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sections

1 Physical Properties andChanges

2 Chemical Properties andChangesLab Different ChangesLab Liquid Layers

Virtual Lab How are physicaland chemical changesdistinguished?

An Underwater Flame?Wendy Craig Duncan carried the Olympicflame underwater on the way to the 2000Summer Olympics in Sydney, Australia.How many different states of matter can youfind in this picture? In this chapter, you willlearn about the four states of matter, and thephysical and chemical properties of matter.

How many states of matter do yousee in this photo? List as many as you can.Science Journal

Sunshine State Standards—SC.A.1: The student understands that all matter has observable,measurable properties.

UnderstandingMatter

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Properties of Matter Makethe following Foldable to helpyou organize your thoughtsinto clear categories aboutproperties of matter.

Draw a mark at the midpoint of asheet of paper along the side edge.Then fold the top and bottom edgesin to touch the midpoint.

Fold in half from side to side.

Turn the paper vertically. Open and cut along the inside fold lines to form four tabs.

Label each tabas shown.

Classify Before you read the chapter, defineeach term on the front of the tabs. As you readthe chapter, correct your definitions and writeabout each under the appropriate tab. Use theinformation in your Foldable to compare andcontrast physical and chemical properties ofmatter. Write about each on the back of the tabs.

STEP 4

STEP 3

STEP 2

STEP 1

Can you classify pennies by theirproperties?Your teacher has given you a collection of pen-nies. It is your task to separate these penniesinto groups. In this chapter, you will learn howto identify things based on their physical andchemical properties. With an understanding ofthese principles of matter, you will discoverhow things are classified or put into groups.

1. Complete a safety worksheet.

2. Choose a property that will allow you toseparate the pennies into groups.

3. Classify and sort each penny based on thechosen property.

4. Explain how you classified the pennies.Compare your system of classificationwith those of others in the classroom.

5. Think Critically Write a paragraph inyour Science Journal explaining how yourgroup classified its pennies. What otherproperties could have been used to clas-sify the pennies?

Start-Up Activities

Preview this chapter’s contentand activities at fl6.msscience.com

PhysicalProperties

PhysicalChanges

ChemicalProperties

ChemicalChanges

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444 CHAPTER 15

Using Your SensesAs you look in your empty wallet and realize that your

allowance isn’t coming anytime soon, you decide to get an after-school job. You’ve been hired at the new grocery store that willopen next month. They are getting everything ready for thegrand opening, and you will be helping make decisions aboutwhere things will go and how they will be arranged.

When you come into a new situation or have to make anykind of decision, what do you usually do first? Most peoplewould make some observations. Observing involves seeing,hearing, tasting, touching, and smelling.

Whether in a new job or in the laboratory, you use your sensesto observe materials. It is important to never taste, touch, or smellany of the materials being used in the lab without guidance, asnoted in Figure 1. In the laboratory, you will rely mostly on otherobservations.

Physical Properties and Changes

■ Identify physical properties ofmatter.

■ Explain why materials withdifferent masses have differentdensities.

■ Observe water displacement todetermine volume.

■ Describe the states of matter.■ Determine how temperature

changes affect substances.■ Classify matter using physical

properties.

Observing physical properties will help you interpret the worldaround you.

Figure 1 In the laboratory, youusually use only two of yoursenses—sight and hearing. It isunsafe to touch, taste, or smell any chemicals.

Watch

Listen

Do NOTtouch

Do NOTsmell

Do NOTtaste

Benchmarks—SC.A.1.3.1 Annually Assessed (pp. 444–453): The student identifies various ways inwhich substances differ; SC.A.1.3.5 (p. 450): The student knows the difference between a physicalchange in a substance and a chemical change; SC.A.1.3.6 Annually Assessed (p. 448): The studentknows that equal volumes of different substances may have different masses.

Also covers: SC.A.1.3.4 (p. 449), SC.H.1.3.4 Annually Assessed (p. 443), SC.H.1.3.5 Annually Assessed (p. 448), SC.H.1.3.7 Annually Assessed (p. 443), SC.H.2.3.1 (pp. 445–447, 451–452)

Review Vocabularymass: amount of matter in an

object

New Vocabulary

• physical • melting pointproperty • boiling pointdensity physical

• states of changematter

FCAT Vocabulary

Matt Meadows

SECTION 1 Physical Properties and Changes 445

Physical PropertiesOn the first day of your new job, the boss gives you an inven-

tory list and a drawing of the store layout. She explains thatevery employee is going to help to create a system to organizethe merchandise. Where will you begin?

You decide to go to an existing grocery store to observe thephysical properties of the items on your list. A physical propertyis any characteristic of a material that can be observed or meas-ured without changing the identity of the material.

Color and Shape What patterns do you observe on yourinventory list? The list is organized by similarity of products, soyou go to an aisle to make observations.

In the laundry product aisle, color is the first physical prop-erty that you notice. The detergent packages come in a variety ofcolors. You also notice that each package has a different shape.Some packages are rectangular, some are square, and some aremore rounded. Shape and color are both physical properties ofmatter. You could arrange the detergent packages according tothese properties.

Texture The next area that you investigate is the produce sec-tion. You notice a wide variety of fruits and vegetables. As youpick up the different types of produce, you notice the way theyfeel. Some fruits have smooth skin, while others have prickly orfuzzy skin. Texture is a physical property that describes the waysomething feels when you touch it. Figure 2 shows the wide vari-ety of physical properties in produce. Each item has a uniquecombination of color, shape, and texture.

Figure 2 Color, shape, and texture are physical properties of matter.Describe the physical properties ofan apple.

Topic: Physical PropertiesVisit fl6.msscience.com for Weblinks to information about thephysical properties of water andisopropyl alcohol.

Activity Identify the physicalproperties of water and isopropylalcohol. Create a data table tocompare physical properties.

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446 CHAPTER 15 Understanding Matter

Transparent, Translucent, and Opaque The next area tobe observed is the dairy section. There are rows of milk contain-ers in various packaging. Some milk brands are packaged in card-board containers, while others are packaged in plastic containers.

In one glass container, you notice that chocolate milk is vis-ible through the glass. However, the same type of milk is not vis-ible through some plastic containers. Why can you see throughone container and not another? The glass container is transpar-ent—you can see through it. The plastic container is opaque—meaning that no light passes through it. Some plastic containersare neither opaque nor transparent. They allow some light topass through, but you can’t see through them like you can seethrough the glass container. The plastic in these containers istranslucent. Examples of a translucent, transparent, and opaquewindows are shown in Figure 3. Transparent, translucent, andopaque are physical properties.

Metallic Properties As you continue your walk through thestore, you observe canned food items. The cans are made ofmetal. What are the physical properties of metals? Metals are rel-atively hard. They can be hammered, pressed, or rolled into thinsheets. This is a physical property called malleability (ma lee uhBIH luh tee). Many metals can be drawn into wires, as shown inFigure 4. This property is called ductility (duk TIH luh tee).

At the grocery store, your employer might consider theproperties of metals when purchasing grocery carts and shelves.Metal grocery carts can be dented more easily than plastic carts,but might be less likely to break. The metal in shelves attractsmagnets which can be used to post prices and weekly specials.

Figure 3 These windows illus-trate the difference between trans-parent, translucent, and opaque.

Figure 4 This artist used theductility of metal to create thissculpture.

(tl)Paul A. Souders/CORBIS, (tc)Photodisc/Getty Images, (tr)Bibi Eng/Getty Images, (bl)Reuters/CORBIS


Length Some properties of matter can be identified by usingyour senses, such as color, shape, and texture. Other propertiescan be measured. How much is there? How much space does ittake up? One measurable physical property is length. Length ismeasured using a ruler, meterstick, or tape measure. Objects canbe classified by their length. For example, you could choose toorganize the bread in the bakery section of your store by thelength of the loaf.

Mass Back in the laundry aisle, you notice a child struggling tolift one of the boxes of detergent. That raises a question. Howmuch detergent is in each box? Mass is a physical property thatdescribes the amount of material in an object. The larger deter-gent boxes are heavier than the smaller boxes. In other words,the larger boxes have more mass than the smaller boxes.Organizing the boxes by mass is another option. You mightplace the boxes with more mass on the bottom shelves.

Volume Another physical property that describes how muchof something you have is volume. Volume measures the amountof space an object takes up. Liquids usually are measured byvolume. The juice bottles on your list could be organized by volume.

What term describes the amount of material inan object?

Measuring Volume Thereare two methods used formeasuring the volume of asolid, such as a cube. The firstmethod is by measuring thelength (�), width (w), andheight (h) of the cube. Thevolume is then determined by multiplying length, width,and height (V � � � w � h).Another method for deter-mining the volume of a solidis by immersion. The object isplaced in a known volume ofwater. The difference in thevolume of water before andafter the object is addedequals the object’s volume.

Figure 5 Water displacement isused to determine the volume ofirregularly shaped objects.Explain how you would determinethe volume of a brick.

Annually AssessedBenchmark Check

SC.A.1.3.1 Choose two objectsand describe their physical properties.

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Initialvolume:60.5 mL

Final volume:64.5 mL

The rock has a volume of 4.0 mL

Matt Meadows

Density Another measurable physical property related to massand volume is density—the amount of mass a material has in agiven volume. If two objects have the same volume, the moremassive object is more dense. Density is a physical property of asubstance that does not change. Therefore, you can determinethe identity of an unknown substance by calculating its density.Density is calculated by dividing the mass of a substance by itsvolume.

Same Volume, Different Mass Figure 6 shows two ballsthat are the same size but not the same mass. The bowling ballis more dense than the kickball. The customers of your grocerystore will notice the density of their bags of groceries if the bag-gers load all of the canned goods in one bag and put all of thecereal and napkins in the other.

What two properties are related in the measurement of density?

Liquid Layers Some salad dressings are made with oil andwater. Before you use these types of dressings, you are advised toshake the bottle vigorously. Why is this? If you look closely at thebottle before shaking it, you will notice two liquid layers. Onelayer is oil and the other is water. Oil and water form two sepa-rate layers because their densities are different. The density of oilis less than the density of water. Therefore, the oil is the top layer.When two or more substances are mixed, they will form layersin order of density. The substance with the greatest density willform the bottom layer. The one with the lowest density will formthe top layer.

Density � �vo

mluamss

e� or D � �

mV

�

Figure 6 These balls take upabout the same space, but thebowling ball has more mass thanthe kickball. The bowling ball ismore dense.


Bowling ball Kickball

Determining DensityProcedure1. Complete a safety

worksheet.2. Find three objects of the

same size. For example: amarble, a rubber ball, anda wood sphere.

3. Measure the mass of eachobject using a balance.Record the mass in yourScience Journal.

4. Fill a 100-mL graduatedcylinder with 50 mL ofwater.

5. Submerge one object intothe graduated cylinder andrecord the new water level.Empty the cylinder.

6. Repeat steps 3 and 4 forthe remaining two objects.

Analysis1. Create a data table.2. Determine the volume and

density for each object.

SC.A.1.3.6SC.H.1.3.5

Annually AssessedBenchmark Check

SC.A.1.3.6 A tennis ball has avolume of 230 cm3 and a densityof 0.25 g/cm3. A baseball has avolume of 230 cm3 and a densityof 0.65 g/cm3. What is the mass of each ball?

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Aaron Haupt

An animated version of this diagram is available atfl6.msscience.com

Solid water Liquid water Gaseous water


Figure 7 The molecules in iceare tightly packed and vibrate inplace. In liquid water they can slippast each other because they havemore energy to move. In watervapor, they fill the entire containerand move with even more energy.

States of MatterWhat happens to ice cream if you leave it out on the kitchen

counter? It melts into a soupy mess. Its state of matter changesfrom a solid to a liquid. The four states of matter are solid, liq-uid, gas, and plasma (PLAZ muh). When you organize the prod-ucts in your grocery store, you probably should understandsomething about each product’s state of matter. You might befamiliar with three of these—solids, liquids, and gases. However,you might not be familiar with plasma. While very common inthe universe, plasma is less common on Earth. Plasma exists inlightening, fluorescent bulbs, and neon signs. Besides theirappearance, how do the states of matter differ?

Moving Particles Matter is made up of moving particles. Thestate of matter is determined by how much energy the particleshave. Molecular motion increases as matter changes from a solidto a liquid and to a gas. The particles of a solid vibrate in a fixedposition. They remain close together and give the solid a definiteshape and volume. The particles of a liquid are moving muchfaster and have enough energy to slide past one another. Thisallows a liquid to take the shape of its container. The particles ofa gas are moving so quickly that they have enough energy tomove freely away from other particles. The particles of a gas takeup as much space as possible and will spread out to fill any con-tainer. Figure 7 illustrates the differences in the states of water.



Melting and Boiling Points Thetemperature at which a solid becomes aliquid at a given pressure is its meltingpoint. The temperature at which a liq-uid becomes a gas at a given pressure isits boiling point. Melting and boilingpoints are physical properties that canbe used to identify an unknown sub-stance. At atmospheric pressure, wateralways melts at 0°C and boils at 100°C.Nitrogen boils at �195.8°C at atmos-pheric pressure. The change of liquidnitrogen to gaseous nitrogen is shownin Figure 8.

What physicalchange takes placeat the boiling point?

Physical ChangesYou have learned about several physical properties that you

can observe with your senses and that you can measure. Now youwill learn about changes in these properties. In a physical change,the physical properties of a substance change but the identity ofthe substance does not change. For example, if you cut an applein half, many of its physical properties change. Each half has adifferent shape, a different mass, and takes up a different volumethan the whole. However, the halves are still made of the samesubstances. One type of physical change is a change of state.

Changes of State You have already read about melting andboiling. Melting and boiling are physical changes. Freezing, orthe change of a liquid to a solid, also is a physical change.Condensation is the change of a gas to a liquid. For example,water vapor in the air condenses into clouds and into dropletson cold surfaces such as a bathroom mirror. Boiling, condens-ing, freezing, and melting all are physical changes.

Another physical change is sublimation. Sublimation is thechange of a solid to a gas without becoming a liquid. One exam-ple of sublimation is the change of solid carbon dioxide—dryice—to gaseous carbon dioxide. Dry ice is used to keep thingscold.

For your job at the grocery store, you will need to considerchanges of state when organizing products. Some items must bekept frozen while others must be kept at room temperature.

Figure 8 When liquid nitrogenis poured from a flask, you see aninstant change to gas becausenitrogen’s boiling point is–195.8°C, which is much lowerthan room temperature.

Liquid nitrogen (below –195.8°C)

Nitrogen gas (above –195.8°C)

David Taylor/SPL/Photo Researchers

Using PhysicalProperties

In thepreviouspages,manyphysical properties were dis-cussed. These physical proper-ties—suchasappearance,state,shape, length, mass, volume,texture, density, melting point,boiling point, malleability, andductility—can be used to helpyou identify, separate, and clas-sify substances.

For example, salt can bedescribed as a white solid.Each salt crystal, if you look atit under a microscope, couldbe described as having a three-dimensional cubic structure.You can measure the density,melting point, and boilingpoint of a sample of salt. These physical properties can be usedto identify an unknown substance.

Sorting and Separating When you do laundry, you sortaccording to physical properties. Perhaps you sort by color.When you select a heat setting on an iron, you classify theclothes by the type of fabric. When miners during the GoldRush panned for gold, they separated the dirt and rocks by thedensity of the particles. Figure 9 shows a coin sorter that sepa-rates the coins based on their size. Iron filings can be separatedfrom sand by using a magnet.

Scientists who work with animals usephysical properties or characteristics

to determine the identity of a specimen. They do this by usinga system called a dichotomous (di KAH tuh mus) key. The term dichotomous refers to two parts or divisions. Part ofa dichotomous key for identifying hard-shelled crabs is shown on the next page in Figure 10. To begin the identifica-tion of your unknown animal, you are given two choices.Your animal will match only one of the choices. In the key inFigure 10, you are to determine whether or not your crab livesin a borrowed shell. Based on your answer, you are eitherdirected to another set of choices or given the name of thecrab you are identifying.


Figure 9 Coins can be sorted bytheir physical properties. Sortingby size is used here.Identify three other properties thatcan be used to sort coins.

Field Biologists Scientistswho investigate plants andanimals in their environ-ment are field biologists.These scientists work andsometime live in the envi-ronment that they arestudying. Field biologistsare employed by govern-ment agencies, industries,and private business. Inyour Science Journal,research and describe whatcareers are available tofield biologists.

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Figure 10

VISUALIZING DICHOTOMOUS KEYS

452 CHAPTER 15

Whether in the laboratory or in the field, scientists oftenencounter substances

or organisms that they cannot imme-diately identify. One approach totracking down the identity of such“unknowns” is to use a dichotomouskey, such as the one shown. The key is designed so a user can comparephysical properties or characteristicsof the unknown substance or organ-ism—in this case, a crab—with characteristics of known organisms ina stepwise manner. With each step, achoice must be made. Each choiceleads to subsequent steps that guidethe user through the key until a posi-tive identification is made.

A. Lives in a “borrowed” shell(usually some type of snail shell)

B. Does not live in a “borrowed” shell

A. Shell completely overlaps the walking legs

B. Walking legs are exposed

Hermit Crab

go to #2

Box Crab

Kelp Crab

1.

2.

Dichotomous Key

Can you identify thethree crabs shownhere by following thisdichotomous key?

(l)Steve Kaufman/CORBIS, (tr)Tom McHugh/Photo Researchers, (br)Fred Bavendam/Minden Pictures


Self Check1. Identify the physical properties of this textbook.

2. List the three states of water in order from fastest toslowest particle movement.

3. Explain how water might have two different densities.

4. Think Critically Which evaporates more quickly—rubbing alcohol that has been refrigerated orunrefrigerated?

SummaryPhysical Properties

• Physical properties include color, shape,length, mass, volume, and density.

States of Matter

• There are four states of matter.

• Matter can change from one state of matterto another.

• State of matter is determined by how muchenergy the particles have.

Using Physical Properties

• Substances can be classified according to theirphysical properties.

5. Solve One-Step Equations Nickel has a density of9.8 g/cm3. Lead has a density of 11.3 g/cm3. If both sam-ples have a volume of 4 cm3, what are the massesof each?

Everyday Examples Identification by physical properties is asubject in science that is easy to observe in the real world. Supposeyou volunteer to help your friend choose a family pet. While vis-iting the local animal shelter, you spot a cute dog. The dog lookslike the one in Figure 11. You look at the sign on the cage. It saysthat the dog is male, one to two years old, and its breed isunknown. You and your friend wonder what breed of dog he is.What kind of information do you and your friend need to figureout the dog’s breed? First, you need a thorough description of thephysical properties of the dog. What does the dog look like?Second, you need to know the descriptions of various breeds ofdogs. Then you can match up the description of the dog with thecorrect breed. The dog you found is a white, medium-sized dogwith large black spots on his back. He also has black ears and ablack mask around his eyes. The manager of the shelter tells youthat the dog is close to full-grown. What breed is the dog?

Narrowing the Options To find out, you may need to researchthe various breeds of dogs and their descriptions. Often, determin-ing the identity of something that is unknown is easiest by usingthe process of elimination. You figure out all of the breeds the dogcan’t be. Then your list of possible breeds is smaller. Upon lookingat the descriptions of various breeds, you eliminate small dog andlarge dog breeds. You also eliminate breeds that do not containwhite dogs. With the remaining breeds, you might look at photosto see which ones most resemble your dog. Scientists use similarmethods to determine the identities of living and nonliving things.

Figure 11 Physical descriptionsare used to determine the identi-ties of unknown things. Observe What physical propertiescan be used to describe this dog?

More Section Review fl6.msscience.com

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Ability to ChangeIt is time to celebrate. You and your coworkers have cooper-

ated in classifying all of the products and setting up the shelvesin the new grocery store. The store manager agrees to a celebra-tion party and campfire at the nearby park. Several large piecesof firewood and some small pieces of kindling are needed tostart the campfire. After the campfire, all that remains of thewood is a small pile of ash. Where did the wood go? What prop-erty of the wood is responsible for this change?

All of the properties that you observed and used for classifi-cation in the first section were physical properties that you couldobserve easily. In addition, even when those properties changed,the identity of the object remained the same. Something differ-ent seems to have happened in the bonfire example.

Some properties do indicate a change of identity for the sub-stances involved. A chemical property is any characteristic thatgives a substance the ability to undergo a change that results ina new substance. Figure 12 shows some properties of substancesthat can be observed only as they undergo a chemical change.

What does a chemical property give a substancethe ability to do?

Chemical Properties and Changes

■ Recognize chemical properties.■ Identify chemical changes.■ Classify matter according to

chemical properties■ Describe the law of conservation

of mass.

Knowing the chemical propertieswill allow you to distinguish differ-ences in matter.

Figure 12 These are four examples of chemical properties.

Flammability Reacts with oxygen Reacts with light Reacts with water

Benchmarks—SC.A.1.3.1 Annually Assessed (pp. 454–458): The student identifies various ways inwhich substances differ; SC.A.1.3.5 (pp. 454–460): The student knows the difference between a physi-cal change in a substance and a chemical change.

Also covers: SC.A.1.3.6 Annually Assessed (pp. 462–463), SC.H.1.3.1 Annually Assessed (p. 464),SC.H.1.3.5 Annually Assessed (p. 458), SC.H.1.3.6 (pp. 455, 464), SC.H.3.3.4 (p. 458), SC.H.3.3.5 (pp. 459, 464)

Review Vocabularyheat: a form of energy that

flows from a warmer object to acooler object

New Vocabulary

• chemical propertychemical change

• law of conservation of mass

FCAT Vocabulary

(l)Richard Megna/Fundamental Photographs, (cl)John Lund/Stone/Getty Images, (r)T.J. Florian/Rainbow/PictureQuest, (cr)Richard Pasley/Stock Boston

SECTION 2 Chemical Properties and Changes 455

Common Chemical PropertiesYou don’t have to be in a laboratory to see the changes that

take place because of chemical properties. These are called chem-ical changes. A chemical change is a change in the identity of asubstance due to the chemical properties of that substance. A newsubstance or substances are formed as a result of such a change.

The campfire you enjoyed to celebrate the opening of thegrocery store resulted in chemical changes. The oxygen in the airreacted with the wood to form a new substance called ash. Woodcan burn. This chemical property is called flammability. Someproducts have warnings on their labels about keeping themaway from heat and flame because of the flammability of thematerials. Sometimes after a campfire you see stones that didn’tburn around the edge of the ashes. These stones have the chem-ical property of being incombustible.

Common Reactions An unpainted iron gate, such as the oneshown in Figure 13, will rust in time. The rust is a result of oxy-gen in the air reacting with the iron and causing corrosion. Thecorrosion produces a new substance called iron oxide, alsoknown as rust. Other chemical reactions occur when metalsinteract with other elements. The middle photo shows tarnish,the grayish-brown film that develops on silver when it reactswith sulfur in the air. The ability to react with oxygen or sulfuris a chemical property. The photo on the right shows anotherexample of this chemical property.

Have you ever sliced an apple or banana and left it sitting onthe table? The brownish coloring that you notice is a chemicalchange that occurs between the fruit and the oxygen in the air.Those who work in the produce department at the grocery storemust be careful with any fruit they slice to use as samples.Although nothing is wrong with brown apples, they don’tlook appetizing.

An untreated iron gate will rust.

Figure 13 Many kinds of inter-actions with oxygen can occur.Copper sculptures develop a greenpatina, which is a mixture of cop-per compounds.

Enzyme ResearchResearchers have discov-ered an enzyme in fruitthat is involved in thebrowning process. They aredoing experiments to try togrow grapevines in whichthe level of this enzyme,polyphenol oxidase (PPO),is reduced. This couldresult in grapes that do notbrown as quickly. Write aparagraph in your ScienceJournal about why thiswould be helpful to fruitgrowers, store owners, andcustomers.

Silver dishes develop tarnish.

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(l)Philippe Colombi/Getty Images, (c)Michael Newman/PhotoEdit, Inc., (r)Roger K. Burnard


Heat and Light Vitamins often are dispensed in dark-brownbottles. Do you know why? Many vitamins will change whenexposed to light. This is a chemical property. They are protectedin those colored bottles from undergoing a chemical changewith light.

Some substances are sensitive to heat and will undergo a chemical change when heated or cooled. One example is limestone. Limestone is generally unreactive. Some limestoneformations have been around for centuries without changing.However, if limestone is heated, it undergoes a chemical changeand produces carbon dioxide and lime, a chemical used in manyindustrial processes. The chemical property in this case is theability to change when heated.

Another chemical property is the ability to change with elec-trical contact. Electricity can cause a change in some substancesand decompose some compounds. Water is one of those com-pounds that can be separated into its components of hydrogenand oxygen using electricity.

Something NewThe important difference in a chemical change is that a

new substance is formed. Because of chemical changes, you can enjoy many things in life that you would not have experi-enced without them. What about that perfect, browned marsh-mallow you roasted at the campfire? A chemical changeoccurred as a result of the fire to make the taste and the

appearance different.Sugar is normally a white,

crystalline substance, but afteryou heat it over a flame, it turnsto a dark-brown caramel. Anew substance has beenformed. Sugar also can under-go a chemical change when sul-furic acid is added to it. Thenew substance has obviouslydifferent properties from theoriginal, as shown in Figure 14.

If eggs, sugar, flour, andother ingredients didn’t changechemically through baking, youcouldn’t enjoy birthday cake.Cake begins as liquid and endsas solid. The baked cake clearlyhas different properties.

Figure 14 When sugar and sulfuric acid combine, a chemicalchange occurs and a new sub-stance forms. During this reaction,the mixture foams and a toxic gasis released, leaving only water andair-filled carbon behind.

Matt Meadows


Signs of Change How do you know that you have anew substance? Is it just because it looks different? Youcould put a salad in a blender and it would look differ-ent, but a chemical change would not have occurred.You still would have lettuce, carrots, and any other veg-etables that were there to begin with.

You can look for signs when evaluating whether youhave a new substance as a result of a chemical change.Look at the piece of birthday cake in Figure 15. When acake bakes, gas bubbles form and grow within the ingre-dients. Bubbles are a sign that a chemical change hastaken place. When you look closely at a piece of cake,you can see the airholes left from the bubbles.

Other signs of change include the production of heat, light,smoke, change in color, and sound. Which of these signs of changewould you have seen or heard during the campfire?

Is it reversible? One other way to determine whether aphysical change or a chemical change has occurred is to decidewhether or not you can reverse the change by simple physicalmeans. Physical changes usually can be reversed easily. Forexample, melted butter can become solid again if it is placed inthe refrigerator. A figure made of modeling clay, like the one inFigure 16, can be smashed to fit back into a container. However,chemical changes can’t be reversed using physical means. Forexample, the ashes in a fireplace cannot be put back together tomake the logs that you had to start with. Can you find the egg ina cake? Where is the white flour?

What kind of change can be reversed easily?

Figure 16 A change such asmolding clay can be undone easily.

Figure 15 The evidence of achemical change in the cake is theholes left by the air bubbles thatwere produced during baking.Identify other examples of achemical change.

(t)Ralph Cowan, (others)Aaron Haupt


Classifying According to Chemical PropertiesClassifying according to physical properties is often easier thanclassifying according to chemical properties. Table 1 summa-rizes the two kinds of properties. The physical properties of asubstance are easily observed, but the chemical properties can’tbe observed without changing the substance. However, once youknow the chemical properties, you can classify and identify mat-ter based on those properties. For example, if you try to burnwhat looks like a piece of wood but find that it won’t burn, youcan rule out the possibility that it is wood.

In a grocery store, the products sometimes are separatedaccording to their flammability or sensitivity to light or heat.You don’t often see the produce section in front of big windowswhere heat and light come in. The fruit and vegetables wouldundergo a chemical change and ripen too quickly. You alsowon’t find the lighter fluid and rubbing alcohol near the bakeryor other places where heat and flame could be present.

Architects and product designers have to take into accountthe chemical properties of materials when they design buildingsand merchandise. For example, children’s sleepwear and bed-ding can’t be made of a flammable fabric. Also, some of thearchitects designing the most modern buildings are choosingmaterials like titanium because it does not react with oxygen likemany other metals do.

The Law of Conservation of MassIt was so convenient to turn the firewood into the small pile

of ash left after the campfire. You began with many kilograms offlammable substances but ended up with just a few kilograms ofash. Could this be a solution to the problems with landfills andgarbage dumps? Why not burn all the trash? If you could makesuch a reduction without creating undesirable materials, thiswould be a great solution.

Table 1 Comparing Properties

Physical Properties color, shape, length, mass, volume, density, state, ability to attract a magnet, melting point, boiling point, malleability, ductility

Chemical Properties flammability; ability to react with oxygen, water, vinegar; ability to react in the presence of electricity, light, heat, etc.

Observing YeastProcedure

1. Observe a tablespoon ofdry yeast with amagnifying lens. Drawand describe what youobserve.

2. Put the yeast in 50 mL ofwarm, not hot, water.

3. Compare your observationsof the dry yeast with thoseof the wet yeast.

4. Put a pinch of sugar in the water and observe for 15 minutes.

5. Record your observations.

Analysis1. Are new substances formed

when sugar is added to thewater and yeast? Explain.

2. Do you think this is achemical change or aphysical change? Explain.

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Mass Is Not Destroyed Before you celebrate your discov-ery, think this through. Did mass really disappear during thefire? It appears that way when you compare the mass of the pileof ashes to the mass of the firewood you started with. The law ofconservation of mass states that the mass of what you end withis always the same as the mass of what you start with.

This law was first investigated about 200 years ago, and manyinvestigations since then have proven it to be true. One experi-ment done by French scientist Antoine Lavoisier was a small ver-sion of a campfire. He determined that a fire does not makemass disappear or truly get rid of anything. The question, how-ever, remains. Where did the mass go? The ashes aren’t heavyenough to account for the mass of all of the pieces of firewood.

Where did the mass go? If you look at the campfire exam-ple more closely, you see that the law of conservation of mass istrue. When flammable materials burn, they combine with oxygen.Ash, smoke, and gases are produced. The smoke and gases escapeinto the air. If you could measure the mass of the oxygen and allof the original firewood that was burned and compare it to theremaining mass of the ash, smoke, and gas, they would be equal.

Do light sticks conserve mass?

Light sticks often are used onHalloween to light the way for trick-

or-treaters. They make children visibleto drivers. They also are used as toys,for camping, marking trails, emergencytraffic problems, and by the military.They work well underwater. A lightstick contains two chemicals in sepa-rate tubes. When you break the innertube, the two chemicals react produc-ing a greenish light. The chemicals arenot toxic, and they will not catch fire.

Identifying the Problem In all reactions that occur in the

world, mass is never lost or gained.This is the law of conservation of mass.An example of this phenomenon is thelight stick. How can you prove this?

Solving the Problem Describe how you could show that a

light stick does not gain or lose masswhen you allow the reaction to takeplace. Is this reaction a chemical orphysical change? What is your evidence?


Topic: Antoine LavoisierVisit fl6.msscience.com for Weblinks to information about AntoineLavoisier, the founder of modernchemistry.

Activity Research the nonscien-tific portion of Lavoisier’s life.Write a 2-paragraph magazinearticle from your findings.

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Self Check1. Define What is a chemical property? Give four

examples.

2. Identify some of the signs that a chemical change hasoccurred.

3. Think Critically You see a bright flash and then flamesduring a class demonstration. Is this an example of aphysical change or a chemical change? Explain.

4. Solving One-Step Equations A student heats 4.00 g ofa blue compound, which reacts completely to produce2.56 g of a white compound and an unknown amountof colorless gas. What is the mass of this gas?

Figure 17 This reaction demon-strates the law of conservation ofmass. Although a chemical changehas occurred and new substanceswere made, the mass remainedconstant.

SummaryCommon Chemical Properties

• A new substance, or substances, form(s) as a result of a chemical change.

• Exposure to oxygen, heat, and light cancause chemical reactions.

Something New

• Physical changes can be reversed. Chemicalchanges cannot be reversed.

• Substances can be classified according totheir chemical properties.

The Law of Conservation of Mass

• Mass is not gained or lost during a chemi-cal reaction.

Before and After Mass is not destroyed or created duringany chemical change. The law of conservation of mass isdemonstrated in Figure 17. In the first photo, you see one sub-stance in the flask and a different substance contained in a testtube inside the flask. The total mass is 16.150 g. In the secondphoto, the flask is turned upside down. This allows the two sub-stances to mix and react. Because the flask is sealed, nothing isallowed to escape. In the third photo, the flask is placed on thebalance again and the total mass is determined to be 16.150 g. Ifno mass is lost or gained, what happens in a reaction? Instead ofdisappearing or appearing, the particles in the substancesrearrange into different combinations with different properties.

More Section Review fl6.msscience.com

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Timothy Fuller


The products of both chemical and physicalchanges appear different from the startingmaterials. How can you tell these two types ofchanges apart? If a change is not reversibleusing physical processes, it is a chemicalchange. If a change can be reversed by physicalprocesses, it is a physical change. In this lab youwill investigate chemical and physical changes.

Real-World ProblemHow can we distinguish physical and chemicalchanges?

Goals■ Observe the properties of substances.■ Examine changes in properties of

substances.■ Determine which changes are physical and

which are chemical.

Materials250-mL beaker (3) boraxwater balancetable sugar graduated cylindershallow pan (2) stirring rodwhite glue

Safety PrecautionsComplete a safety worksheet before you begin.

Procedure1. Describe the physical properties of sugar,

borax, water, and glue in your Science Journal.

2. In a beaker, dissolve 15 g of sugar to 100 mLof water. Record your observations. Set thebeaker aside.

3. In another beaker, dissolve 4 mL of borax in100 mL of water to make a borax solution.

4. In a third beaker, stir 50 mL of glue into 50 mL of water to make a glue solution.

5. Slowly add 50 mL of borax solution to theglue solution and stir the mixture.

6. Record the properties of the mixture.

7. Place both the sugar solution and the mix-ture into separate shallow pans and leavethem out overnight.

8. Record the properties of the substances thenext day.

Conclude and Apply1. Compare and contrast the properties of

the substances before and after they weremixed.

2. Describe the differences between the twosolutions after left overnight.

3. Infer which changes were physical andwhich were chemical. Explain the reasonsfor your conclusions.

Different Changes

Try making the glue-borax polymer withdifferent amounts of borax solution or theglue-water mix. Describe any differences inthe properties of the polymers. For morehelp, refer to the Science Skill Handbook.

LAB 461

Benchmark—SC.A.1.3.5: The student knows the difference between a physical changein a substance (i.e., altering the shape, form, volume, or density) and a chemical change(i.e., producing new substances with different characteristics); SC.A.1.3.1: identifies vari-ous ways in which substances differ; SC.H.1.3.5: knows that a change in one or morevariables may alter the outcome of an investigation.

Design Your OwnDesign Your Own


Real-World ProblemOil and other liquids often have to betransported across vast oceans. What ifthe tanker carrying these liquids leaks orsinks? Liquids that escape the tankermust be removed from the ocean quicklyto minimize the danger to humans andocean-dwelling organisms. Will cleanupcrews be removing the liquids from thebottom of the ocean or from its surface?

Form a HypothesisUsing what you’ve learned about density, predict whether equal vol-umes of three different liquids will have the equal or different masses.Predict what will happen when these liquids are mixed. Also, predictwhether the same mass of three different liquids will have equal ordifferent volumes. Predict what will happen when these liquids aremixed. Form a hypothesis to explain your predictions.

Test Your HypothesisMake a Plan1. As a group, discuss your four predictions. Agree on a hypothesis

that will explain your predictions.

2. Identify the results that will confirm your predictions and yourhypothesis.

3. Choose and organize the steps you will take to confirm each ofthe four predictions your group made. For each group of liquidstested, select the variable that your group will change. Determineconstants. Determine which variables will be measured. What cal-culations will need to be made to confirm your hypothesis?

4. Construct data tables for each group of liquids tested. Determinecolumn headings, row headings, and units of measurements.

5. Think through each step of your plan to make sure you haven’t for-gotten anything.

Goals■ Design an experiment

to observe whether liquids float or sink inother liquids.

■ Predict whether a liquid will float or sink on another liquid.

Possible Materials100 mL beaker (2)graduated cylinder (3)20–30 mL each of liquids

A, B, and C prepared byyour teacher

Safety Precautions

Complete a safety work-sheet before you begin.

Liquid Layers

Benchmark—SC.A.1.3.1: The student identifies various ways in which substances differ(e.g., mass, volume, shape, density, texture, and reaction to temperature and light);SC.A.1.3.6: The student knows that equal volumes of different substances may have dif-ferent masses.

Reuters/CORBIS

Follow Your Plan1. Make sure your teacher approves your plan before you start.

2. Carry out the experiment according to your approved plan. When making measurements, write possible sources of error in your Science Journal.

3. Record all observations and complete your data table in your Science Journal.

Analyze Your Data1. Complete any calculations necessary to confirm your hypothesis.

2. Write a statement that summarizes the result of each test.

3. Identify at least 3 sources of error in your experiment. Explain how each sourceof error could have affected your results.

Conclude and Apply1. Did your results support your hypothesis? If so, explain how your hypothesis

was supported. If not, determine whether you would change your experimen-tal plan or modify your hypothesis and explain your choice.

2. Explain why the substances formed the layers in the order that they did.

3. Predict what would happen if you combined three different substances ofequal mass together with the same three substances of equal volume.

4. Predict Would you expect the density of 15 mL of water to be the same as thedensity of 10 g of water? Explain.

5. Predict Would you expect the density of 15 g of water tosink or float on 10 g of corn oil? What data would you needto make a prediction?

6. Apply Would you expect crude oil in an oil tanker to float orsink in the salty ocean water? What data would you need toanswer this question?

As a group, create a diagram of each groupof liquids you combined. Label each layerwith its density. Compare your diagramswith those of other groups. Discuss anydifferences.

LAB 463Photo Researchers

Investigate Research the two types of particle accelerators.Compare how they work and their sizes. Describe what scientistslearn about atomic structure using these machines. Use the link tothe right or your school’s media center to get started.

SCIENCEAND

HISTORYSCIENCE

CAN CHANGE THE COURSE OF HISTORY!

What a Ride!Front wheel drive, a powerful motor, and

a smooth ride are characteristics to look forin an automobile. This car, developed byNippondenso, packs it all under a gold platedhood. At 4.78 mm long, this car is about the sizeof a grain of rice! Created to show the power andpotential of technology applied to unimaginablysmall objects, this car demonstrates a fraction ofthe knowledge scientists have gained in explor-ing matter on a very small scale.

Matter MilepostsPhilosophers and scientists have speculated

about the building blocks of matter for centuries.Around 425 B.C., the Greek Democritis used theterm “atomos” to describe the indivisible parti-cles making up matter of all types.

While early thinkers typically lacked the abil-ity to test their theories, later technologicaladvances applied to the study of matter movedscience from the realm of the philosophical tothe quantitative. In the 1700s, scientists experi-mented with gases, a type of matter difficult toconfine and hard to study. Their findings elimi-nated the last of the old Greek notions and laidthe foundation for modern chemistry.

It was the work of French scientist AntoineLavoisier (1743–1794) which earned him the title“Father of Modern Chemistry.” By focusing onmeasurable, quantifiable data, he forever changedthe way science was conducted. Lavoisier’s exper-

iments with gases led to the development of thelaw of conservation of mass, a cornerstone ofmodern chemistry which helps explain what hap-pens to matter during chemical change.

A Changing Road MapIn the 1930s, scientists used the first particle

accelerators to reveal the composition of theatom. These machines accelerate subatomic par-ticles, like electrons, to speeds close to the speedof light. Collisions at this speed cause these par-ticles to shatter, and provide the opportunity todetect and analyze the smaller particles whichcomprise them.

Once thought to be the smallest buildingblocks, the proton, neutron, and electron are nowjoined by other subatomic particles groups,including quarks. Scientists currently believe thequark is the most fundamental particle. Studyingparticles created in particle accelerators is difficultbecause most exist for less than a billionth of asecond.

As the technology behind these powerfulmachines advances, current hypotheses willundergo revision. Thenature of scientific study isto build upon and extend,while sometimes uprooting,commonly held theories.Experimentation to discoverthe building blocks of mat-ter is no exception.

The Road to Understanding Matter

For more information, visitfl6.msscience.comLA.A.2.3.5 LA.B.2.3.1

(t)Denso/Rex Features, (b)Alexander Tsiaras/Photo Researchers


Copy and complete the following table comparing properties of different objects.

Physical Properties and Changes

1. Any characteristic of a material that can beobserved or measured is a physicalproperty.

2. The four states of matter are solid, liquid,gas, and plasma. The state of matter isdetermined by the energy the particles have.

3. Color, shape, length, mass, volume, density,texture, melting point, boiling point, arecommon physical properties.

4. In a physical change the properties of asubstance change but the identity of thesubstance always stays the same.

5. You can classify materials according to theirphysical properties.

Chemical Properties and Changes

1. Chemical properties give a substance theability to undergo a chemical change.

2. Common chemical properties include:ability to burn, reacts with oxygen, reacts inthe presence of heat or light, and breaksdown with electricity.

3. In a chemical change substances combineto form a new material.

4. The mass of the products of a chemicalchange is always the same as the mass ofwhat you started with.

5. A chemical change results in a substancewith a new identity, but matter is not created or destroyed.

CHAPTER STUDY GUIDE 465

Properties of Matter

Type of Matter Physical Properties Chemical Properties

Log

Pillow

Bowl of cookie dough

Book

Glass of orange juice

Interactive Tutor fl6.msscience.com(l)John Evans, (r)Siede Preis/Getty Images

Do not write in this book.


Fill in the blanks with the correct vocabularyword or words.

1. The __________ is the temperature at whichmatter in a solid state changes to a liquid.

2. __________ is a measure of the mass of anobject in a given volume.

3. A(n) __________ is easily observed or meas-ured without changing the object.

4. __________ result in a new substance andcannot be reversed by physical means.

5. Solid, liquid, and gas are all examples of__________.

Choose the word or phrase that best answers thequestion.

6. Which is an example of a physical change?A) burning C) rustingB) melting D) tarnishing

7. Which is a sign that a chemical change hasoccurred?A) smoke C) change in shapeB) broken pieces D) change in state

8. Particles in which state of matter vibrate ina fixed position?A) gas C) steamB) ice D) water

9. What is density?A) the amount of mass for a given volumeB) the amount of space an object takes upC) the distance between two points D) how light is reflected from an object’s

surface

Use the table below to answer question 10.

10. Which liquid below has the greatest density? A) corn syrupB) milkC) orange juiceD) vinegar

11. Which is a chemical property?A) densityB) flammabilityC) sizeD) volume

12. What change results in a new substancebeing produced?A) chemicalB) change of stateC) massD) physical

13. What is conserved during any change?A) color C) massB) identity D) volume

466 CHAPTER REVIEW

boiling point p. 450chemical change p. 455chemical property p. 454density p. 448law of conservation

of mass p. 459

melting point p. 450physical change p. 450physical property p. 445states of matter p. 449

Physical Properties of Liquids

Liquid Mass (g) Volume (cm3)

Corn syrup 15.3 14.2

Milk 12.5 12.1

Orange juice 27.5 25.0

Vinegar 8.3 8.2

Vocabulary PuzzleMaker fl6.msscience.com

FCAT Vocabulary

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CHAPTER REVIEW 467

14. Explain Use the law of conservation of massto explain what happens to atoms whenthey combine to form a new substance.

15. Describe the four states of matter. How arethey different?

16. Observe A globe is placed on your desk andyou are asked to identify its physical prop-erties. How would you describe the globe?

17. Evaluate What information do you need toknow about a material to find its density?

18. Classify the following as a chemical or phys-ical change: an egg breaks, a newspaperburns in the fireplace, a dish of ice creamis left out and melts, and a loaf of bread isbaked.

19. Draw Conclusions The densities of three liq-uids are 0.85 g/mL, 1.13 g/mL, and 0.96g/mL. Which liquid would be on the top,middle, and bottom if they were com-bined. Explain.

20. Infer Concrete is formed through a chemicalreaction of sand, gravel, crushed stones, andwater. Do the starting materials have thesame properties as the end materials? Givetwo examples to support your response.

21. Describe In terms of particle movementexplain how increasing temperaturechanges water in the solid state.

22. Concept Map Use a spider map to organizeand define physical properties of matter.Include the concepts of color, shape,length, density, mass, states of matter, vol-ume, density, melting point, and boilingpoint.

23. Comic Strip Create a comic strip demon-strating a chemical change in a substance.Include captions and drawings thatdemonstrate your understanding of thelaw of conservation of mass.

24. Measure in SI Find the density of the piece oflead that has a mass of 49.01 g and a volume of4.5 cm3.

Use the table below to answer question 25.

25. Density Copy and complete the table by sup-plying the missing information.

26. Density Using the formula for density evaluateif two samples with the same volume, butdifferent densities, will have the same mass.Give two sample calculations to support youranswer.

Density

Sample Mass Volume Density

3.0 g

1.2 g

4.5 g

125 g

195.6 g

7.5 g

A

B

C

D

E

F

6.5 cm3

1.1 cm3

5.1 cm3

347 cm3

85 cm3

10 cm3

0.46 g/cm3

1.9 g/cm3

0.88 g/cm3

0.36 g/cm3

2.3 g/cm3

0.75 g/cm3

Chapter Review fl6.msscience.com

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468 FLORIDA

a Making a cake involves mixing butter,eggs, sugar, and flour in a bowl and thenbaking the mixture. As the mixture bakes,the liquid turns brown and changes to asolid. Which step in the process of makinga cake results in a chemical change?

A. melting butter

B. baking the mixture

C. breaking egg shells

D. adding sugar and flour

s Pam and Reggie were asked to makeobservations of the bowling ball and kick-ball shown below.

Which is an observation they might havemade by looking at the two balls?

F. They have nearly equal masses.

G. They have nearly equal weights.

H. They have nearly equal volumes.

I. They have nearly equal densities.

Kickball

d Which is not a physical property of matter?

A. density

B. flammability

C. mass

D. volume

f Models can be used to compare the differ-ent states of matter. The diagram belowshows models of the three states of water(H2O).

What state of matter do the particles in jar A represent?

F. gas

G. liquid

H. plasma

I. solid

A B C

FloridaFloridachapter chapter

The assessed Florida Benchmark appears above each question.Record your answers on the answer sheet provided by your teacher or on a sheet of paper.

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g Which most likely describes a chemicalchange in a substance?

A. Frozen water melts and becomes a liquid.

B. A lump of clay is reshaped to becomea statue.

C. A nail exposed to water and airbecomes rusty.

D. Milk and chocolate syrup are mixed tomake a drink.

h When Ahmad heated mercury(II) oxide,HgO, liquid mercury (Hg) and oxygen(O2) were produced. The table belowshows some of the data from his experiment.

According to the law of conservation ofmass, what mass, in grams, of O2, is generated?

j A dry sponge has a mass of 60 grams (g).A moist sponge has a mass of 90 grams (g). The volume of each sponge is 180 cubic centimeters (cm3). Compareand contrast the densities of the twosponges.

k The graph below shows the relationship ofmass to volume for iron (Fe).

PART A According to the graph, whatare the mass and density of5.0 milliliters (mL) of iron?

PART B What is the mass of an ironsample that has a volume of9.0 mL? Explain your answer.

Iron Samples

15

30

10

2520

5

35

Volume (mL)

Mas

s (g

)

1 2 3 4 5

40

READINQUIREEXPLAIN

READINQUIREEXPLAIN

2HgO → 2Hg + O2

Beginning mass of HgO 216 grams

Mass of Hg after heating 200 grams

Mass of O2 after heating ? grams

FCAT PracticeFCAT Practice FC

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Relax Some people get nervous about tests. It’s natural. Justdo your best.


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