2Topic 3: Matter—Properties and Change Table of ContentsTopic3Topic 3: Matter—Properties and ChangeBasic ConceptsAdditional Concepts
3Properties of Matter—Substances Matter—Properties and Change: Basic ConceptsTopic3Properties of Matter—SubstancesMatter that has a uniform and unchanging composition is called a substance, also known as a pure substance.Table salt is a substance.Another example of a pure substance is water.Water is always composed of hydrogen and oxygen.
4Properties of Matter—Substances Matter—Properties and Change: Basic ConceptsTopic3Properties of Matter—SubstancesSeawater, on the other hand, is not a substance because samples taken from different locations will probably have differing compositions.That is, they will contain differing amounts of water, salts, and other dissolved substances.
5Physical Properties of Matter Matter—Properties and Change: Basic ConceptsTopic3Physical Properties of MatterA physical property is a characteristic that can be observed or measured without changing the sample’s composition. Physical properties describe pure substances, too.Because substances have uniform and unchanging compositions, they have consistent and unchanging physical properties as well.
6Physical Properties of Matter Matter—Properties and Change: Basic ConceptsTopic3Physical Properties of MatterClick box to view movie clip.
7Physical Properties of Matter Matter—Properties and Change: Basic ConceptsTopic3Physical Properties of Matterdensity,taste,color,hardness,odor,melting point,and boiling point are common physical properties that scientists record as identifying characteristics of a substance.
8Extensive and Intensive Properties Matter—Properties and Change: Basic ConceptsTopic3Extensive and Intensive Properties Physical properties can be further described as being one of two types.Extensive properties are dependent upon the amount of substance present. For example, mass, which depends on the amount of substance there is, is an extensive property.Length and volume are also extensive properties.
9Extensive and Intensive Properties Matter—Properties and Change: Basic ConceptsTopic3Extensive and Intensive Properties Density, on the other hand, is an example of an intensive property of matter.Intensive properties are independent of the amount of substance present.For example, density of a substance (at constant temperature and pressure) is the same no matter how much substance is present.
10Chemical Properties of Matter Matter—Properties and Change: Basic ConceptsTopic3Chemical Properties of MatterThe ability of a substance to combine with or change into one or more other substances is called a chemical property.The ability of iron to form rust when combined with air is an example of a chemical property of ironSimilarly, the inability of a substance to change into another substance is also a chemical property.
11Chemical Properties of Matter Matter—Properties and Change: Basic ConceptsTopic3Chemical Properties of MatterFor example, when iron is placed in nitrogen gas at room temperature, no chemical change occurs.The fact that iron does not undergo a change in the presence of nitrogen is another chemical property of iron.
12Observing Properties of Matter Matter—Properties and Change: Basic ConceptsTopic3Observing Properties of MatterEvery substance has its own unique set of physical and chemical properties.Observations of properties may vary depending on the conditions of the immediate environment.It is important to state the specific conditions in which observations are made because both chemical and physical properties depend on temperature and pressure.
13Matter—Properties and Change: Basic Concepts Topic3States of MatterIn fact, all matter that exists on Earth can be classified as one of these physical forms called states of matter.Scientists recognize a fourth state of matter called plasma, but it does not occur naturally on Earth except in the form of lightning bolts.
14Matter—Properties and Change: Basic Concepts Topic3States of MatterThe physical state of a substance is a physical property of that substance.Each of the three common states of matter can be distinguished by the way it fills a container.
15Wood, iron, paper, and sugar are examples of solids. Matter—Properties and Change: Basic ConceptsTopic3SolidsA solid is a form of matter that has its own definite shape and volume.Wood, iron, paper, and sugar are examples of solids.
16Matter—Properties and Change: Basic Concepts Topic3SolidsThe particles of matter in a solid are very tightly packed; when heated, a solid expands, but only slightly.Because its shape is definite, a solid may not conform to the shape of the container in which it is placed.
17Common examples of liquids include water, blood, and mercury. Matter—Properties and Change: Basic ConceptsTopic3Liquids A liquid is a form of matter that flows, has constant volume, and takes the shape of its container.Common examples of liquids include water, blood, and mercury.The particles in a liquid are not rigidly held in place and are less closely packed than are the particles in a solid: liquid particles are able to move past each other.
18Matter—Properties and Change: Basic Concepts Topic3Liquids This allows a liquid to flow and take the shape of its container, although it may not completely fill the container.
19Matter—Properties and Change: Basic Concepts Topic3Liquids Because of the way the particles of a liquid are packed, liquids are virtually incompressible. Like solids, liquids tend to expand when heated.
20Matter—Properties and Change: Basic Concepts Topic3GasesA gas is a form of matter that flows to conform to the shape of its container and fills the entire volume of its container.Compared to solids and liquids, the particles of gases are very far apart.Because of the significant amount of space between particles, gases are easily compressed.
21Matter—Properties and Change: Basic Concepts Topic3GasesThe word gas refers to a substance that is naturally in the gaseous state at room temperature.The word vapor refers to the gaseous state of a substance that is a solid or a liquid at room temperature.For example, steam is a vapor because at room temperature water exists as a liquid.
22Matter—Properties and Change: Basic Concepts Topic3GasesThe fact that substances can change form, as in the example of water changing to steam, is another important concept in chemistryIf you review what you just learned about physical properties of substances, you can see that because the particular form of a substance is a physical property, changing the form introduces or adds another physical property to its list of characteristics.
23Matter—Properties and Change: Basic Concepts Topic3GasesIn fact, resources that provide tables of physical and chemical properties of substances, such as the CRC Handbook of Chemistry and Physics, generally include the physical properties of substances in all of the states in which they can exist.
24An example is the crumpling of a sheet of aluminum foil. Matter—Properties and Change: Basic ConceptsTopic3Physical ChangesA substance often undergoes changes that result in a dramatically different appearance yet leave the composition of the substance unchanged.An example is the crumpling of a sheet of aluminum foil.
25Matter—Properties and Change: Basic Concepts Topic3Physical ChangesWhile the foil goes from a smooth, flat, mirrorlike sheet to a round, compact ball, the actual composition of the foil is unchanged—it is still aluminumChanges such as this, which alter a substance without changing its composition, are known as physical changes.
26Matter—Properties and Change: Basic Concepts Topic3Physical ChangesAs with other physical properties, the state of matter depends on the temperature and pressure of the surroundings.As temperature and pressure change, most substances undergo a change from one state (or phase) to another.
27Matter—Properties and Change: Basic Concepts Topic3Physical ChangesMelting and formation of a gas are both physical changes and phase changes.When you encounter terms such as boil, freeze, condense, vaporize, or melt in your study of chemistry, the meaning generally refers to a phase change in matter.
28Matter—Properties and Change: Basic Concepts Topic3Chemical ChangesChemical properties relate to the ability of a substance to combine with or change into one or more substances.A process that involves one or more substances changing into new substances is called a chemical change, which is commonly referred to as a chemical reaction.
29Matter—Properties and Change: Basic Concepts Topic3Chemical ChangesThe new substances formed in the reaction have different compositions and different properties from the substances present before the reaction occurred.
30The iron reacts with oxygen in the air to form a new substance, rust. Matter—Properties and Change: Basic ConceptsTopic3Chemical ChangesWhen a freshly exposed iron surface is left in contact with air, it slowly changes into a new substance, namely, the rust.The iron reacts with oxygen in the air to form a new substance, rust.
31Rust is a chemical combination of iron and oxygen. Matter—Properties and Change: Basic ConceptsTopic3Chemical ChangesRust is a chemical combination of iron and oxygen.In chemical reactions, the starting substances are called reactants and the new substances that are formed are called products.
32Thus iron and oxygen are reactants and rust is a product. Matter—Properties and Change: Basic ConceptsTopic3Chemical ChangesThus iron and oxygen are reactants and rust is a product.When you encounter terms such as explode, rust, oxidize, corrode, tarnish, ferment, burn, or rot, the meaning generally refers to a chemical reaction in which reactant substances produce different product substances.
33Matter—Properties and Change: Basic Concepts Topic3Conservation of MassBy carefully measuring mass before and after many chemical reactions, it was observed that, although chemical changes occurred, the total mass involved in the reaction remained constant.The constancy of mass in chemical reactions was observed so often that scientists assumed the phenomenon must be true for all reactions.
34Conservation of Mass Topic 3 Matter—Properties and Change: Basic ConceptsTopic3Conservation of MassClick box to view movie clip.
35They summarized this observation in a scientific law. Matter—Properties and Change: Basic ConceptsTopic3Conservation of MassThey summarized this observation in a scientific law.The law of conservation of mass states that mass is neither created nor destroyed during a chemical reaction—it is conserved.This law was one of the great achievements of eighteenth-century science.
36The equation form of the law of conservation of mass is: Matter—Properties and Change: Basic ConceptsTopic3Conservation of MassThe equation form of the law of conservation of mass is:
37Matter—Properties and Change: Basic Concepts Topic3Conservation of MassLavoisier’s experimental decomposition of mercury(II) oxide is one proof of the law of conservation of mass.Although a chemical reaction is obvious, matter was neither created nor destroyed.The law of conservation of mass is one of the most fundamental concepts of chemistry.
38Basic Assessment Questions Topic3Question 1Identify each of the following as a property of a solid, liquid, or gas. Some answers will include more that one state of matter.
39A. flows and takes the shape of a container B. compressible Basic Assessment QuestionsTopic3A. flows and takes the shape of a containerB. compressibleC. made of particles held in a specificarrangementD. has definite volumeE. always occupies the entire space of itscontainerF. has a definite volume but flows
40Answers A. flows and takes the liquid, gas shape of a container Basic Assessment QuestionsTopic3AnswersA. flows and takes theshape of a containerliquid, gasB. compressiblegasC. made of particlesheld in a specificarrangementsolid
41Answers D. has definite volume solid, liquid E. always occupies the Basic Assessment QuestionsTopic3AnswersD. has definite volumesolid, liquidE. always occupies theentire space of itscontainergasF. has a definite volumebut flowsliquid
42Basic Assessment Questions Topic3Question 2Identify each of the following as an example of a chemical change or a physical change.Moisture in the air forms beads of wateron a cold windowpane.B. An electric current changes water intohydrogen and oxygen.C. Yeast cells in bread dough make carbondioxide an ethanol from sugar.
43Answers Moisture in the air forms beads of water on a cold windowpane. Basic Assessment QuestionsTopic3AnswersMoisture in the air forms beadsof water on a cold windowpane.PhysicalB. An electric current changeswater into hydrogen andoxygen.ChemicalC. Moisture in the air forms beadsof water on a cold windowpane.Chemical
44Basic Assessment Questions Topic3Question 3A reaction between sodium hydroxide and hydrogen chloride gas produces sodium chloride and water. A reaction of g of sodium hydroxide with g of hydrogen chloride gives off g of water. What mass of sodium chloride is formed in the reaction?
45Basic Assessment Questions Topic3Answer33.38 g sodium chloride
46Additional Concepts Topic 3 Matter—Properties and Change: Additional ConceptsTopic3Additional Concepts
47Matter—Properties and Change: Additional Concepts Topic3MixturesA mixture is a combination of two or more pure substances in which each pure substance retains its individual chemical properties.The composition of mixtures is variable, and the number of mixtures that can be created by combining substances is infinite.
48Substances tend naturally to mix; it is difficult to keep things pure. Matter—Properties and Change: Additional ConceptsTopic3MixturesAlthough much of the focus of chemistry is the behavior of substances, it is important to remember that most everyday matter occurs as mixtures.Substances tend naturally to mix; it is difficult to keep things pure.
49Two mixtures, sand and water, and table salt and water, are shown. Matter—Properties and Change: Additional ConceptsTopic3MixturesTwo mixtures, sand and water, and table salt and water, are shown.You know water to be a colorless liquid.
50Sand is a grainy solid that does not dissolve in water. Matter—Properties and Change: Additional ConceptsTopic3MixturesSand is a grainy solid that does not dissolve in water.When sand and water are mixed, the two substances are in contact, yet each substance retains its properties.
51The sand and water have not reacted. Matter—Properties and Change: Additional ConceptsTopic3MixturesThe sand and water have not reacted.Just by looking at the sand–water mixture in beaker A, it is easy to see each separate substance.
52Some mixtures, however, may not look like mixtures at all. Matter—Properties and Change: Additional ConceptsTopic3MixturesSome mixtures, however, may not look like mixtures at all.The mixture of table salt and water in the beaker labeled B is colorless and appears the same as pure water.How can you determine if it is a mixture?
53Matter—Properties and Change: Additional Concepts Topic3MixturesIf you were to boil away the water, you would see a white residue. That residue is the salt. Thus, the colorless mixture actually contained two separate substances.
54Matter—Properties and Change: Additional Concepts Topic3MixturesThe salt and the water physically mixed but did not react and were separated by the physical method of boiling.
55The sand and water mixture is an example of a heterogeneous mixture. Matter—Properties and Change: Additional ConceptsTopic3Types of MixturesMixtures themselves are classified as either heterogeneous or homogeneous.A heterogeneous mixture is one that does not blend smoothly throughout and in which the individual substances remain distinct.The sand and water mixture is an example of a heterogeneous mixture.
56The drop would be almost completely water. Matter—Properties and Change: Additional ConceptsTopic3Types of MixturesSuppose you draw a drop from the top of the mixture using an eyedropper.The drop would be almost completely water.
57Matter—Properties and Change: Additional Concepts Topic3Types of MixturesIf you draw a second drop from the bottom of the mixture, that drop would contain mostly sand.Thus the composition of the sand–water mixture is not uniform—the substances have not blended smoothly and the two substances of the mixture (sand on the bottom and water on the top) remain distinct.
58Let’s examine the salt–water mixture using the eyedropper. Matter—Properties and Change: Additional ConceptsTopic3Types of MixturesA homogeneous mixture has constant composition throughout; it always has a single phase.Let’s examine the salt–water mixture using the eyedropper.A drop of the mixture from the top of the beaker has the same composition as a drop from the bottom of the beaker. In fact, every drop of the mixture contains the same relative amounts of salt and water.
59Homogeneous mixtures are also referred to as solutions. Matter—Properties and Change: Additional ConceptsTopic3Types of MixturesHomogeneous mixtures are also referred to as solutions.
60You are probably most familiar with solutions in a liquid form, Matter—Properties and Change: Additional ConceptsTopic3Types of MixturesYou are probably most familiar with solutions in a liquid form,such as cough suppressant medicine and lemonade, but solutions may contain solids, liquids, or gases.
61The solid–solid solution known as steel is called an alloy. Matter—Properties and Change: Additional ConceptsTopic3Types of MixturesThe solid–solid solution known as steel is called an alloy.An alloy is a homogeneous mixture of metals, or a mixture of a metal and a nonmetal in which the metal substance is the major component.
62Most matter exists naturally as mixtures. Matter—Properties and Change: Additional ConceptsTopic3Separating MixturesMost matter exists naturally as mixtures.Because the substances in a mixture are physically combined, the processes used to separate a mixture are physical processes that are based on the difference in physical properties of the substances.Sometimes it is very easy to separate a mixture; separating a mixture of pennies and nickels is not a difficult task.
63Matter—Properties and Change: Additional Concepts Topic3Separating MixturesHeterogeneous mixtures composed of solids and liquids are easily separated by filtration.Filtration is a technique that uses a porous barrier to separate a solid from a liquid.
64Most homogeneous mixtures can be separated by distillation Matter—Properties and Change: Additional ConceptsTopic3Separating MixturesMost homogeneous mixtures can be separated by distillationDistillation is a separation technique that is based on differences in the boiling points of the substances involved.
65Matter—Properties and Change: Additional Concepts Topic3Separating MixturesWhen precisely controlled, distillation can separate substances having boiling points that differ by only a few degrees.
66Matter—Properties and Change: Additional Concepts Topic3Separating MixturesCrystallization is a separation technique that results in the formation of pure solid particles of a substance from a solution containing the dissolved substance.
67Matter—Properties and Change: Additional Concepts Topic3Separating MixturesChromatography is a technique that separates the components of a mixture (called the mobile phase) on the basis of the tendency of each to travel or be drawn across the surface of another material (called the stationary phase).The separation occurs because the various components of the ink spread through the paper ant different rates.
68Matter—Properties and Change: Additional Concepts Topic3ElementsAll matter can be broken down into a relatively small number of basic building blocks called elements.An element is a pure substance that cannot be separated into simpler substances by physical or chemical means.
69Each element has a unique chemical name and symbol. Matter—Properties and Change: Additional ConceptsTopic3ElementsEach element has a unique chemical name and symbol.The chemical symbol consists of one, two, or three letters; the first letter is always capitalized and the remaining letter(s) are always lowercase.
70Matter—Properties and Change: Additional Concepts Topic3ElementsThe names and symbols of the elements are universally accepted by scientists in order to make the communication of chemical information possible.
71Matter—Properties and Change: Additional Concepts Topic3ElementsAs many new elements were being discovered in the early nineteenth century, chemists began to see patterns of similarities in the chemical and physical properties of particular sets of elements.Several schemes for organizing the elements on the basis of these similarities were proposed, with varying degrees of success.
72Matter—Properties and Change: Additional Concepts Topic3ElementsIn 1869, the Russian chemist Dmitri Mendeleev made a significant contribution to the effort. Mendeleev devised the chart which organized all of the elements that were known at the time into rows and columns based on their similarities and their masses.
73Matter—Properties and Change: Additional Concepts Topic3ElementsMendeleev’s organizational table was the first version of what has been further developed into the periodic table of elements.The periodic table organizes the elements into a grid of horizontal rows called periods and vertical columns called groups or families.Elements in the same group have similar chemical and physical properties.
74Matter—Properties and Change: Additional Concepts Topic3ElementsElements in the same group have similar chemical and physical properties.The table is called “periodic” because the pattern of similar properties repeats as you move from period to period.
75Matter—Properties and Change: Additional Concepts Topic3Periodic Table
76You know that matter is classified as pure substances and mixtures. Matter—Properties and Change: Additional ConceptsTopic3CompoundsYou know that matter is classified as pure substances and mixtures.You also know that elements are pure substances that cannot be separated into simpler substances.There is yet another classification of pure substances—compounds.
77Matter—Properties and Change: Additional Concepts Topic3CompoundsA compound is a combination of two or more different elements that are combined chemically.Most of the substances that you are familiar with and, in fact, much of the matter of the universe are compounds.Water, table salt, table sugar, and aspirin are examples of common compounds.
78Matter—Properties and Change: Additional Concepts Topic3CompoundsToday, there are approximately 10 million known compounds, and new compounds continue to be developed and discovered at the rate of about per year.
79Matter—Properties and Change: Additional Concepts Topic3CompoundsThere appears to be no limit to the number of compounds that can be made or that will be discovered.Considering this virtually limitless potential, several organizations have assumed the task of collecting data and indexing the known chemical compounds.
80Matter—Properties and Change: Additional Concepts Topic3CompoundsThese organizations maintain huge databases that allow researchers to access information on existing compounds.The databases and retrieval tools enable scientists to build the body of chemical knowledge in an efficient manner.
81Categories of Matter Topic 3 Matter—Properties and Change: Additional ConceptsTopic3Categories of Matter
82Matter—Properties and Change: Additional Concepts Topic3CompoundsThe chemical symbols of the periodic table make it easy to write the formulas for chemical compounds.For example, table salt, or sodium chloride, is composed of one part sodium (Na) and one part chlorine (Cl), and its chemical formula is NaCl.Water is composed of two parts hydrogen (H) to one part oxygen (O), and its formula is H2O.
83Matter—Properties and Change: Additional Concepts Topic3CompoundsUnlike elements, compounds can be broken down into simpler substances by chemical means.In general, compounds that naturally occur are more stable than the individual component elements.To separate a compound into its elements often requires external energy such as heat or electricity.
84Water is a stable compound that is liquid at room temperature. Matter—Properties and Change: Additional ConceptsTopic3CompoundsThe properties of a compound are different from those of its component elements. The example of water illustrates this fact.Water is a stable compound that is liquid at room temperature.
85Matter—Properties and Change: Additional Concepts Topic3CompoundsWhen water is broken down into its components, it is obvious that hydrogen and oxygen are dramatically different than the liquid they form when combined.Oxygen and hydrogen are tasteless, odorless gases that vigorously undergo chemical reactions with many elements.
86Law of Definite Proportions Matter—Properties and Change: Additional ConceptsTopic3Law of Definite ProportionsAn important characteristic of compounds is that the elements comprising them combine in definite proportions by mass.This observation is so fundamental that it is summarized as the law of definite proportions.This law states that, regardless of the amount, a compound is always composed of the same elements in the same proportion by mass.
87Law of Definite Proportions Matter—Properties and Change: Additional ConceptsTopic3Law of Definite ProportionsThe mass of the compound is equal to the sum of the masses of the elements that make up the compound.The ratio of the mass of each element to the total mass of the compound is a percentage called the percent by mass.
88Law of Multiple Proportions Matter—Properties and Change: Additional ConceptsTopic3Law of Multiple ProportionsThe law of multiple proportions states that when different compounds are formed by a combination of the same elements, different masses of one element combine with the same relative mass of the other element in a ratio of small whole numbers.Ratios compare the relative amounts of any items or substances.
89Law of Multiple Proportions Matter—Properties and Change: Additional ConceptsTopic3Law of Multiple ProportionsThe comparison can be expressed using numbers separated by a colon or as a fraction.With regard to the law of multiple proportions, ratios express the relationship of elements in a compound.
90Law of Multiple Proportions Matter—Properties and Change: Additional ConceptsTopic3Law of Multiple ProportionsThe two distinct compounds water (H2O) and hydrogen peroxide (H2O2) illustrate the law of multiple proportions.Each compound contains the same elements (hydrogen and oxygen).Water is composed of two parts hydrogen (the element that is present in different amounts in both compounds).
91Law of Multiple Proportions Matter—Properties and Change: Additional ConceptsTopic3Law of Multiple ProportionsHydrogen peroxide is composed of two parts hydrogen and two parts oxygen.Hydrogen peroxide differs from water in that it has twice as much oxygen.When we compare the mass of oxygen in hydrogen peroxide to the mass of oxygen in water, we get the ratio 2:1.
92Law of Multiple Proportions Matter—Properties and Change: Additional ConceptsTopic3Law of Multiple ProportionsConsidering that there is a finite number of elements that exist today and an exponentially greater number of compounds that are composed of these elements under various conditions, it becomes clear how important the law of multiple proportions is in chemistry.
93Additional Assessment Questions Topic3Question 1Identify each of the following as an example of a homogeneous mixture or a heterogeneous mixture.
9470% isopropyl rubbing alcohol Additional Assessment QuestionsTopic370% isopropyl rubbing alcoholB. a pile of rusty iron filingsC. concreteD. saltwaterE. gasolineF. bread
95Answers 70% isopropyl rubbing homogeneous alcohol Additional Assessment QuestionsTopic3Answers70% isopropyl rubbingalcoholhomogeneousB. a pile of rusty iron filingsheterogeneousC. concreteheterogeneousD. saltwaterhomogeneousE. gasolinehomogeneousF. breadheterogeneous
96Additional Assessment Questions Topic3Question 2Identify each of the following as an example of an element or a compound.A. sucrose (table sugar)B. the helium in a balloonC. baking sodaD. a diamond
97Answers A. sucrose (table sugar) compound B. the helium in a balloon Additional Assessment QuestionsTopic3AnswersA. sucrose (table sugar)compoundB. the helium in a balloonelementC. baking sodacompoundD. a diamondelement
98Additional Assessment Questions Topic3Question 3A g sample of aspirin is made up of 6.03 g of hydrogen, g of carbon, and g of oxygen. What is the percent by mass of each element in aspirin?
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