Foundations of Chemistry

Transcription

1 Name Foundations of Chemistry What is matter, and how does it change? Date Before You Read Before you read the chapter, think about what you know about matter and how it changes Record three things that you already know about matter in the first column Then write three things that you would like to learn about matter in the second column Complete the final column of the chart when you have finished this chapter K What I Know W What I Want to Learn L What I Learned Copyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc Chapter Vocabulary Lesson 1 Lesson 2 Lesson 3 Lesson 4 NEW matter atom substance element compound mixture heterogeneous mixture homogeneous mixture dissolve ACADEMIC unique NEW physical property mass density solubility REVIEW property NEW physical change NEW chemical property chemical change concentration A Lesson Content Vocabulary page for each lesson is provided in the Chapter Resources Files Foundations of Chemistry 65

2 Lesson 1 Classifying Matter Scan Lesson 1 Read the lesson titles and bold words Look at the pictures Identify three facts you discovered about matter Record your facts in your Science Journal Understanding Matter 231 Sample examples are shown Organize information about matter 2 characteristics has mass takes up space Matter Smallest particle: atom Examples Matter metal wood plastic clouds Not matter sound light forces energy Atoms Identify and describe the parts of an atom proton positively charged particle in the nucleus nucleus the protons and neutrons in the atom s center neutron particle with no charge in the nucleus electrons negatively charged particles moving in the electron cloud Relate the number of protons in the nucleus of an atom to the properties of matter The number of protons determines the type of atom and the Copyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc properties in the matter made up of that type of atom 66 Foundations of Chemistry

3 Lesson 1 Classifying Matter (continued) Substances 233 Define substance, and identify two examples Definition: matter with a composition that is always the same Examples: elements and compounds 233 Examine how atoms of elements differ Circle the characteristic that gives each type of atom its unique properties Example Aluminum Oxygen Is it a substance? yes yes Is it an element? How many protons are in its nucleus? How do its atoms usually exist? yes yes 13 8 individually in pairs 234 Differentiate elements from compounds Copyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc Element a substance that consists of just one type of atom Interpret the chemical formula This means a carbon atom CO 2 Compound a substance containing atoms of two or more different elements chemically bonded together This means an oxygen atom This means that there are two oxygen atoms for every one carbon atom Relate properties of a compound to the properties of the elements of which it is made A compound often has different properties from the individual elements that compose it Foundations of Chemistry 67

4 Lesson 1 Classifying Matter (continued) Mixtures 235 Organize information about mixtures Definition: matter that can vary in composition Mixture Combination of: two or more substances that are physically blended Heterogeneous: Substances are not evenly mixed Types Homogeneous: Individual substances are evenly mixed 235 Complete the statement to describe how a substance dissolves In a solution, the solvent is the substance present in the largest amount; the solutes are all the other substances that dissolve in the solvent Compounds v Solutions 236 Explain whether a chemical formula can describe a solution A chemical formula cannot be use to describe a solution Summarizing Matter 236 because a solution s composition can vary Order the classifications of matter Use the words in the box to make a sequence that is true atoms can make up can make up elements substances can make up can make up compounds elements mixtures substances compounds mixtures Copyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc Analyze It Evaluate whether the following statement is true or false, and explain why: All solutions are mixtures The statement is true A solution is the same thing as a homogeneous mixture 68 Foundations of Chemistry

5 Lesson 2 Physical Properties Predict three facts that will be discussed in Lesson 2 after reading the headings Record your predictions in your Science Journal Physical Properties 240 Sample examples are shown 241 Define physical property, and give two examples Definition: a characteristic of matter that you can observe or measure without changing the identity of the matter 1 mass 2 state Differentiate states of matter State Arrangement of Particles Motion of Particles Solid very close together can only vibrate back and forth Liquid slightly farther apart than in a solid can slide past one another Copyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc 242 Gas Contrast three size-dependent physical properties Circle the measurement that changes with location Property Mass Weight spread out to fill a closed container move very quickly Description the amount of matter in an object the pull of gravity on matter 243 Volume the amount of space something takes up Foundations of Chemistry 69

6 Lesson 2 Physical Properties (continued) Describe four size-independent physical properties 243 Melting and boiling point: the temperatures at which matter changes state Density: the mass per unit volume of a substance Size-Independent Properties 244 Conductivity: the ability of matter to conduct electric current Solubility: the ability of one substance to dissolve in another 245 Sample answers are shown Students might identify and describe other properties, including melting point and state of matter Identify and describe three physical properties that can be used to separate mixtures Property Magnetism Boiling point Density How it can be used to separate a mixture A magnet will attract iron from a mixture of materials Each part of a mixture will boil at a different temperature Objects with greater density will sink in matter with less density Synthesize It Look again at the picture of the man panning for gold on the first page of Lesson 2 Another method he could use to separate the mixture would be to sift the sediment through a screen What physical property affects how sifting separates a mixture? Would this be as effective for finding gold as panning? Accept all reasonable responses Sample answer: Sifting relies on the property of volume, or the space taken up by each particle in the sediment This would probably not be the best way to separate gold out of the mixture Tiny (but still valuable) pieces Copyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc of gold would pass through the screen while larger, worthless sand grains and pebbles would be trapped 70 Foundations of Chemistry

7 Lesson 3 Physical Changes Skim Lesson 3 in your book Read the headings and look at the photos and illustrations Identify three things you want to learn more about as you read the lesson Record your ideas in your Science Journal Physical Changes 249 Characterize physical changes in matter Physical Changes in Matter What can change? size shape form state What does not change? matter s identity 249 Explain one way that you changed the size or shape of matter as you made and ate your breakfast Sample answer: I changed the shape of matter when I poured orange juice from the container into a glass Copyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc 250 Sequence changes in the state of matter with the continuous addition of thermal energy Thermal energy is added to a solid; particles move faster ; temperature increases Particles overcome attractive forces; melting occurs; temperature remains constant Entire solid becomes liquid ; particles move faster; temperature increases Particles overcome attractive forces; boiling occurs; temperature remains constant Entire liquid becomes gas ; temperature increases Foundations of Chemistry 71

8 Lesson 3 Physical Changes (continued) 251 Identify the opposites of selected physical changes melting boiling sublimation freezing condensation deposition 252 Explain dissolving, and express how boiling can reverse the process in the example of salt water Dissolving is a physical change that mixes the salt evenly throughout the water Boiling the solution changes the liquid water to water vapor, leaving the salt behind Conservation of Mass 252 Model conservation of mass in a labeled drawing that illustrates a mixture Accept all reasonable responses Student drawings should show that the mass of the final mixture equals the combined masses of the substances that make it up Connect It Look at this paper in front of you and the pen or pencil in your hand Describe the physical change and conservation of mass you observed in those items as you completed the exercises on this page Accept all reasonable responses Sample answer: When I wrote my answers, it moved graphite from the pencil to the paper The shape of the graphite changed, but identity of the materials did not The total mass stayed the same, too; now some of Copyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc the graphite s mass is just spread out in the lines on the paper instead of contained where it used to be in the pencil 72 Foundations of Chemistry

9 Lesson 4 Chemical Properties and Changes Predict three facts that will be discussed in Lesson 4 after reading the headings Record your predictions in your Science Journal Chemical Properties 256 Sample examples are shown Students might note others Comparing Properties 256 Define chemical property, and give two examples Definition: a characteristic of matter that can be observed as it changes to a different type of matter 1 2 ability to burn ability to rust Contrast physical and chemical properties using the example of a wood log Properties of a Wood Log Physical Observable: rounded heavy Chemical ability to burn ability to rot Copyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc Chemical Changes 257 Signs of Chemical Change 257 Measurable: mass volume Characterize chemical change Substances that make up matter change into New substances with new chemical properties new Identify some signs of a chemical change Sign: bubbles Sign: color change Chemical Change physical properties Sign: energy change Sign: odor change Foundations of Chemistry 73

10 Lesson 4 Chemical Properties and Changes (continued) 257 Describe what constitutes proof of a chemical change formation of a new substance Explaining Chemical Reactions 258 Order the events that occur in a chemical reaction Atoms are bonded and form particles of substances together As particles collide, bonds break and atoms separate Atoms rearrange and bond with different atoms in new combinations New substances form 258 Describe the parts of a chemical equation, and then tell why these equations are useful 259 Reactants: substances present before the reaction takes place yield Products: new substances present after a reaction Chemical equations are useful because they show the chemical formula of each substance in a reaction Express how a balanced chemical equation illustrates conservation of mass It shows the same numbers of atoms of each element on both sides of the equation Because the total number of Copyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc 74 Foundations of Chemistry atoms is the same before and after the reaction, the total mass is the same before and after the reaction

11 Lesson 4 Chemical Properties and Changes (continued) 259 Assess the role of coefficients in chemical equations Coefficients change the amount of reactants and products present do not change the identity of substances The Rate of Chemical Reactions 260 Factor Explain how factors affect the rate of chemical reactions Effect on Reaction Speed Temperature Higher temperature makes particles move faster and thus speeds a reaction Concentration Increased concentration provides more particles and thus speeds a reaction Copyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc Chemistry 260 Students might also cite how properties can change Surface area Paraphrase two things you need to know about matter in order to understand chemistry 1 2 how the arrangement of atoms determines different types of matter Increased surface area exposes more particles and thus speeds a reaction the differences between chemical and physical properties Synthesize It Describe two chemical changes that have happened in your home this week Accept all reasonable responses Sample answer: Chemical change occurred when we burned wood in the fireplace last night Also, there was a potato decomposing in the bottom drawer of the refrigerator yesterday Its bad smell indicated a chemical change Foundations of Chemistry 75

12 Review Chapter Wrap-Up Foundations of Chemistry Now that you have read the chapter, think about what you have learned Complete the final column in the chart on the first page of the chapter Use this checklist to help you study Complete your Foldables Chapter Project Study your Science Notebook on this chapter Study the definitions of vocabulary words Reread the chapter, and review the charts, graphs, and illustrations Review the Understanding Key Concepts at the end of each lesson Look over the Chapter Review at the end of the chapter Summarize It Reread the chapter Big Idea and the lesson Key Concepts Summarize why it is necessary to have these ways of classifying and describing matter and its changes Accept all reasonable responses Sample answer: The roughly 115 elements shown in the periodic table can combine physically and chemically in countless ways The original chemical and physical properties of those elements can also be altered in countless ways by the different methods through which matter is combined This is a lot of information to keep track of! Categorizing matter by properties and changes helps us understand how matter behaves Copyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc Challenge Find evidence of a chemical reaction that has occurred at your home Do research to learn about the matter involved the reactants and the products Write a balanced chemical equation for the reaction, and explain the equation to your class 76 Foundations of Chemistry