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Introductory Chemistry - 1st Canadian Edition: Some Basic Definitions

Introductory Chemistry - 1st Canadian Edition
Some Basic Definitions
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table of contents
  1. Cover
  2. Title Page
  3. Copyright
  4. Table Of Contents
  5. Acknowledgments
  6. Dedication
  7. About BCcampus Open Education
  8. Chapter 1. What is Chemistry
    1. Some Basic Definitions
    2. Chemistry as a Science
  9. Chapter 2. Measurements
    1. Expressing Numbers
    2. Significant Figures
    3. Converting Units
    4. Other Units: Temperature and Density
    5. Expressing Units
    6. End-of-Chapter Material
  10. Chapter 3. Atoms, Molecules, and Ions
    1. Acids
    2. Ions and Ionic Compounds
    3. Masses of Atoms and Molecules
    4. Molecules and Chemical Nomenclature
    5. Atomic Theory
    6. End-of-Chapter Material
  11. Chapter 4. Chemical Reactions and Equations
    1. The Chemical Equation
    2. Types of Chemical Reactions: Single- and Double-Displacement Reactions
    3. Ionic Equations: A Closer Look
    4. Composition, Decomposition, and Combustion Reactions
    5. Oxidation-Reduction Reactions
    6. Neutralization Reactions
    7. End-of-Chapter Material
  12. Chapter 5. Stoichiometry and the Mole
    1. Stoichiometry
    2. The Mole
    3. Mole-Mass and Mass-Mass Calculations
    4. Limiting Reagents
    5. The Mole in Chemical Reactions
    6. Yields
    7. End-of-Chapter Material
  13. Chapter 6. Gases
    1. Pressure
    2. Gas Laws
    3. Other Gas Laws
    4. The Ideal Gas Law and Some Applications
    5. Gas Mixtures
    6. Kinetic Molecular Theory of Gases
    7. Molecular Effusion and Diffusion
    8. Real Gases
    9. End-of-Chapter Material
  14. Chapter 7. Energy and Chemistry
    1. Formation Reactions
    2. Energy
    3. Stoichiometry Calculations Using Enthalpy
    4. Enthalpy and Chemical Reactions
    5. Work and Heat
    6. Hess’s Law
    7. End-of-Chapter Material
  15. Chapter 8. Electronic Structure
    1. Light
    2. Quantum Numbers for Electrons
    3. Organization of Electrons in Atoms
    4. Electronic Structure and the Periodic Table
    5. Periodic Trends
    6. End-of-Chapter Material
  16. Chapter 9. Chemical Bonds
    1. Lewis Electron Dot Diagrams
    2. Electron Transfer: Ionic Bonds
    3. Covalent Bonds
    4. Other Aspects of Covalent Bonds
    5. Violations of the Octet Rule
    6. Molecular Shapes and Polarity
    7. Valence Bond Theory and Hybrid Orbitals
    8. Molecular Orbitals
    9. End-of-Chapter Material
  17. Chapter 10. Solids and Liquids
    1. Properties of Liquids
    2. Solids
    3. Phase Transitions: Melting, Boiling, and Subliming
    4. Intermolecular Forces
    5. End-of-Chapter Material
  18. Chapter 11. Solutions
    1. Colligative Properties of Solutions
    2. Concentrations as Conversion Factors
    3. Quantitative Units of Concentration
    4. Colligative Properties of Ionic Solutes
    5. Some Definitions
    6. Dilutions and Concentrations
    7. End-of-Chapter Material
  19. Chapter 12. Acids and Bases
    1. Acid-Base Titrations
    2. Strong and Weak Acids and Bases and Their Salts
    3. Brønsted-Lowry Acids and Bases
    4. Arrhenius Acids and Bases
    5. Autoionization of Water
    6. Buffers
    7. The pH Scale
    8. End-of-Chapter Material
  20. Chapter 13. Chemical Equilibrium
    1. Chemical Equilibrium
    2. The Equilibrium Constant
    3. Shifting Equilibria: Le Chatelier’s Principle
    4. Calculating Equilibrium Constant Values
    5. Some Special Types of Equilibria
    6. End-of-Chapter Material
  21. Chapter 14. Oxidation and Reduction
    1. Oxidation-Reduction Reactions
    2. Balancing Redox Reactions
    3. Applications of Redox Reactions: Voltaic Cells
    4. Electrolysis
    5. End-of-Chapter Material
  22. Chapter 15. Nuclear Chemistry
    1. Units of Radioactivity
    2. Uses of Radioactive Isotopes
    3. Half-Life
    4. Radioactivity
    5. Nuclear Energy
    6. End-of-Chapter Material
  23. Chapter 16. Organic Chemistry
    1. Hydrocarbons
    2. Branched Hydrocarbons
    3. Alkyl Halides and Alcohols
    4. Other Oxygen-Containing Functional Groups
    5. Other Functional Groups
    6. Polymers
    7. End-of-Chapter Material
  24. Chapter 17. Kinetics
    1. Factors that Affect the Rate of Reactions
    2. Reaction Rates
    3. Rate Laws
    4. Concentration–Time Relationships: Integrated Rate Laws
    5. Activation Energy and the Arrhenius Equation
    6. Reaction Mechanisms
    7. Catalysis
    8. End-of-Chapter Material
  25. Chapter 18. Chemical Thermodynamics
    1. Spontaneous Change
    2. Entropy and the Second Law of Thermodynamics
    3. Measuring Entropy and Entropy Changes
    4. Gibbs Free Energy
    5. Spontaneity: Free Energy and Temperature
    6. Free Energy under Nonstandard Conditions
    7. End-of-Chapter Material
  26. Appendix A: Periodic Table of the Elements
  27. Appendix B: Selected Acid Dissociation Constants at 25°C
  28. Appendix C: Solubility Constants for Compounds at 25°C
  29. Appendix D: Standard Thermodynamic Quantities for Chemical Substances at 25°C
  30. Appendix E: Standard Reduction Potentials by Value
  31. Glossary
  32. About the Authors
  33. Versioning History

Some Basic Definitions

Learning Objectives

  1. Learn the basic terms used to describe matter.

The definition of chemistry—the study of the interactions of matter with other matter and with energy—uses some terms that should also be defined. We start the study of chemistry by defining some basic terms.

Matter. A book is matter, a computer is matter, food is matter, and dirt in the ground is matter. Sometimes matter may be difficult to identify. For example, air is matter, but because it is so thin compared to other matter (e.g., a book, a computer, food, and dirt), we sometimes forget that air has mass and takes up space. Things that are not matter include thoughts, ideas, emotions, and hopes.

Example 1.1

Problems

Which of the following is matter and not matter?

  1. a hot dog
  2. love
  3. a tree

Solutions

  1. A hot dog has mass and takes up space, so it is matter.
  2. Love is an emotion, and emotions are not matter.
  3. A tree has mass and takes up space, so it is matter.

Test Yourself

Which of the following is matter and not matter?

  1. the moon
  2. an idea for a new invention

Answers

  1. The moon is matter.
  2. The invention itself may be matter, but the idea for it is not.
Ice cubes; glass of water; steaming kettle.
Figure 1.1 “The Phases of Matter.” Chemistry recognizes three fundamental phases of matter: solid (left), liquid (middle), and gas (right).

To understand matter and how it changes, we need to be able to describe matter. There are two basic ways to describe matter: physical properties and chemical properties. Physical properties are characteristics that describe matter as it exists. Some of many physical characteristics of matter are shape, color, size, and temperature. An important physical property is the phase (or state) of matter. The three fundamental phases of matter are solid, liquid, and gas (see Figure 1.1 “The Phases of Matter”).

A burning match, held beside a matchbox.
Figure 1.2 “Chemical Properties.” The fact that this match burns is a chemical property of the match.

Chemical properties are characteristics of matter that describe how matter changes form in the presence of other matter. Does a sample of matter burn? Burning is a chemical property. Does it behave violently when put in water? This reaction is a chemical property as well (Figure 1.2 “Chemical Properties”). In the following chapters, we will see how descriptions of physical and chemical properties are important aspects of chemistry.

Ice cubes melting into a puddle.
Figure 1.3 “Physical Changes.” The solid ice melts into liquid water—a physical change.

If matter always stayed the same, chemistry would be rather boring. Fortunately, a major part of chemistry involves change. A physical change occurs when a sample of matter changes one or more of its physical properties. For example, a solid may melt (Figure 1.3 “Physical Changes”), or alcohol in a thermometer may change volume as the temperature changes. A physical change does not affect the chemical composition of matter. A chemical change is the process of demonstrating a chemical property, such as the burning match in Figure 1.2 “Chemical Properties”. As the matter in the match burns, its chemical composition changes, and new forms of matter with new physical properties are created. Note that chemical changes are frequently accompanied by physical changes, as the new matter will likely have different physical properties from the original matter.

Example 1.2

Problems

Describe each process as a physical change or a chemical change.

  1. Water in the air turns into snow.
  2. A person’s hair is cut.
  3. Bread dough becomes fresh bread in an oven.

Solutions

  1. Because the water is going from a gas phase to a solid phase, this is a physical change.
  2. Your long hair is being shortened. This is a physical change.
  3. Because of the oven’s temperature, chemical changes are occurring in the bread dough to make fresh bread. These are chemical changes. (In fact, a lot of cooking involves chemical changes.)

Test Yourself

Identify each process as a physical change or a chemical change.

  1. A fire is raging in a fireplace.
  2. Water is warmed to make a cup of coffee.

Answers

  1. chemical change
  2. physical change

A sample of matter that has the same physical and chemical properties throughout is called a substance. Sometimes the phrase pure substance is used, but the word pure isn’t needed. The definition of the term substance is an example of how chemistry has a specific definition for a word that is used in everyday language with a different, vaguer definition. Here, we will use the term substance with its strict chemical definition.

Chemistry recognizes two different types of substances: elements and compounds. An element is the simplest type of chemical substance; it cannot be broken down into simpler chemical substances by ordinary chemical means. There are about 115 elements known to science, of which 80 are stable. (The other elements are radioactive, a condition we will consider in Chapter 15 “Nuclear Chemistry”.) Each element has its own unique set of physical and chemical properties. Examples of elements include iron, carbon, and gold.

A compound is a combination of more than one element. The physical and chemical properties of a compound are different from the physical and chemical properties of its constituent elements; that is, it behaves as a completely different substance. There are over 50 million compounds known, and more are being discovered daily. Examples of compounds include water, penicillin, and sodium chloride (the chemical name for common table salt).

Elements and compounds are not the only ways in which matter can be present. We frequently encounter objects that are physical combinations of more than one element or compound. Physical combinations of more than one substance are called mixtures. There are two types of mixtures. A heterogeneous mixture is a mixture composed of two or more substances. It is easy to tell, sometimes by the naked eye, that more than one substance is present. A homogeneous mixture is a combination of two or more substances that is so intimately mixed that the mixture behaves as a single substance. Another word for a homogeneous mixture is solution. Thus, a combination of salt and steel wool is a heterogeneous mixture because it is easy to see which particles of the matter are salt crystals and which are steel wool. On the other hand, if you take salt crystals and dissolve them in water, it is very difficult to tell that you have more than one substance present just by looking—even if you use a powerful microscope. The salt dissolved in water is a homogeneous mixture, or a solution (Figure 1.4 “Types of Mixtures”).

Flour and cocoa mixture (heterogeneous mixture); salt dissolved in water (homogeneous).
Figure 1.4 “Types of Mixtures.” On the left, the combination of two substances is a heterogeneous mixture because the particles of the two components look different. On the right, the salt crystals have dissolved in the water so finely that you cannot tell that salt is present. The homogeneous mixture appears like a single substance.

Example 1.3

Problems

Identify the following combinations as heterogeneous mixtures or homogenous mixtures.

  1. soda water (Carbon dioxide is dissolved in water.)
  2. a mixture of iron metal filings and sulfur powder (Both iron and sulfur are elements.)

Solutions

  1. Because carbon dioxide is dissolved in water, we can infer from the behaviour of salt crystals dissolved in water that carbon dioxide dissolved in water is (also) a homogeneous mixture.
  2. Assuming that the iron and sulfur are simply mixed together, it should be easy to see what is iron and what is sulfur, so this is a heterogeneous mixture.

Test Yourself

Are the following combinations homogeneous mixtures or heterogeneous mixtures?

  1. the human body
  2. an amalgam, a combination of some other metals dissolved in a small amount of mercury

Answers

  1. heterogeneous mixture
  2. homogeneous mixture

There are other descriptors that we can use to describe matter, especially elements. We can usually divide elements into metals and nonmetals, and each set shares certain (but not always all) properties. A metal is an element that is solid at room temperature (although mercury is a well-known exception), is shiny and silvery, conducts electricity and heat well, can be pounded into thin sheets (a property called malleability), and can be drawn into thin wires (a property called ductility). A nonmetal is an element that is brittle when solid, does not conduct electricity or heat very well, and cannot be made into thin sheets or wires (Figure 1.5 “Semimetals”). Nonmetals also exist in a variety of phases and colors at room temperature. Some elements have properties of both metals and nonmetals and are called semimetals (or metalloids). We will see later how these descriptions can be assigned rather easily to various elements.

Liquid mercury in a Petri dish; powdered yellow sulfur at the opening of a volcano.
Figure 1.5 “Semimetals.” On the left is some elemental mercury, the only metal that exists as a liquid at room temperature. It has all the other expected properties of a metal. On the right, elemental sulfur is a yellow nonmetal that usually is found as a powder.

Figure 1.6 “Describing Matter” is a flowchart of the relationships among the different ways of describing matter.

Flowchart describing matter.
Figure 1.6 “Describing Matter.” This flowchart shows how matter can be described.

Chemistry Is Everywhere: In the Morning

Most people have a morning ritual, a process that they go through every morning to get ready for the day. Chemistry appears in many of these activities.

  • If you take a shower or bath in the morning, you probably use soap, shampoo, or both. These items contain chemicals that interact with the oil and dirt on your body and hair to remove them and wash them away. Many of these products also contain chemicals that make you smell good; they are called fragrances.
  • When you brush your teeth in the morning, you usually use toothpaste, a form of soap, to clean your teeth. Toothpastes typically contain tiny, hard particles called abrasives that physically scrub your teeth. Many toothpastes also contain fluoride, a substance that chemically interacts with the surface of the teeth to help prevent cavities.
  • Perhaps you take vitamins, supplements, or medicines every morning. Vitamins and other supplements contain chemicals your body needs in small amounts to function properly. Medicines are chemicals that help combat diseases and promote health.
  • Perhaps you make some fried eggs for breakfast. Frying eggs involves heating them enough so that a chemical reaction occurs to cook the eggs.
  • After you eat, the food in your stomach is chemically reacted so that the body (mostly the intestines) can absorb food, water, and other nutrients.
  • If you drive or take the bus to school or work, you are using a vehicle that probably burns gasoline, a material that burns fairly easily and provides energy to power the vehicle. Recall that burning is a chemical change.

These are just a few examples of how chemistry impacts your everyday life. And we haven’t even made it to lunch yet!

Colourful shampoo bottles; a full English breakfast; a highway.
Figure 1.7 “Chemistry in Real Life.” Examples of chemistry can be found everywhere—such as in personal hygiene products, food, and motor vehicles.

View the video “The Chemical World” by Dr. Jessie A. Key for an introduction to the science of chemistry and how it fits into our everyday lives.

Key Takeaways

  • Chemistry is the study of matter and its interactions with other matter and energy.
  • Matter is anything that has mass and takes up space.
  • Matter can be described in terms of physical properties and chemical properties.
  • Physical properties and chemical properties of matter can change.
  • Matter is composed of elements and compounds.
  • Combinations of different substances are called mixtures.
  • Elements can be described as metals, nonmetals, and semimetals.

Exercises

Questions

  1. Identify each as either matter or not matter.
    1. a book
    2. hate
    3. light
    4. a car
    5. a fried egg
  2. Give an example of matter in each phase: solid, liquid, or gas.
  3. Does each statement represent a physical property or a chemical property?
    1. Sulfur is yellow.
    2. Steel wool burns when ignited by a flame.
    3. A gallon of milk weighs over eight pounds.
  4. Does each statement represent a physical property or a chemical property?
    1. A pile of leaves slowly rots in the backyard.
    2. In the presence of oxygen, hydrogen can interact to make water.
    3. Gold can be stretched into very thin wires.
  5. Does each statement represent a physical change or a chemical change?
    1. Water boils and becomes steam.
    2. Food is converted into usable form by the digestive system.
    3. The alcohol in many thermometers freezes at about −40 degrees Fahrenheit.
  6. Does each statement represent a physical change or a chemical change?
    1. Graphite, a form of elemental carbon, can be turned into diamond, another form of carbon, at very high temperatures and pressures.
    2. The house across the street has been painted a new colour.
    3. The elements sodium and chlorine come together to make a new substance called sodium chloride.
  7. Distinguish between an element and a compound. About how many of each are known?
  8. What is the difference between a homogeneous mixture and a heterogeneous mixture?
  9. Identify each as a heterogeneous mixture or a homogeneous mixture.
    1. Salt is mixed with pepper.
    2. Sugar is dissolved in water.
    3. Pasta is cooked in boiling water.
  10. Identify each as a heterogeneous mixture or a homogeneous mixture.
    1. air
    2. dirt
    3. a television set
  11. In Exercise 9, which choices are also solutions?
  12. In Exercise 10, which choices are also solutions?
  13. Why is iron considered a metal?
  14. Why is oxygen considered a nonmetal?
  15. Distinguish between a metal and a nonmetal.
  16. What properties do semimetals have?
  17. Elemental carbon is a black, dull-looking solid that conducts heat and electricity well. It is very brittle and cannot be made into thin sheets or long wires. Of these properties, how does carbon behave as a metal? How does carbon behave as a nonmetal?
  18. Pure silicon is shiny and silvery but does not conduct electricity or heat well. Of these properties, how does silicon behave as a metal? How does silicon behave as a nonmetal?

Answers

    1. matter
    2. not matter
    3. not matter
    4. matter
    1. physical property
    2. chemical property
    3. physical property
    1. physical change
    2. chemical change
    3. physical change
  1. An element is a fundamental chemical part of a substance; there are about 115 known elements. A compound is a combination of elements that acts as a different substance; there are over 50 million known substances.
    1. heterogeneous
    2. homogeneous
    3. heterogeneous
  1. Choice b is a solution.
  1. Iron is a metal because it is solid, is shiny, and conducts electricity and heat well.
  1. Metals are typically shiny, conduct electricity and heat well, and are malleable and ductile; nonmetals are a variety of colors and phases, are brittle in the solid phase, and do not conduct heat or electricity well.
  1. Carbon behaves as a metal because it conducts heat and electricity well. It is a nonmetal because it is black and brittle and cannot be made into sheets or wires.

Media Attributions

Figure 1.1

  • “Ice cubes” by Darren Hester © CC BY-SA (Attribution ShareAlike)
  • “Glass of Water” by Greg Riegler © CC BY (Attribution)
  • “Tea Time” by Vélocia © CC BY-NC-ND (Attribution-NonCommercial-NoDerivs)

Figure 1.2

  • “Match” © CC BY-SA (Attribution ShareAlike)

Figure 1.3

  • “Melting Ice Cubes” by ~jar[o] © CC BY (Attribution)

Figure 1.4

  • “flour and cocoa mixture” by Jessica and Lon Binder © CC BY-NC-ND (Attribution-NonCommercial-NoDerivs)
  • “a glass of water” by bryan © CC BY-ND (Attribution-NoDerivs)

Figure 1.5

  • “Pouring liquid mercury” by Bionerd © CC BY (Attribution)
  • “Sulphur-volcano” by Heidi Soosalu © CC BY-SA (Attribution ShareAlike)

Figure 1.6

  • “Describing Matter” by David W. Ball © CC BY-NC-SA (Attribution NonCommercial ShareAlike)

Figure 1.7

  • “Soaps and Shampoos” by Takashi Ota © CC BY (Attribution)
  • “English Breakfast” © CC BY-SA (Attribution ShareAlike)
  • “Langley, Trans-Canada Highway” by James.bc © CC BY-SA (Attribution ShareAlike)

Annotate

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Chemistry as a Science
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Chemistry

Copyright © 2014

                                by Jessie A. Key

            Introductory Chemistry - 1st Canadian Edition by Jessie A. Key is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.
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