FOCUS ON PHYSICAL SCIENCE (16)

When you read Focus On Physical Science, you are reading for information Science is nonfiction writing—it describes reallife events, people, ideas, and technology Here are some tools that Focus On Physical Science has to help you read Before You Read By reading /…iÊ Ê`i> and >ˆ˜Ê`i> prior to reading the chapter or lesson, you will get a preview of the coming material Density and Buoyancy /…iÊ Ê`i> A fluid exerts an upward force on an object that is placed in the fluid LESSON 8.a, 8.b, 9.f Density On the first page of each chapter you will find /…iÊ Ê`i> The Big Idea is a sentence that describes what you will learn about in the chapter >ˆ˜Ê`i> The density of a material is a measure of how much matter is packed into a unit volume of the material 8.c Pressure and the Buoyant Force LESSON >ˆ˜Ê`i> Objects in a fluid experience a buoyant force resulting from the pressure exerted by the fluid 8.d, 9.f Sinking and Floating LESSON >ˆ˜Ê`i> An object will float in a fluid if the density of the object is less than the density of the fluid LESSON Science Content Standards 8.a Students know density is mass per unit volume 8.b Students know how to calculate the density of substances (regular and irregular solids and liquids) from measurements of mass and volume 9.f Apply simple mathematic relationships to determine a missing quantity in a mathematic expression, given the two remaining terms (including speed ϭ distance/time, density ϭ mass/volume, force ϭ pressure ϫ area, volume ϭ area ϫ height) Reading Guide What You’ll Learn ▼ Explain how the density of a material is independent of the amount of the material ▼ Calculate the density of an object given its mass and volume Floating on Air Density These hot-air balloons weigh hundreds of pounds, but still are able to rise through the air A hot-air balloon has three main parts—the balloon envelope, the burner, and the basket When the burner heats the air inside the envelope, the envelope expands and the balloon rises What forces push the balloon upward? >ˆ˜Ê`i> The density of a material is a measure of how much matter is packed into a unit volume of the material Real-World Reading Connection Can you imagine trying to lift a rock that is as big as a basketball? The rock and the basketball are the same size, but the rock is much heavier because it has more matter packed into the same volume of space -Vˆi˜ViÊÊ+PVSOBM Compare and contrast three objects that float with three objects that sink 126 What is density? Which would have more mass, the balloon filled with air or the bottle of water shown in Figure 1? The mass of an object depends not only on the size of the object, but also on the material the object contains All materials, such as the air in the balloon and the water in the bottle, have a property called density Density (DEN suh tee) is the amount of mass per unit volume of a material Matter is made of particles, such as atoms or molecules, that have mass The density of a material depends on the masses and the number of particles packed into a given volume Figure shows that the volume of air has fewer particles and less mass than the same volume of water As a result, the density of air is less than the density of water ▼ Describe how to measure the density of a liquid and a solid Figure The balloon has less mass because it contains fewer particles of matter than the water in the bottle does Source: Chapter 3, p 126 /…iÊ Ê`i> is divided into Main Ideas Each lesson of the chapter has a >ˆ˜Ê`i> that describes the focus of the lesson Compare the density of air to the density of water Why It’s Important Density can be used to determine the identity of unknown materials Other Ways to Preview Vocabulary density rectangular solid • Read the chapter title to find out what area of science you will study Review Vocabulary volume: the amount of space taken up by an object (p 10) 130 • Skim the photo, illustrations, captions, graphs, and tables Chapter • Density and Buoyancy Source: Chapter 3, Lesson 1, p 130 xxx • Look for key terms that are boldfaced and highlighted The Get Ready to Read section allows you to learn, practice, and apply a reading skill before you start reading the chapter’s first lesson Target Your Reading will help you keep the main idea in focus as you read the chapter Get Ready to Read New Vocabulary ELA8: R 1.3 Target Your Reading Use this to focus on the main ideas as you read the chapter Before you read the chapter, respond to the statements below on your worksheet or on a numbered sheet of paper • Write an A if you agree with the statement • Write a D if you disagree with the statement After you read the chapter, look back to this page to see if Learn It! What should you if you find a word you don’t know or understand? Here are some suggested strategies: Use context clues (from the sentence or the paragraph) to help you define it Look for prefixes, suffixes, or root words that you already know Write it down and ask for help with the meaning Guess at its meaning Look it up in the glossary or a dictionary you’ve changed your mind about any of the statements • If any of your answers changed, explain why • Change any false statements into true statements • Use your revised statements as a study guide Before You Read A or D Practice It! containragraph Read a pa word from cabulary en, go ing a vo d to en Th g in nn begi e the determin d back to or w of the meaning Look at the word vertical in the following passage See how context clues can help you understand its meaning Statement After You Read A or D Density is calculated by dividing volume by mass Air pressure increases as you climb a mountain Things can float only in liquids such as water Context Clue Think about the forces acting on the boat in Use Figure 13 to see an example of vertical forces All fluids are liquids Figure 13 Gravity is pulling the boat down, yet the boat doesn’t accelerate downward Because the boat is not accelerating up or down, the vertical forces on the boat are balanced There must be an upward force balancing the downward force of gravity that keeps the sailboat from sinking —from page 146 Context Clue Up and down describe vertical forces You calculate the volume of all solids by multiplying length times width times height Heavy things sink when placed in water Print a worksheet of this page at ca8.msscience.com Context Clue The upward and downward forces are balanced Apply It! Make a vocabulary bookmark with a strip of paper As you read, keep track of words you not know or want to learn more about Compared to liquids, particles in gases are very close together Only solid objects can exert forces Hot-air balloons can fly because they are less dense than air 10 Air pressure only pushes down on you Pressure in All Directions 128 Source: Chapter 3, pp 128–129 EgZhhjgZ As You Read 129 If the pressure exerted by a fluid is a result of the weight of the fluid, is the pressure in a fluid exerted only downward? The illustration in Figure 11 shows a small, solid cube in a fluid The fluid exerts pressure on each face of this cube, not just on the top The pressure is perpendicular to the surface, and the amount of pressure depends only on the depth in the fluid As shown in the photograph in Figure 11, this is true for any object in a fluid, no matter how complicated the shape The pressure on the object is always perpendicular to the surface of the object In which direction does pressure exerted by a fluid push? EgZhhjgZ Atmospheric Pressure Within each lesson you will find tools that will help you understand what you read Figure 11 Phonetic spellings show you how to say difficult words They show the spelling for how to say each syllable Here is an example that you would find in the text: atmospheric (AT muh sfihr ik) pressure The pressure on an object of any shape is exerted perpendicular to the surfaces of the object Explain why the arrows showing the pressure have different lengths questions help you check your reading understanding When you read about the pressure in fluids, you might think only about liquids such as water However, remember that gases are fluids, too Like liquids, a gas exerts pressure on an object depending on the height of the gas above the object Atmospheric (AT muh sfihr ik) pressure is the force exerted per unit area by air particles If you start at the top of a mountain and walk down, the height of the column of air above you increases This means that atmospheric pressure increases as your elevation decreases Figure 12 shows how pressure varies as you go from the tallest mountains to deep under water in the ocean You can sense the change in atmospheric pressure when you fly in an airplane or take an elevator to the top of a tall building The sudden change in pressure can make your ears pop You sometimes can feel changes in pressure, but you probably don’t notice the air pressing on you right now The column of air above you is more than 10 km thick The total force of the air pushing on the surface area of your skin is about the same as the weight of ten cars! You don’t feel this pressure because there is an equal, internal pressure pushing out from the inside of your body This internal pressure balances the external pressure exerted on you by the atmosphere 144 Chapter • Density and Buoyancy Source: Chapter 3, Lesson 2, p 144 xxxi Other Skills to Exercise as You Read Question Compare and Contrast Sentences • What is the >ˆ˜Ê`i> ? • Look for clue words and phrases that signal • What is /…iÊ Ê`i> ? comparison, such as similar to, just as, both, in common, also, and too • Look for clue words and phrases that signal Connect • As you read, think about people, places, and situations you’ve encountered Are there any similarities with those in Focus On Physical Science? • Can you relate the information in Focus On Physical Science to other areas of your life? Predict • Predict events or outcomes by using clues and information you already know • Change your prediction as you read and gather new information contrast, such as on the other hand, in contrast to, however, different, instead of, rather than, but, and unlike Cause-and-Effect Sentences • Look for clue words and phrases such as because, as a result, therefore, that is why, since, so, for this reason, and consequently Sequential Sentences • Look for clue words and phrases such as after, before, first, next, last, during, finally, earlier, later, since, and then Visualize • Create a picture in your mind about what you are reading Picture the setting—for example, a laboratory, a roller coaster, or a mountain • A mental image can help you remember what you read for a longer time After You Read Follow up your reading with a summary and an assessment of the material to evaluate if you understood the text Summarize Assess • Describe /…iÊ Ê`i> and how the details • What was /…iÊ Ê`i> ? support it • Describe the >ˆ˜Ê`i> and how the details support it • Use your own words to explain what you read • Complete the Summary Activity at the end of the lesson xxxii • What was the >ˆ˜Ê`i> ? • Did you learn anything new from the material? • Can you use this new information in other school subjects or at home? • What other sources could you use to find out more information about the topic? Follow the tour through the next few pages to learn about using your textbook, Focus On Physical Science This tour will help you understand what you will discover as you read Focus On Physical Science Before you begin reading, take the tour so that you are familiar with how this textbook works Unit Preview West-Coast Events Time Line See significant events that occurred on the West Coast of the United States and compare them to events that occurred around the world World Events Time Line See significant events that occurred around the world and compare them to events that occurred on the West Coast Science Online A visual reminder to explore online tools to learn more about a scientist’s career Motion and Forces To learn more about physicists and their work, visit ca8.msscience.com The Speed of Sound Forces of jet engines that can move planes faster than speed of sound cause a vapor cloud that occurs at near speed of sound from changes in pressure Interactive Time Line To learn more about these events and others, visit ca8.msscience.com Construction begins on the Central Pacific Railway; starts in Sacramento, California, and joins the Union Pacific Railway in Utah in 1869 A.D 1500 2,220 Years Ago Archimedes, a Greek mathematician, discovers that the buoyant force equals the weight of the fluid displaced by an object (called Archimedes’ principle) 1600 c 1660 Robert Boyle of England describes what causes the pressure of gases to change 1700 Isaac Newton of England describes three laws of motion 1900 1800 1687 1877 Ernst Mach from Austria uses bullets to record the speed of sound; Mach becomes the reference for the speed of sound October 1947 1978 August 2005 Chuck Yeager—at Muroc Army Air Field (now Edwards Air Force Base, California)—is first to fly plane faster than speed of sound Speed boat sets record speed of 511.10 km/h on Lake Washington at Seattle, Washington Commander Eileen Collins and pilot James Kelly guide Space Shuttle Discovery in its 27,357.58 km/h glide from space to landing strip at Edwards Air Force Base 1920 1940 1960 1980 2000 1903 February 1962 1997 Wright Brothers fly first motorized airplane at Kitty Hawk, North Carolina John Glenn is first American to orbit Earth At the Black Rock speedway in Utah, Richard Noble’s jet race car is first to break the sound barrier on land (1227.93 km/h) June 1963 Valentina Tereshkova of the Soviet Union is the first woman to orbit Earth 42 43 Source: Unit 1, pp 42–43 Unit Review Reading on Your Own a listing of books recommended by the California State Board of Education UNIT Unit Test Choose the word or phrase that best answers the question Are you interested in learning more about motion, forces, buoyancy, and density? If so, check out these great books Science Fiction Project Pendulum, by Robert Silverberg, is the story of Earth’s first time travelers in 2016 One brother is carried back 95 million years in time and the other forward 95 million years in time The book records each brother’s observations in alternating chapters The content of this book is related to Science Standard 8.1 Nonfiction The Cartoon Guide to Physics, by Larry Gonick, provides concise explanations of physical principles with the help of amusing cartoons Topics include motion, Newton’s laws, momentum, energy, electricity, and magnetism The content of this book is related to Science Standard 8.1 Nonfiction Objects in Motion: Principles of Classical Mechanics, by Paul Fleisher, uses real-life Unit Test multiple-choice questions and writtenresponse questions that review the unit 2020 examples to make natural laws easy to understand The topics covered in this book include planetary motion, pendulums and falling objects, Newton’s three laws of motion, the law of universal gravitation, and conservation of momentum The content of this book is related to Science Standard 8.2 Narrative Nonfiction Dive! My Adventures in the Deep Frontier, by Sylvia Earle, is the author’s story of her investigation and exploration of the marine ecosystem Her experiences include tracking whales, living in an underwater laboratory, and helping design a deep-water submarine The content of this book is related to Science Standard 8.8 166 Unit • Reading on Your Own Which of these is not a vector? A force B distance C position D velocity Write your responses on a sheet of paper The graph below shows how Paul’s position changed as he walked to school 9^hiVcXZIgVkZaaZYdkZgI^bZ &'%% 1.d &%%% Edh^i^dcb 1863 1579 Francis Drake anchors the Golden Hind at Point Reyes just north of San Francisco, California, during first English voyage around the world Which type of force causes a sliding box to slow down and stop? A buoyant B compression C friction 2.e D gravity The forces applied to an object are N to the left and N to the right What is the net force on the object? A N to the right B N to the left C 13 N to the right 2.b D 13 N to the left In which situation are the forces acting on a bicycle balanced? A The bicycle speeds up as you pedal B The speed of the bicycle is constant as it turns C The bicycle slows down as it coasts D The bicycle moves in a straight line with con2.c stant speed as you pedal What is the density of a ring that has a mass of 11.5 g and a volume of 0.8 cm3? A 0.07 g/cm3 B 9.2 g/cm3 C 12.3 g/cm3 8.a D 14.4 g/cm3 -%% +%% )%% '%% % % &%% '%% (%% )%% *%% I^bZh Calculate Paul’s average speed over his entire 1.b trip Predict A baseball is traveling 40 km/h east toward a batter After the batter hits the ball, the ball is moving west at 40 km/h Did the ball 1.e accelerate? Support your reasoning Describe A rocket coasting toward Earth fires one of its rocket engines The force exerted on the ship is in the direction opposite to the rocket’s velocity How does the motion of the rocket 2.e change? Predict An object weighing 30 N is floating in water What is the weight of the water displaced 8.c by the object? Support your reasoning 10 Analyze why it is easier to lift an object that is under water than it is to lift the object when it is 8.c out of the water 11 Evaluate how the gravitational force between Earth and the space shuttle changes as the shuttle 2.g moves farther from Earth 12 Explain how a balloon filled with helium floats 8.c in the air Unit • Test 167 Source: Unit 1, pp 166–167 xxxiii Chapters /…iÊ Ê`i> The Big Idea is a sentence that describes what you will learn about in the chapter >ˆ˜Ê`i> The Main Ideas support the Big Idea Each lesson of the chapter has a Main Idea that describes the focus of the lesson Start-Up Activities Understanding the Atom /…iÊ Ê`i> What’s in the box? The early atomic scientists never saw atoms They came up with ideas about atoms by using scientific methods other than direct observation In this lab, you will study something you cannot see The current model of the atom includes protons, neutrons, and electrons Structure of an Atom Make the following Foldable to explain the structure of an atom STEP Fold a sheet of paper into thirds lengthwise Fold the top down about cm Procedure 3.a Atoms—Basic Units of Matter LESSON Complete a lab safety form Use wooden skewers to poke holes in your sealed box Predict what information you can find out by poking in the box >ˆ˜Ê`i> Matter is made of tiny particles called atoms Record your observations 3.a Discovering Parts of the Atom Predict what information you will learn by shaking the box >ˆ˜Ê`i> Scientists have put together a detailed model of atoms and their parts Try to guess what each object is 3.f, 7.b, 9.e Elements, Isotopes, and Ions—How Atoms Differ • Explain how you could answer those questions without opening the box LESSON Shake the box STEP Unfold and draw lines along all folds Label as shown NS 1ROTO &LECTRONS /EUTRON S Think About This • Identify what types of information you could guess by poking in the box LESSON 3.a Visualizing As you read this chapter, organize information about the parts of an atom Be sure to include where the part is located within the atom and the type of charge >ˆ˜Ê`i> Atoms of a particular element always have the same number of protons Things are not as they seem This computer-generated image of a helium atom shows what the inside of a balloon might look like Helium’s electron is more likely to be found in the blue area than in the other areas farther from the center -Vˆi˜ViÊÊ+PVSOBM Write a paragraph on what you know about the atom Visit ca8.msscience.com to: ▶ ▶ ▶ ▶ view explore Virtual Labs access content-related Web links take the Standards Check 170 171 Source: Chapter 4, pp 170–171 Launch Lab a short investigation that introduces the chapter’s subject xxxiv FoldablesTM Study Organizer an easy way to take notes as you read the chapter and a valuable tool for review Reading Skill This is a reading skill that you will practice throughout the chapter Lessons >ˆ˜Ê`i> The Big Idea is supported by Main Ideas Each lesson of the chapter has a Main Idea that describes the focus of the lesson Science Content Standards a listing of the California Science Content Standards that are covered within the lesson LESSON Science Content Standards 3.a Students know the structure of the atom and know it is composed of protons, neutrons, and electrons Reading Guide What You’ll Learn ▼ Describe the structure of the atom and where protons, neutrons, and electrons are located ▼ Compare the mass, size, and charge of the three basic particles of an atom ▼ Describe two observations that Dalton’s atomic theory supported Why It’s Important An understanding of the nature of the atom is the first step toward learning what the world is made of Vocabulary matter atom nucleus proton neutron electron Atoms—Basic Units of Matter >ˆ˜Ê`i> Matter is made of tiny particles called atoms Real-World Reading Connection How can you figure out what’s inside a wrapped box without opening it? Exploring the atom is like exploring that box Atoms can’t be observed directly with your eyes, so how have scientists learned about what’s inside them? What is the current atomic model? Would it surprise you to learn that the chair you are sitting on and the air you breathe are made up of the same thing? The world you live in is made of matter Matter is anything that has mass and takes up space Things you can see, such as your chair, and things you can’t see, such as air, are matter Matter is different from light, heat, and sound These are forms of energy Matter is made up of atoms An atom is a very small particle that makes up all matter Only recently have scientists been able to see the surface of an atom Inside the Atom In the early 1980s, a powerful new instrument called the atomic-force microscope was invented The atomic-force microscope can magnify an object up to one million times This magnification is great enough for the surfaces of individual atoms to be seen, as shown in Figure If further magnification were possible, you might be able to see inside an atom You probably would be surprised to find that most of the atom is empty space In this space, particles are moving No one has ever seen inside an atom, so how scientists know what atoms are made of? Review Vocabulary mass: a measure of the amount of matter in an object (p 11) a question that tests your reading comprehension Figure This atomic-force microscope image shows the surfaces of individual atoms and Caption Questions questions found throughout the lesson about important graphs, photos, or illustrations Lesson Review Looking Back at the Lesson The ancient Greeks taught that matter consists of tiny indivisible particles called atoms However, the Greeks couldn’t prove the existence of atoms It wasn’t until the seventeenth century that scientists began to look for evidence of the atom Their experiments demonstrated the law of conservation of mass and the law of definite proportions With these important ideas, Dalton described his atomic model Dalton’s model started the development of the modern model of the atom That model consists of even tinier particles called protons, neutrons, and electrons You’ll read more about these particles in Lesson LESSON Review 174 Chapter Standards Check Summarize Source: Chapter 4, Lesson 1, p 174 Summarize Use this exercise to help you create your own summary of the lesson’s content Create your own lesson summary as you write a script for a television news report Review the text after the red main headings and write one sentence about each These are the headlines of your broadcast Review the text and write 2–3 sentences about each blue subheading These sentences should tell who, what, when, where, and why information about each red heading Using Vocabulary Explain the difference between a neutron and a nucleus 3.a An atom contains equal numbers of _ and _ 3.a Understanding Main Ideas Which has no charge? A B C D 3.a electrons protons neutrons nucleus Mass Name the particles that make up an atom and tell where they are located 3.a Present your news report to other classmates alone or with a team Explain in your own words what is meant by the law of definite proportions 5.b Describe how Lavoisier was able to demonstrate the law of conservation of mass 5.b Self Check A series of questions to check your understanding of the lesson’s material Compare Copy and fill in the graphic organizer below to compare the mass and the volume of a proton with the mass and the volume of an electron 3.a Volume Proton Neutron Include descriptive details in your report, such as names of reporters and local places and events ELA8: LS 2.1 Show that the ratio of the number of atoms of hydrogen to the number of atoms of oxygen in the compound water is to 5.b Applying Science Design an experiment that confirms the law of conservation of mass 5.b 10 Assess the reasons why Dalton, not Democritus, is credited with being the “Father of the Atom.” 3.a Science nline For more practice, visit Standards Check at ca8.msscience.com Lesson • Atoms—Basic Units of Matter 179 Source: Chapter 4, Lesson 1, p 179 xxxv Hands-On Science Table Summary of Rutherford’s Conclusions How electrons move? Procedure Complete a lab safety form Draw a straight line down the center of a 10-cm ؋ 10-cm block of foam with a ruler Break 20 toothpicks in half Poke the halves into the foam so they are like the nucleus of an atom Use round, dried peas as electrons Aim and flick the peas down the center line on the block Make a diagram to show where the electrons came out Use a protractor to measure the angle the electrons made compared to the center line, which is the path they would have followed if they did not hit any atoms Evidence An atom is mostly empty space The charged particles that bounced back could not have been knocked off course unless they had hit a mass much larger than their own Most of the mass of an atom is concentrated in a small space within the atom A few of the alpha particles bounced directly back The positive charge is concentrated in a small space within an atom Rutherford’s Atomic Model Using the observations of his students, Rutherford drew some conclusions, which are summarized in Table Most of the alpha particles passed directly through the gold atoms For this to happen, the atoms must have contained mostly empty space Because some alpha particles were strongly deflected from their paths, those particles must have come near a large positive charge Very few alpha particles were bounced completely backward Those particles that did bounce back must have collided with a mass having a large positive charge Drawing on these conclusions, Rutherford revised Thomson’s model of the atom Figure 13 shows Rutherford’s new atomic model Notice that most of the volume of an atom is empty space At the center is the nucleus An atom’s electrons move very fast in the empty space surrounding the nucleus Thinking about Rutherford’s results, American poet Robert Frost wrote a very short poem, The Secret Sits “We dance round in a ring and suppose, But the Secret sits in the middle and knows.” Analysis Describe how your arrangement of toothpicks was like the nuclei of atoms in a block of metal Why did the toothpicks represent just the nuclei instead of the whole atoms? Describe problems you had with this experiment MiniLab These investigations emphasize the lesson’s content MiniLabs are located in either a margin, like the one shown here, or on a full page The California Science Content Standards that correlate to the material are listed Conclusion Most of the alpha particles passed right through the gold foil How atoms differ? What you think sits in the middle? What dances round in a ring? Each element is made up of atoms with a certain number of particles The periodic table tells you how many protons and electrons are in atoms of each type Nucleus Figure 13 Rutherford’s atom included a positively charged nucleus Electrons moved in the space around the nucleus Data Collection Copy the table twice in your Science Journal In your first copy, 3.a write the symbol for each element in the center of its square Use the periodic table 186 Chapter • Understanding the Atom Write the mass number at the top right corner Write the number of neutrons in the bottom right corner In the second table, draw a diagram of each element Write the Rutherford’s Model M646-04C-MSS02 number of protons and neutrons inside a circle to show the nucleus Put the correct number of electrons for each element in rings in 1, 2, or rings outside the nucleus Source: Chapter 4, p 186 DataLab These investigations emphasize the lesson’s content by using mathematical analysis DataLabs are located in either a margin or on a full page, as shown here The California Science Content Standards and the California Mathematics Content Standards that correlate to the material are listed 10 11 12 13 14 15 16 17 18 Data Analysis Graph the atomic mass versus atomic number for your elements Explain how atomic mass varies as atomic number increases Science Content Standards 3.a Students know the structure of the atom and know it is composed of protons, neutrons, and electrons 3.f Students know how to use the periodic table to identify elements in simple compounds 9.e Construct appropriate graphs from data and develop quantitative statements about the relationships between variables 203 Source: Chapter 4, p 203 Analyze and Conclude Model and Invent: Build an Atom Materials dried peas small balloons medium balloons large balloons craft wire small pompoms jelly beans glue Problem You have learned about the people who developed a picture of what atoms look like and you have learned the parts of an atom Now, create an atom Use craft materials to design and produce your own model of an atom Collect Data and Make Observations Select Your Model Read and complete a lab safety form Choose an element Draw an atomic structure diagram for that element in your Science Journal List everything you know about protons, neutrons, electrons, and their behavior Plan Your Model How will you model the atom? Decide what materials you will Safety Precautions Science Content Standards 3.a Students know the structure of the atom and know it is composed of protons, neutrons, and electrons use for the atom How will you arrange the electrons outside the nucleus? Do you want to put electrons on wire or in balloon clouds? What type of objects will you use to show protons, electrons, and neutrons? Make sure your teacher has approved your model before you proceed Communicate 3CIENCE ELA8: LS 2.4 Peer Review With your classmates, compare and contrast your models Discuss the best features of each model and ways that each might be improved Vote on which model does the best job representing: • particles of the nucleus • electrons • size of the nucleus • distance of electrons from the nucleus • movement of electrons • electron levels Be prepared to defend your vote for each category Can you explain why you voted the way you did? Build Your Model Create your atomic model Show and discuss your model with your classmates 204 Source: Chapter 4, pp 204–205 xxxvi Lab Full-length investigations emphasize the chapter’s content Included are Labs or Design Your Own Labs The California Science Content Standards that correlate to the material are listed Describe how you represented the nucleus in your model Do you think this worked well? Describe how you represented electrons in your model Explain how your model mimics how electrons behave Write a paragraph describing two of your classmates’ models What did you like about their models? What you think they could have done better? Explain how your model would work if you decided to make a smaller atom Would another model work better? What if you tried to make a larger atom? Infer How the mass and distance ratios of your model compare with reality? Error Analysis What could have been better about your model? Explain in detail how you could improve it 205 Special Features 6ae]VeVgi^XaZ hdjgXZ EVgi^XaZhWdjcXZY WVX`lVgY EVgi^XaZhl^i]a^iiaZ dgcdYZ[aZXi^dc To see animation of Rutherford’s experiment, visit ca8.msscience.com 9ZiZXidghXgZZc :aZXigdc