand. next section. There are many physical properties that can help you READING CHECK identify an object. Some physical properties are color, 1. Describe What are odor, texture, and shape. How could you identify a fruit physical properties? as an apple? You would probably first look at its color and shape. Its odor and certainly its taste may confirm that the fruit is an apple. Other physical properties of an object include its strength, flexibility, ability to conduct electricity, and magnetism. Some important examples of the physical properties of matter can be seen in the table below. Physical Property Description Critical Thinking Thermal conductivity How heat moves through a substance 2. Applying Concepts You Ductility The ability of substance to be pulled are given two balls that are into wire made from the same rubber. State The physical form of matter (solid, They are also the same size liquid, or gas) and color. One is hollow and Malleability The ability of a substance to be rolled one is solid. Give three into a shape physical properties that could Solubility The ability of a substance to dissolve be used to identify the ball that is solid. Density How compact a substance is Compressibility The ability to be squeezed or pressed together Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 29 The Properties of Matter Name Class Date SECTION 2 Physical Properties continued DENSITY Density is a physical property of matter that describes how its mass and volume are related. Density is the amount of matter in a given volume. A golf ball and ping pong ball have similar volumes, so they occupy about the same amount of space. But since the golf ball has more mass, it has a greater density than the ping pong ball READING CHECK does. Take a look at the figure below. 3. Describe What is density a measure of? Mass 46 g A golf ball is denser than a ping pong ball because the golf ball contains more Mass 3 g matter in a similar volume. Math Focus A formula is used to find the density of an object. To 4. Determine How much more matter is in a golf ball find an object’s density (D), you first measure its mass than a ping pong ball? (m) and volume (V). Then use the formula below. D _m_ V The units of density are a mass unit (kg or g) divided by a volume unit (L, mL, or cm3). For example, a density unit could be grams per cubic centimeter (g/cm3) for sol- ids, and grams per millimeter (g/mL) for liquids. The den- sity of a substance does not depend on how much of the substance you may have. One kilogram of iron has the same density as one gram of iron. How Is the Density Determined? When you are given a density problem, follow the fol- lowing procedure: Step 1: Write the density equation D _m_ V Step 2: Replace m and V with the measurements given in the problem. Math Focus 5. Calculate What is the Let’s try a problem. What is the density of mercury if density of gold if 28 g (1 oz) 270 g of mercury has a volume of 20 mL? of gold has a volume of 1.45 cm3? Show your work. D _m_ V 270 g D ______ 13.5 g/mL 20 mL Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 30 The Properties of Matter Name Class Date SECTION 2 Physical Properties continued USING DENSITY TO IDENTIFY SUBSTANCES Density is a useful physical property. It can be used to help identify a substance. When measured at the same temperature and pressure, the density of a substance READING CHECK is always the same. The density of some common sub- 6. Describe Under what stances can be seen in the table below.

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