Section 3.1: Matter Section 3.2: Combining Matter Section 3.3: States of Matter Matter and Change 3

Objectives Describe an atom and its components. Relate energy levels of atoms to the chemical properties of elements. Define the concept of isotopes. Matter Section 3.1

Review Vocabulary atom: the smallest particle of an element that retains all the properties of that element Matter Atoms are the basic building blocks of all matter. Section 3.1

New Vocabulary matter element nucleus proton neutron Matter Section 3.1 electron atomic number mass number isotope ion

Atoms Matter is anything that has volume and mass. All matter is made of substances called elements. Matter Section 3.1

Atoms Matter Section 3.1 An element is a substance that cannot be broken down into simpler substances by physical or chemical means. Elements are made up of atoms.

Atoms All atoms consist of even smaller particles—protons, neutrons, and electrons. The center of an atom is called the nucleus, which is made up of protons and neutrons. Matter Section 3.1

Atoms A proton is a tiny particle that has mass and a positive electric charge. A neutron is a tiny particle with approximately the same mass as a proton, but it has no electrical charge. Matter Section 3.1

Atoms Surrounding the nucleus of an atom are electrons, smaller particles that are in constant motion. An electron has little mass, but it has a negative electric charge that is exactly the same magnitude as the positive charge of a proton. Matter Section 3.1

Atoms Matter Section 3.1 In this representation of an atom, the fuzzy area surrounding the nucleus is referred to as an electron cloud.

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Atoms Matter Section 3.1 The periodic table of the elements is arranged so that a great deal of information about all of the known elements is provided in a small space.

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Atoms Generally, each element is identified by a one-, two-, or three-letter abbreviation known as a chemical symbol. All elements are classified and arranged according to their chemical properties in the periodic table of the elements. Symbols for elements Matter Section 3.1

Atoms The number of protons in an atom’s nucleus is its atomic number. The sum of the protons and the neutrons in an atom’s nucleus is its mass number. Mass number Matter Section 3.1

Atoms This diagram of the element chlorine explains how atomic numbers and atomic mass are listed in the periodic table of the elements. Mass number Matter Section 3.1

Isotopes All atoms of an element have the same number of protons. However, the number of neutrons of an element’s atoms can vary. Atoms of the same element that have different mass numbers are called isotopes. Matter Section 3.1

Matter Section 3.1 Isotopes The atomic mass of an element is the average of the mass numbers of the isotopes of an element.

Matter Section 3.1 Isotopes Radioactive decay is the spontaneous process through which unstable nuclei emit radiation. In the process of radioactive decay, a nucleus can lose protons and neutrons, change a proton to a neutron, or change a neutron to a proton. Radioactive isotopes

Matter Section 3.1 Isotopes Because the number of protons in a nucleus identifies an element, decay can change the identity of an element. Radioactive isotopes

Matter Section 3.1 Electrons in Energy Levels Although the exact position of an electron cannot be determined, scientists have discovered that electrons occupy areas called energy levels.

Matter Section 3.1 Electrons in Energy Levels Electrons are distributed over one or more energy levels in a predictable pattern. Each energy level can hold only a limited number of electrons. Filling energy levels

Matter Section 3.1 Electrons in Energy Levels Electrons occupy one energy level in hydrogen, two energy levels in oxygen, and three energy levels in aluminum. Filling energy levels

Matter Section 3.1 Electrons in Energy Levels The electrons in the outermost energy level, called valence electrons, determine the chemical behavior of the different elements. Elements with the same number of valence electrons have similar chemical properties. Valence electrons

Matter Section 3.1 Electrons in Energy Levels Elements that have full outermost energy levels are highly unreactive, which means that they do not combine easily with other elements. Valence electrons

The inert nature of argon makes it an ideal gas to use inside an incandescent light bulb because it does not react with the extremely hot filament. Electrons in Energy Levels Valence electrons Matter Section 3.1

Matter Section 3.1 Ions An atom that gains or loses one or more electrons from its outermost energy level has a net electric charge and is called an ion.

Matter Section 3.1 Ions In general, an atom in which the outermost energy level is less than half-full—that is, it has fewer than four valence electrons—tends to lose its valence electrons and forms a positively charged ion.

Matter Section 3.1 Ions An atom in which the outermost energy level is more than half-full—that is, it has more than four valence electrons—tends to fill its outermost energy level and forms a negatively charged ion.

Matter Section 3.1 What elements are most abundant? The two most abundant elements in the universe are hydrogen and helium. However, the two most abundant elements in Earth’s crust are oxygen and silicon.

Objectives Describe the chemical bonds that unite atoms to form compounds. Relate the nature of chemical bonds that hold compounds together to the physical structures of compounds. Distinguish among different types of mixtures and solutions. Combining Matter Section 3.2

ion: an electrically charged atom Atoms combine through electric forces, forming molecules and compounds. Combining Matter Section 3.2 Review Vocabulary

New Vocabulary Combining Matter Section 3.2 compound chemical bond covalent bond molecule ionic bond metallic bond chemical reaction solution acid base

Compounds A compound is a substance that is composed of atoms of two or more different elements that are chemically combined. Compounds have different properties from the elements of which they are composed. Combining Matter Section 3.2

Compounds Compounds are represented by chemical formulas that include the symbol for each element followed by a subscript number showing the number of atoms of that element in the compound. Combining Matter Section 3.2 Chemical formulas

A state of stability is achieved by some elements by forming chemical bonds. A chemical bond is the force that holds together the elements in a compound. Combining Matter Section 3.2 Covalent Bonds

Combining Matter Section 3.2 The attraction of two atoms for a shared pair of electrons that holds the atoms together is called a covalent bond. Covalent Bonds

In this example, the nucleus of each atom has one proton with a positive charge. The two positively charged protons attract the two negatively charged electrons. Combining Matter Section 3.2 Covalent Bonds

A molecule is composed of two or more atoms held together by covalent bonds. A compound comprised of molecules is called a molecular compound. Covalent Bonds Combining Matter Section 3.2 Molecules

Covalent Bonds Molecules held together by covalent bonds may not share electrons equally, resulting in the electrons spending more time near one atom than another. This unequal sharing results in polar molecules. Combining Matter Section 3.2 Polar molecules

Combining Matter Section 3.2 Covalent Bonds A polar molecule has a slightly positive end and a slightly negative end. Polar molecules

Ionic Bonds An ionic bond is the attractive force between two ions of opposite charge. Compounds formed by ionic bonds are called ionic compounds. Combining Matter Section 3.2

Ionic Bonds A sodium atom tends to lose a single valence electron, and a chlorine atom tends to gain a single valence electron. An ionic bond is formed by the attraction between oppositely charged ions. Combining Matter Section 3.2

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Metallic Bonding In a metallic bond, the positive ions of the metal are held together by the attraction to the negative electrons moving among them. Combining Matter Section 3.2

Metallic Bonding Combining Matter Section 3.2 Metallic bonds allow metals to conduct electricity because some of the electrons move freely throughout the entire metal.

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Metallic Bonding When a force is applied to a metal, some of the electrons are pushed aside. This allows the metal ions to move past each other, thus deforming or changing the shape of the metal. Combining Matter Section 3.2

Visualizing Bonds Combining Matter Section 3.2 Atoms gain stability by sharing, gaining, or losing electrons to form ions and molecules. The properties of metals can be explained by metallic bonds.

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Chemical Reactions The change of one or more compounds into other compounds is called a chemical reaction. Chemical reactions are described by chemical equations. Combining Matter Section 3.2

Chemical Reactions Example Water is formed by the chemical reaction between hydrogen gas (H2) and oxygen gas (O2). Combining Matter Section 3.2

When you write a chemical equation, you must balance the equation by showing an equal number of atoms for each element on each side of the equation. Therefore, the same amount of matter is present both before and after the reaction. Combining Matter Section 3.2 Chemical Reactions

Mixtures and Solutions A mixture is a combination of two or more components that retain their identities. When a mixture’s components are easily recognizable, it is called a heterogeneous mixture. Combining Matter Section 3.2

Mixtures and Solutions Combining Matter Section 3.2 In a homogeneous mixture, also called a solution, the component particles cannot be distinguished, even though they still retain their original properties. A solution can be liquid, gaseous, or solid.

Mixtures and Solutions Acids An acid is a solution containing a substance that produces hydrogen ions (H+) in water. Combining Matter Section 3.2

Mixtures and Solutions Combining Matter Section 3.2 The pH scale is based on the amount of hydrogen ions in a solution. Acids

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Combining Matter Section 3.2 Mixtures and Solutions Bases When a solution produces hydroxide ions (OH–) in water, the solution is called a base.

Objectives Describe the states of matter on Earth. Explain the reasons that matter exists in these states. Relate the role of thermal energy to changes in states of matter. States of Matter Section 3.3

chemical reaction: the change of one or more substances into another substance Review Vocabulary All matter on Earth and in the universe occurs in the form of a solid, a liquid, a gas, or plasma. States of Matter Section 3.3

New Vocabulary States of Matter Section 3.3 crystalline structure glass evaporation plasma condensation sublimation

Solids States of Matter Section 3.3 Solids are substances with densely packed particles, which can be ions, atoms, or molecules.

States of Matter Section 3.3 Solids Most solids are crystalline structures because the particles of a solid are arranged in regular geometric patterns, giving solids definite shape and volume.

States of Matter Section 3.3 Solids Glass is a solid that consists of densely packed atoms arranged randomly.

Liquids States of Matter Section 3.3 An increase in temperature increases the thermal vibrations of atoms in a solid. When thermal vibrations become vigorous enough to break the forces holding the solid together, the particles can slide past each other, and the substance becomes liquid.

States of Matter Section 3.3 Liquids Liquids take the shape of the container they are placed in, but they do have a definite volume.

Gases Some vibrating particles can gain sufficient thermal energy to escape a liquid. This process of change from a liquid to a gas at temperatures below the boiling point is called evaporation. States of Matter Section 3.3

Gases States of Matter Section 3.3 Gases, like liquids, have no definite shape. Gases also have no definite volume unless they are restrained by a container or a force such as gravity.

Plasma States of Matter Section 3.3 At extreme temperatures, the collisions between particles in matter are so violent that electrons are knocked away from atoms, resulting in hot, highly ionized, electrically conducting gases called plasmas.

Changes of State Solids melt when they absorb enough thermal energy to cause their orderly internal crystalline arrangement to break down. This happens at the melting point. States of Matter Section 3.3

States of Matter Section 3.3 Changes of State When liquids are cooled, they solidify at that same temperature and release thermal energy. The temperature at which liquids solidify is called the freezing point.

States of Matter Section 3.3 Changes of State When a liquid is heated to the boiling point and absorbs enough thermal energy, vaporization occurs, and the liquid becomes a gas.

States of Matter Section 3.3 Changes of State When a gas is cooled to the boiling point, it releases thermal energy and becomes a liquid in a process called condensation.

The slow change of state from a solid to a gas without an intermediate liquid state is called sublimation. States of Matter Section 3.3 Changes of State

Conservation of Energy States of Matter Section 3.3 The fundamental fact that matter cannot be created or destroyed is called the law of conservation of matter.

States of Matter Section 3.3 Conservation of Energy Like matter, energy cannot be created or destroyed, but it can be changed from one form to another. This law, called the conservation of energy, is also known as the first law of thermodynamics.

Chapter Resource Menu Section Questions Chapter Assessment Questions Standardized Test Practice Earth Science Online Glencoe Earth Science Transparencies Image Bank Vocabulary Animations Click on a hyperlink to view the corresponding feature. Study Guide Matter and Change 3

Key Concepts Section 3.1 Matter Atoms are the basic building blocks of all matter. Atoms consist of protons, neutrons, and electrons. An element consists of atoms that have a specific number of protons in their nuclei. Study Guide 3

Isotopes of an element differ by the number of neutrons in their nuclei. Elements with a full outermost energy level are highly unreactive. Ions are electrically charged atoms or groups of atoms. Section 3.1 Matter 3 Study Guide Key Concepts

Atoms combine through electric forces, forming molecules and compounds. Atoms of different elements combine to form compounds. Covalent bonds form from shared electrons between atoms. Section 3.2 Combining Matter 3 Study Guide Key Concepts

Ionic compounds form from the attraction of positive and negative ions. There are two types of mixtures–heterogeneous and homogeneous. Acids are solutions containing hydrogen ions. Bases are solutions containing hydroxide ions. Section 3.2 Combining Matter 3 Study Guide Key Concepts

Key Concepts Section 3.3 States of Matter All matter on Earth and in the universe occurs in the form of a solid, a liquid, a gas, or plasma. Changes of state involve thermal energy. Study Guide 3

Key Concepts Section 3.3 States of Matter The law of conservation of matter states that matter cannot be created or destroyed. The law of conservation of energy states that energy is neither created nor destroyed. Study Guide 3

What forms as a neutral atom gains or loses an outer electron? a. an ion b. a proton c. a neutron d. an isotope 3.1 Section Questions Matter and Change 3

What information about potassium does the number 19 provide? a. the state of matter b. the mass number c. the atomic mass d. the atomic number 3.1 Section Questions Matter and Change 3

How does the abundance of elements in the universe compare with the abundance of elements in Earth’s crust? 3.1 Section Questions Matter and Change 3

3.1 Section Questions Matter and Change 3 Possible answer: The vast majority of matter in the universe consists of the elements hydrogen and helium. The remaining elements make up only a small proportion of the matter in the universe. Earth’s crust consists mostly of the elements oxygen and silicon. Hydrogen and helium are comparatively rare.

Beach sand consists of grains of minerals, rocks, and sometimes fossil fragments. Which term best describes beach sand? a. solution b. compound c. homogeneous mixture d. heterogeneous mixture 3.2 Section Questions Matter and Change 3

Which type of chemical bond forms between atoms or groups of atoms that have opposite charge? a. ionic bond b. covalent bond c. chemical bond d. metallic bond 3.2 Section Questions Matter and Change 3

Chemical reactions are often described by using a chemical equation. What information does a chemical equation provide? 3.2 Section Questions Matter and Change 3

3.2 Section Questions Matter and Change 3 Possible answer: A chemical equation gives each reactant and product in the reaction. It also provides information about the relative number of each reactant and product required for mass balance.

The particles in a solid vibrate in fixed position. a. true b. false 3.3 Section Questions Matter and Change 3

Which of the following occurs when a liquid freezes? a. Thermal energy is released. b. Thermal energy is absorbed. c. Particles move freely. d. Particles become ions. 3.3 Section Questions Matter and Change 3

Which term is used to describe solids that consist of a regular geometric pattern of particles? a. glass b. mineral c. crystalline structure d. rock 3.3 Section Questions Matter and Change 3

In which state does matter have a definite volume but not a definite shape? a. solid b. liquid c. gas d. plasma Chapter Assessment Questions Matter and Change 3

Four elements and the number of electrons surrounding a neutral atom of each element are listed below. Which element is least likely to form a chemical bond? a. nitrogen, 7 electrons b. oxygen, 8 electrons c. fluorine, 9 electrons d. neon, 10 electrons Chapter Assessment Questions Matter and Change 3

The calcium ion (Ca2+) and the magnesium ion (Mg2+) combine with the carbonate ion (CO32–) to form the common mineral dolomite. Which formula represents this mineral? a. CaMg(CO3)2 b. Ca2Mg2(CO3) c. CaMg(CO3) d. Ca2Mg(CO3)2 Chapter Assessment Questions Matter and Change 3

Metals, such as copper, are good conductors of electricity. What property of metals makes them good conductors? Chapter Assessment Questions Matter and Change 3

Answer: Bonding in metals occurs because positively charged atomic nuclei are surrounded by and attracted to negatively charged electrons. The electrons involved in this metallic bonding are free to move throughout the solid and carry electric current. Chapter Assessment Questions Matter and Change 3

A sealed jar contains water vapor, or gaseous water. The jar is cooled until liquid water condenses inside the jar. How does the weight of the jar after condensation compare to its weight before condensation? Chapter Assessment Questions Matter and Change 3

Answer: The jar has the same weight. Matter is conserved during any change of state. The amount of matter that is acted on by Earth’s gravity is the same whether the matter is gas or liquid. Chapter Assessment Questions Matter and Change 3

Which of the following examples is a solution? a. soil b. a rock c. salt water d. pure water Standardized Test Practice Matter and Change 3

Sodium has an atomic number of 11. What electric charge will common ions of sodium have? a. 1+ b. 1– c. 3+ d. 3– Standardized Test Practice Matter and Change 3

Some elements have more than one isotope. How do isotopes of the same element differ from one another? a. by the number of protons b. by the number of neutrons c. by the number of electrons d. by the number of energy levels Standardized Test Practice Matter and Change 3

a. 1 b. 2 c. 3 d. 4 This equation shows the dissolution of the mineral calcite. What number of bicarbonate ions is required in this equation to satisfy the law of conservation of mass? Standardized Test Practice Matter and Change 3 calcite carbonic acid bicarbonate ion calcium ion

The Sun’s corona is an example of matter in the plasma state. What is the plasma state of matter? Standardized Test Practice Matter and Change 3

Answer: At extremely high temperatures, particles in matter vibrate so violently that electrons are knocked away from atoms. The result is a gas that consists of positive ions and free electrons. Standardized Test Practice Matter and Change 3

Matter and Change 3 Glencoe Earth Science Transparencies

Matter and Change 3 Image Bank

Section 3.1 Vocabulary matter element nucleus proton neutron electron atomic number mass number isotope ion Matter and Change 3

Section 3.2 Vocabulary Matter and Change 3 compound chemical bond covalent bond molecule ionic bond metallic bond chemical reaction solution acid base

Section 3.3 Vocabulary crystalline structure glass evaporation plasma condensation sublimation Matter and Change 3

Electron Cloud Periodic Table of the Elements Ionic Bonds Electron Flow in a Wire Visualizing Bonds pH Scale Animations 3