2.1 Classifying Matter

Reading StrategySummarizing Copy the diagram below. Asyou read, complete the classification of matter.

Key ConceptsWhy are elements andcompounds classified aspure substances?

How do mixtures differfrom pure substances?

What is the maindifference amongsolutions, suspensions,and colloids?

Vocabulary◆ pure substance◆ element◆ atom◆ compound◆ heterogeneous

mixture◆ homogeneous

mixture◆ solution◆ suspension◆ colloid

Each piece of clothing sold has a care label, which lists recommendedcleaning methods for the clothing. For a sweater, the instructionsmight say to machine wash the sweater using a gentle cycle, and thentumble dry at a low temperature. They might say to hand wash thesweater in cold water and lay the sweater flat to dry. The label mighteven say, “Dry clean only.”

Why is it necessary to put care instructions on a label? The samecleaning method will not work for all materials. For example, a shirtmade from 100 percent cotton may need to be ironed after washing.But a shirt made from a cotton and polyester blend may come out ofthe dryer wrinkle free. A wool jacket often needs to be dry cleanedbecause wool can shrink when washed in water.

The tendency to wrinkle when washed is a property of cotton.The tendency not to wrinkle when washed is a property of poly-ester. The tendency to shrink when washed is a property of wool.Cotton, wool, and polyester have different properties because

they have different compositions. The word compositioncomes from a Latin word meaning “a putting together,” orthe combining of parts into a whole. Based on their com-positions, materials can be divided into pure substancesand mixtures.

Matter

a. ? Mixture

Element b. ? c. ? d. ?

Figure 1 You can use the care labels on clothing tosort laundry into batches for cleaning. The carelabel shown is for a wool sweater that needs to bedry cleaned or washed by hand.

38 Chapter 2

38 Chapter 2

FOCUS

Objectives2.1.1 Classify pure substances as

elements or compounds.2.1.2 Describe the characteristics of

an element and the symbolsused to identify elements.

2.1.3 Describe the characteristics ofa compound.

2.1.4 Distinguish pure substancesfrom mixtures.

2.1.5 Classify mixtures as hetero-geneous or homogeneous.

2.1.6 Classify mixtures as solutions,suspensions, or colloids.

Build VocabularyParaphrasing To help studentsunderstand the definitions of vocabu-lary terms, you may replace less familiarwords in a definition with a more familiarword or phrase. For example, you canreplace distributed in the definition of ahomogeneous mixture with “spreadout,” or shattering in the definition ofmalleability with “breaking into pieces.”

Reading Strategya. Substance b. Compoundc. and d. Homogeneous mixture orheterogeneous mixture

INSTRUCT

Some students may associate the termmaterial exclusively with solids becausethey can see and hold solid materials.They may have difficulty recognizingthat liquids and gases are also matter.Challenge this misconception by point-ing to the Materials list for the lab onp. 60 and asking students to identifythe liquids.Verbal

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Reading Focus

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Section 2.1

Print• Reading and Study Workbook With

Math Support, Section 2.1• Math Skills and Problem Solving

Workbook, Section 2.1• Transparencies, Chapter Pretest and

Section 2.1

Technology• Interactive Textbook, Section 2.1• Presentation Pro CD-ROM, Chapter Pretest

and Section 2.1• Go Online, NSTA SciLinks, Mixtures

Section Resources

Pure SubstancesMatter that always has exactly the same composition is classified as apure substance, or simply a substance. Table salt and table sugar aretwo examples of pure substances. Every pinch of salt tastes equallysalty. Every spoonful of sugar tastes equally sweet. Every sample ofa given substance has the same properties because a substance hasa fixed, uniform composition. Substances can be classified into twocategories—elements and compounds.

ElementsAlthough there are millions of known substances, there are only about100 elements. An element is a substance that cannot be broken downinto simpler substances. Imagine cutting a copper wire into smallerand smaller pieces. Eventually you would end up with extremely tinyparticles called copper atoms. An atom is the smallest particle of anelement. An element has a fixed composition because it containsonly one type of atom.

No two elements contain the same type of atom. In Chapter 4, youwill find out more about atoms, including how the atoms of one ele-ment differ from the atoms of every other element.

Examples of Elements At room temperature (20°C, or 68°F),most elements are solids, including the elements aluminum andcarbon. You have seen aluminum foil used to wrap food. Most softdrink cans are made from aluminum. Carbon is the main element inthe marks you make with a pencil on a piece of paper. Some elementsare gases at room temperature. The elements oxygen and nitrogen arethe main gases in the air you breathe. Only two elements are liquids atroom temperature, bromine and mercury, both of which are extremelypoisonous. Figure 2 shows four elements and their symbols.

Figure 2 Aluminum, carbon, andgold are elements that you cansee in common objects, such ascans, pencils, and rings. Mixturescontaining iodine are used toprevent and treat infections.Analyzing Data Which of theseelements has a symbol that is notrelated to its name in English?

Properties of Matter 39

Aluminum (Al)

Carbon (C)

Iodine (I)

Gold (Au)

Pure SubstancesFYISamples of pure substances almostalways contain impurities, some that are unintentional, some intentional. For example, table salt is not puresodium chloride. It contains between0.006% and 0.01% potassium iodide.

ElementsFYISometimes an atom is defined as “thesmallest particle of an element that hasthe properties of the element.” However,an atom of copper has none of the prop-erties associated with bulk copper, suchas malleability, ductility, or density.

Build Science SkillsObserving Have students look at theelements in Figure 2. Ask, What aresome characteristics of the elements in Figure 2? (Gold is yellow and shiny.Aluminum is gray and shiny. Carbon is dulland black. Iodine is a dark purple solid.)Follow up on their observations by askingstudents to hypothesize about why theiodine sample is in a closed container. (Atroom temperature, iodine evaporates andforms a purple gas, which is visible in thecontainer. The gas is poisonous.)Visual

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Properties of Matter 39

Customize for English Language Learners

Sharing ExperiencesEncourage multilingual students to describewhat a particular element is called in theirnative language. This exercise will be mostuseful for those elements that have been

known for centuries or millennia. (Examplesinclude carbon, mercury, sulfur, iron, copper,tin, zinc, silver, gold, and lead.) Use thisinformation as a springboard for discussing the element names given in the text.

Answer to . . .

Figure 2 Gold

Symbols for Elements In 1813, Jöns Berzelius, a Swedishchemist, suggested that chemists use symbols to represent elements.Many of the symbols he assigned to elements are still used. Each symbolhas either one or two letters. The first letter is always capitalized. If thereis a second letter, it is not capitalized.

It is easy to see why C and Al are used to represent carbon and alu-minum. But why does gold have the symbol Au? The symbols thatBerzelius chose were based on the Latin names of the elements. TheLatin name for gold is aurum.

The symbols allow scientists who speak different languages to com-municate without confusion. For example, nitrogen is known as azotein France, as stickstoff in Germany, and as nitrógeno in Mexico. But sci-entists who speak English, French, German, and Spanish all agree thatthe symbol for the element nitrogen is N.

Sometimes an element’s name contains a clue to its properties. Forexample, the name hydrogen comes from the Greek words hydro andgenes, meaning “water” and “forming.”

CompoundsWater is composed of the elements hydrogen and oxygen. When elec-tricity passes through water, bubbles of oxygen and hydrogen gas formand rise to the surface of the water. If the gases are collected in a con-tainer and a flame is brought near the mixture, the hydrogen andoxygen react and form water. Water is classified as a compound. Acompound is a substance that is made from two or more simpler sub-stances and can be broken down into those simpler substances. Thesimpler substances are either elements or other compounds.

The properties of a compound differ from those of the substancesfrom which it is made. For example, oxygen and hydrogen are gases atroom temperature, but water is a liquid. Hydrogen can fuel a fire, andoxygen can keep a fire burning, but water does not burn or help othersubstances to burn. In fact, water is one of the substances commonlyused to put out fires.

Figure 3 shows another example of how properties change whenelements join and form compounds. Silicon dioxide is a compoundfound in most light-colored grains of sand. It is a colorless, transparentsolid. Yet, silicon dioxide is made from a colorless gas (oxygen) and agray solid (silicon). Silicon is used to make chips for computers.

A compound always contains two or more elements joined ina fixed proportion. For example, in silicon dioxide, there are always twooxygen atoms for each silicon atom. (Di- means “two.”) In water, thereare always two hydrogen atoms for each oxygen atom.

What happens if electricity passes through water?

40 Chapter 2

Silicon

Oxygen

Silicondioxide

Figure 3 Elements have differentproperties than their compounds.Silicon is a gray solid and oxygen isa colorless gas, which can bestored in a metal tank. Silicon andoxygen combine to form silicondioxide—a colorless, transparentsolid found in most grains of sand.

40 Chapter 2

IntegrateLanguage ArtsHave students research and explain theorigin of element symbols (other thanAu) that are not abbreviations for ele-ment names in English. Examples includesilver (Ag), lead (Pb), tin (Sn), antimony(Sb), and mercury (Hg).Verbal, Portfolio

CompoundsFYIWhen the terms element, atom, com-pound, and molecule are defined in anintroductory section, the definition of a molecule is often both too broad and too narrow. Molecules are not thesmallest particle of all compounds, and many elements exist in nature asmolecules. For this reason, in this text,the formal definition of molecule doesnot appear until Chapter 6, the chapteron bonding, where it can be definedaccurately. (The term molecule isintroduced informally in Section 3.3when water molecules are described.)

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Section 2.1 (continued)

Electrolysis of Water Early chemists were able to use heat to break down manycompounds into their constituent elements.Because water cannot be decomposed by thismethod, water was classified as an elementuntil chemists were able to use electric current

to break down water into hydrogen andoxygen. (The decomposition of water intohydrogen and oxygen will not occur unlessions are added to the water because there arenot enough ions in pure water to conduct an electric current.)

Facts and Figures

Properties of Matter 41

MixturesSuppose you are making salsa using the ingredients shown in Figure 4.You have a choice. You can use exactly the amounts listed in the recipe,or you can adjust the ingredients according to your own taste. Youmight have to prepare the recipe a few times before deciding if youhave just the right amount of each ingredient.

Mixtures tend to retain some of the properties of their individualsubstances. But the properties of a mixture are less constant than theproperties of a substance. The properties of a mixture can varybecause the composition of a mixture is not fixed. The type of pepperand the quantity of pepper used in a salsa recipe determine the “hot-ness” of a batch of salsa. Chili peppers contain a compound calledcapsaicin (kap SAY uh sin) that can cause a burning sensation in yourmouth. The amount of capsaicin varies among types of peppers.Cayenne peppers, for example, contain more capsaicin than dojalapeño peppers.

No matter how well you stir a batch of salsa, the ingredientswill not be evenly distributed. There may, for example, bemore onion in one portion of the salsa than another.Mixtures can be classified by how well the parts of the mix-ture are distributed throughout the mixture.

Heterogeneous Mixtures If you look at a handfulof sand from a beach, the sand appears to be all the samematerial. However, if you use a hand lens, you will notice that thesample of sand is not the same throughout. Figure 5 shows that grainsof sand vary in size. Also, some grains are light in color and some aredark. Sand is an example of a heterogeneous mixture. Heterogeneous(het uh roh GEE nee us) comes from the Greek words hetero and genus,meaning “different” and “kind.” In a heterogeneous mixture, the partsof the mixture are noticeably different from one another.

Figure 4 The ingredients shownare used to make one kind ofsalsa, which is an example of aheterogeneous mixture.

Figure 5 Sand is a hetero-geneous mixture. The spoonis stainless steel, which is ahomogeneous mixture.Interpreting PhotographsExplain how viewing sandthrough a hand lens helps showthat sand is a heterogeneousmixture.

• 4 or 5 plum tomatoes

• 3–5 fresh Serrano

chili peppers

• 12 sprigs of cilantro

• large garlic clove

• small white onion

• 1 teaspoons

fresh lime juice

• teaspoon

salt

Salsa

12

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MixturesBuild Reading LiteracyCompare and Contrast Refer to page 226D in Chapter 8, which pro-vides the guidelines for comparing and contrasting.

Have students read pp. 41–44 and gatherinformation on different classifications ofmixtures. Then, have students create achart that compares and contrasts eachtype of mixture.Visual

IntegratingLanguage ArtsHave students consider the differencebetween hot food (as in warm versuscold) and hot food (as in spicy versusmild). Encourage students to suggestexamples of dishes other than salsa that are hot in the second, spicy sense.Some students may want to record afamily recipe for a “hot” dish. Havethem identify the ingredient(s) that can be varied to control the “hotness”of the mixture. Logical

Build Science SkillsObserving Have students look atsamples of sand with a hand lens. Explainthat the composition of sand can varyfrom beach to beach because the rocksand shells from which sand forms havedifferent compositions. Ask, How canyou tell that sand is a heterogeneousmixture? (The grains of sand vary in colorand size.) (A sample of sand that containsonly ground-up shells would probably beclassified as homogeneous.) Visual

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Properties of Matter 41

Capsaicinoid Content Capsaicin (8-methyl-N-vanillyl-6-nonenamide) is the most abundantof a group of compounds called capsaicinoids.These compounds are found in the seeds andmembranes of chili peppers. When they areingested, they affect pain receptors in themouth and throat. Because capsaicin is an oil,and oil and water do not mix, drinking waterspreads the oil to more parts of the mouth and increases the burning sensation.

The capsaicinoid content of a pepper ismeasured in Scoville units. Wilbur Scovilledeveloped the method for measuring the“hotness” of chili peppers in 1912. He mixedground chilies with a sugar and water solutionand diluted the mixture until tasters no longerreported a burning sensation. The greater thedilution needed, the higher the assignednumber of Scoville units. Fifteen Scoville unitsis equivalent to one part per million.

Facts and Figures

Answer to . . .

Figure 5 More details are visible in the magnified sand, making it easier to observe the different parts of the mixture.

Bubbles of oxygen andhydrogen form and rise

to the surface of the water.

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Homogeneous Mixtures If you collect water from both theshallow end and the deep end of a swimming pool, the water sampleswill appear the same. The water in a swimming pool is a homogeneous(hoh moh GEE nee us) mixture of water and substances that dissolve inwater. In a homogeneous mixture, the substances are so evenly dis-tributed that it is difficult to distinguish one substance in the mixturefrom another. A homogeneous mixture appears to contain only onesubstance. The serving spoon in Figure 5 is made of stainless steel—ahomogeneous mixture of iron, chromium, and nickel.

Solutions, Suspensions, and ColloidsIt isn’t always easy to tell a homogeneous mixture from a heterogeneousmixture.You may need to observe the properties of a mixture before youdecide. The size of the particles in a mixture has an effect on the prop-erties of the mixture. Based on the size of its largest particles, amixture can be classified as a solution, a suspension, or a colloid.

Solutions If you place a spoonful of sugar in a glass of hot waterand stir, the sugar dissolves in the water. The result is a homogeneousmixture of sugar and water. When substances dissolve and form ahomogeneous mixture, the mixture that forms is called a solution.The windshield wiper fluid in Figure 6 is a solution. So is tap water.

Do the Contents of Two Cansof Mixed Nuts Meet FDARegulations?

The Food and Drug Administration (FDA) has twomain areas of concern about food. First, and mostimportant, the FDA ensures that food sold in theUnited States is safe to eat. Second, the FDAensures that the information on a food labelaccurately describes a food product.

What can you assume when you see the label“mixed nuts” on a can of nuts? According to theFDA regulations, a can labeled mixed nuts mustcontain at least four types of shelled nuts otherthan peanuts. The mass of each type of nut mustbe not less than 2 percent of the total mass andnot more than 80 percent of the total mass.

1. Comparing and Contrasting How arethe two brands of mixed nuts alike? Howare they different?

2. Calculating What is the percent by mass ofeach type of nut in each can?

3. Drawing Conclusions Do the contents ofeach can meet the FDA regulations? Explain.

4. Inferring On the Brand A label, the nutsare listed in this order: peanuts, Brazil nuts,almonds, cashews, pecans, and hazelnuts.What do you think determines the order?

Type of Nut

Peanut

Almond

Brazil nut

Cashew

Hazelnut

Pecan

152.39 g

47.02 g

57.88 g

46.20 g

19.90 g

21.40 g

Mass inBrand B

191.96 g

31.18 g

19.60 g

73.78 g

16.90 g

16.90 g

Contents of Two Cans of Mixed NutsMass inBrand A

For: Links on mixtures

Visit: www.SciLinks.org

Web Code: ccn-1021

Do the Contents of TwoCans of Mixed NutsMeet FDA Regulations?Answers1. Both brands contain the same sixtypes of nuts, but the amount of eachtype of nut varies. 2. There are 344.79 g in Brand A and350.32 g in Brand B. The percents bymass in Brand A are: 44.2% peanuts,13.64% almonds, 16.79% Brazil nuts,13.4% cashews, 5.77% hazelnuts, and 6.21% pecans. The percents bymass in Brand B are: 54.8% peanuts,8.90% almonds, 5.59% Brazil nuts,21.06% cashews, 4.82% hazelnuts, and4.82% pecans.3. Yes. Both brands contain more thanfour types of nuts other than peanuts.The percent of each nut by mass is withinthe 2% to 80% range. 4. The ingredients are listed in order bytotal mass. The ingredient with thelargest total mass is listed first.

For Extra HelpHave students answer Question 3 by cal-culating 2% and 80% of each total massand checking to see if any of the massesfall outside that range. Logical

Solutions, Suspensions, and ColloidsFYIMany alloys are not true solutions.Sterling silver, a mixture of silver andcopper, is an example. Silver and copperare completely soluble in all proportionswhen molten. However, solid sterlingsilver is a two-phase alloy with pocketsof silver and pockets of a 71.9% silverand 28.1% copper mixture.

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Regulatory Agencies Responsibility forprotecting the food supply is shared amongthe FDA, the Department of Agriculture, andthe EPA, which regulates pesticides. Food that is adulterated or mislabeled may bevoluntarily destroyed or recalled, or seized by court order. The FDA is responsible forestablishing standards for identity, quality, and fill of container. If standards have been

set for a product, such as mixed nuts, theproduct must comply with those standards.Food labels must include a statement ofidentity (usual or common name), the netquantity of the contents, the name and place of business of the supplier, and a list of ingredients in descending order bymass. The goal is to have honest andinformative labels.

Facts and Figures

Download a worksheet onmixtures for students to complete,and find additional teacher supportfrom NSTA SciLinks.

42 Chapter 2

Liquid solutions are easy to recognize. They do not separate intodistinct layers over time. If you pour a liquid solution through a filter,none of the substances in the solution are trapped in the filter. You cansee through solutions that are liquids because light passes throughthem without being scattered in all directions. These three propertiesof liquid solutions can be traced to the size of the particles in a solu-tion. The particles in a solution are too small to settle out of thesolution, be trapped by a filter, or scatter light.

Suspensions Have you ever seen the instruction “Shake wellbefore using” on a bottle? This instruction is a clue that the material inthe bottle is a suspension. A suspension is a heterogeneous mixturethat separates into layers over time. For example, if you shake up a con-tainer of sand and water, the sand mixes with the water and forms asuspension. Over time, the suspended particles of sand settle to thebottom of the container.

You could use a filter to separate the sand from the water. The waterwould pass through the filter, but the sand would remain in the filterpaper. Suspended particles settle out of a mixture or are trapped by afilter because they are larger than the particles in a solution. Theworker in Figure 7 is using a mask to filter out particles of plastic foamthat are suspended in air. Because larger particles can scatter light in alldirections, suspensions are cloudy.

What happens to suspended particles over time?

Figure 6 The liquids shown representthree categories of mixtures. A Windshieldwiper fluid is a solution. B Muddy watercollected from a swamp is a suspension. C Milk is a colloid. Comparing and Contrasting Based onappearance, how are a solution and acolloid similar?

Figure 7 When a surfboard issanded, particles of plasticbecome suspended in air. Theworker wears a mask to keepfrom breathing in the particles.

Properties of Matter 43

B

AA

CC

Transmission VersusScatteringPurpose Students observe light passthrough different mixtures.

Materials 2 beakers, water, iodinesolution, table salt, stirring rods, milk,fish tank, flashlight, white paper

Procedure Demonstrate that asolution can have color and still transmitlight. Fill two beakers halfway withwater. Add a small amount of iodinesolution to one beaker and stir. Addtable salt to the second beaker. Askstudents to describe the color of eachmixture and state whether it is clear. Demonstrate transmission of light versusscattering. Fill the tank with water. Turnoff the lights. Shine a flashlight throughthe tank so that it lights up the whitepaper placed behind the tank. Addsome milk to the water and stir. Shinethe light through the tank again. (Thesebehaviors of light are discussed in detailin Section 18.3.)

Expected Outcome Although the salt solution is colorless and the iodinesolution is colored, both transmit light.Light passes through the water in thetank and makes a bright spot on thepaper. With milk added, the light isscattered so that the spot is much less distinct. Visual

Use VisualsFigure 7 To emphasize that suspendedparticles settle out over time, ask, Whatwill happen to the particles of plasticsuspended in the air? (The particles will eventually settle out.) Discuss withstudents the dangers of inhalingsuspended particles. Ask, How does amask prevent the worker from inhal-ing particles of plastic? (The particles insuspensions can be separated by filtration.The mask is a filter.)Visual

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Properties of Matter 43

Answer to . . .

Figure 6 The solution and the colloidboth appear homogeneous.

Suspended particlessettle out of a mixture.

Section 2.1 Assessment

Reviewing Concepts1. Why does every sample of a given

substance have the same properties?

2. Explain why the composition of anelement is fixed.

3. Describe the composition of a compound.

4. Why can the properties of a mixture vary?

5. On what basis can mixtures be classifiedas solutions, suspensions, or colloids?

Critical Thinking6. Predicting If you added salt instead of sugar

to a pitcher of lemonade, how would thischange the properties of the lemonade?

7. Interpreting Visuals Explain why silicondioxide cannot be the only compound in thesample of sand shown in Figure 5.

8. Inferring Fresh milk is a suspension. Afterfresh milk is homogenized, it is a colloid. Whathappens to the size of the drops of fat in milkwhen milk is homogenized?

Writing Instructions Pick a cereal that isan obvious mixture. Write rules that could beused to control the cereal’s composition. Usethe FDA rules for mixed nuts as a model.

44 Chapter 2

Low beam

High beam

Colloids Milk is a mixture of substances including water, sugar, pro-teins, and fats. When fresh cow’s milk is allowed to stand, a layer ofcream rises to the top. This layer contains much of the fat in the milk.In the milk you buy at the store, the cream does not form a separate layer.The milk has been processed so that the fat remains dispersed through-out the milk. The result is homogenized milk, which is a colloid.

A colloid contains some particles that are intermediate in sizebetween the small particles in a solution and the larger particles in asuspension. Like solutions, colloids do not separate into layers. Youcannot use a filter to separate the parts of a colloid.

Fog is a colloid of water droplets in air. Figure 8 shows how fogaffects which headlights a driver uses. Automobiles have headlightswith low beams for normal driving conditions and high beams forroads that are poorly lit. With the high beams, a driver can see a bendin the road or an obstacle sooner. But the high beams are not useful ona foggy night because the water droplets scatter light back toward thedriver and reduce visibility. With the low beams, much less light is scat-tered. The scattering of light is a property that can be used todistinguish colloids and suspensions from solutions.

Figure 8 The photograph showshow water droplets in fog scatterthe light from high beams. Thedrawing compares the areas lit byhigh beams and low beams.Interpreting Diagrams Whichbeams normally make a largerarea of a road visible?

44 Chapter 2

Build Science SkillsClassifying Have interested studentsresearch categories of colloids such asgels, foams, aerosols, and emulsions.Have students find out how scientistsdistinguish different types of colloids.Have them identify household examplesof each type.Visual, Portfolio

ASSESSEvaluateUnderstandingHave students make a game of concen-tration using the terms in the chapterand their definitions. Have groups ofstudents write each term on separateindex cards and the definition of eachterm on a second set of index cards. Toplay the game, students should shuffleall the cards together and then lay themface down in a grid. Each student takesturns flipping over two index cards. Ifthe cards match, the student can removethe cards from the grid. If the cards donot match, the student places the cardsface down. After all of the cards aregone, the student who has removedthe most cards wins the match.

ReteachUse Figure 6 as a visual aid to summarizethe key differences among differenttypes of mixtures.

Students should specify whichingredients are required for the cereal toqualify for a particular label and suggesta range for ingredients such as driedfruit or nuts. (Students could chooseanother edible mixture, such as cannedvegetable soup.)

If your class subscribes tothe Interactive Textbook, use it toreview key concepts in Section 2.1.

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Section 2.1 (continued)

6. The lemonade would taste salty insteadof sweet.7. Silicon dioxide is colorless. There must be atleast one other compound in the sample toaccount for the dark-colored grains.8. Large drops are broken down into smallerdrops, which can remain dispersedthroughout the milk.

Section 2.1 Assessment

1. A pure substance has a fixed composition.2. An element contains only one kind of atom.3. Compounds contain two or more elementsjoined in a fixed proportion.4. Because the composition of a mixture isnot fixed5. Mixtures can be classified as solutions,suspensions, or colloids based on the sizeof their largest particles.Answer to . . .

Figure 8 High beams