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1. How to Use This Presentation • To View the presentation as a slideshow with effects select “View” on the menu bar and click on “Slide Show.” • To advance through the presentation, click the right-arrow key or the space bar. • From the resources slide, click on any resource to see a presentation for that resource. • From the Chapter menu screen click on any lesson to go directly to that lesson’s presentation. • You may exit the slide show at any time by pressing the Esc key.

2. Resources Bellringers Chapter Presentation Transparencies Standardized Test Prep Image and Math Focus Bank CNN Videos Visual Concepts

3. Chemical Reactions Chapter 14 Table of Contents Section 1 Forming New Substances Section 2 Chemical Formulas and Equations Section 3 Types of Chemical Reactions Section 4 Energy and Rates of Chemical Reactions

4. Chapter 14 Section 1 Forming New Substances Bellringer What do baking bread, launching the space shuttle, and digesting food have in common? Write your answer in yourscience journal.

5. Chapter 14 Section 1 Forming New Substances Objectives • Describe how chemical reactions produce new substances that have different chemical and physical properties. • Identify four signs that indicate that a chemical reaction might be taking place. • Explain what happens to chemical bonds during a chemical reaction.

6. Chapter 14 Section 1 Forming New Substances Chemical Reactions • Achemical reactionis a process in which one or more substances change to make one or more new substances. • The chemical and physical properties of the new substances differ from those of the original substances.

7. Chapter 14 Section 1 Forming New Substances Chemical Reactions, continued • Signs of Chemical Reactions include color changes, gas formation, the formation of aprecipitate(a solid substance formed in a solution), and energy given off as light, thermal energy, or electrical energy. • A Change of PropertiesThe most important sign of a chemical reaction is the formation of new substances that have different properties.

8. Chapter 14 Section 1 Forming New Substances Bonds: Holding Molecules Together • A chemical bond is an attraction that holds atoms together in a molecule. • Breaking and Making BondsIf molecules bump into each other with enough energy, the chemical bonds in the molecules break. The atoms then rearrange, and new bonds form to make new substances.

9. Chapter 14 Section 1 Forming New Substances

10. Chapter 14 Section 1 Forming New Substances Bonds: Holding Molecules Together, continued • New Bonds, New SubstancesWhenever new substances form, their properties differ from the properties of the starting substances. • For example, sodium is a violently reactive metal and chlorine is a greenish poisonous gas. The two elements combine to form a white solid called sodium chloride, or table salt.

11. Chapter 14 Section 2 Chemical Formulas and Equations Bellringer Write the following chemical symbols in yourscience journal. Then, try to write the names of the elements matching the symbols. H O C Na N Cl K Mg Ca Al Au F Cu Fe

12. Chapter 14 Section 2 Chemical Formulas and Equations Objectives • Interpret and write simple chemical formulas. • Write and balance simple chemical equations. • Explain how a balanced equation shows the law of conservation of mass.

13. Chapter 14 Section 2 Chemical Formulas and Equations Chemical Formulas • Achemical formulais a combination of chemical symbols and numbers to represent a substance. A chemical formula shows how many atoms of each kind are present in a molecule.

14. Chapter 14 Section 2 Chemical Formulas and Equations Chemical Formula Click below to watch the Visual Concept. You may stop the video at any time by pressing the Esc key. Visual Concept

15. Chapter 14 Section 2 Chemical Formulas and Equations Chemical Formulas, continued • Writing Formulas for Covalent Compounds You can use the name of a covalent compound to write its chemical formula. The names of covalent compounds use prefixes. Each prefix represents a number, as shown below.

16. Chapter 14 Section 2 Chemical Formulas and Equations Chemical Formulas, continued • Writing Formulas for Ionic CompoundsTo write the formula for an ionic compound, make sure the compound’s charge is 0. • The formula must have subscripts that cause the charges of the ions to cancel out.

17. Chapter 14 Section 2 Chemical Formulas and Equations

18. Chapter 14 Section 2 Chemical Formulas and Equations Chemical Equations • Describing Reactions by Using EquationsAchemical equationuses chemical symbols and formulas as a shortcut to describe a chemical reaction. • From Reactants to ProductsThe starting materials in a reaction arereactants.The substances formed from a reaction areproducts.

19. Chapter 14 Section 2 Chemical Formulas and Equations

20. Chapter 14 Section 2 Chemical Formulas and Equations Chemical Equations, continued • The Importance of AccuracyThe symbol or formula for each substance in a chemical equation must be written correctly or it will not correctly describe the reaction. Some formulas and symbols can be confused.

21. Chapter 14 Section 2 Chemical Formulas and Equations Chemical Equations, continued • The Reason Equations Must Be BalancedAtoms are never lost or gained in a chemical reaction, they are just rearranged. Every atom in the reactants becomes part of the products. • When writing a chemical equation, make sure the number of atoms of each element in the reactants equals the number of atoms of those same elements in the products. This is called balancing the equation.

22. Chapter 14 Section 2 Chemical Formulas and Equations Chemical Equations, continued • In the 1700s, French chemist Antoine Lavoisier found that the total mass of the reactants was always the same as the total mass of the products. • Lavoisier’s work led to the law of conservation of mass,which states that mass is neither created nor destroyed in ordinary chemical and physical changes.

23. Chapter 14 Section 2 Chemical Formulas and Equations Chemical Equations, continued • How to Balance an EquationTo balance an equation, you must use coefficients. A coefficient is a number that is placed in front of a chemical symbol or formula. • For an equation to be balanced, all atoms must be counted. So, you multiply the subscript of each element in a formula by the formula’s coefficient. • The next slide shows how to use coefficients to balance an equation.

24. Chapter 14 Section 2 Chemical Formulas and Equations

25. Chapter 14 Section 3 Types of Chemical Reactions Bellringer Are the products of a reaction always more complex than the reactants? Could products be simpler than the reactants? Explain your answers. Write your responses in yourscience journal.

26. Chapter 14 Section 3 Types of Chemical Reactions Objectives • Describe four types of chemical reactions. • Classify a chemical equation as one of four types of chemical reactions.

27. Chapter 14 Section 3 Types of Chemical Reactions Synthesis Reactions • Asynthesis reactionis a reaction in which two or more substances combine to form one new compound. • For example, a synthesis reaction takes place when sodium reacts with chlorine to produce sodium chloride, which you know as table salt.

28. Chapter 14 Section 3 Types of Chemical Reactions Decomposition Reactions • Adecomposition reactionis a reaction in which a single compound breaks down to form two or more simpler substances. • Decomposition is the reverse of synthesis.

29. Chapter 14 Section 3 Types of Chemical Reactions Single-Displacement Reactions • Asingle-displacement reactionis a reaction in which an element replaces another element that is part of a compound. The products of single-displacement reactions are a new compound and a different element. • Reactivity of ElementsIn a single-displacement reaction, a more reactive element can displace a less reactive element in a compound.

30. Chapter 14 Section 3 Types of Chemical Reactions Double-Displacement Reactions • Adouble-displacement reactionis a reaction in which ions from two compounds exchange places. One of the products of this type of reaction is often a gas or a precipitate. • The next slide shows models of each of the four types of chemical reactions.

31. Chapter 14 Section 3 Types of Chemical Reactions

32. Chapter 14 Section 4 Energy and Rates of Chemical Reactions Bellringer Now that you know a little about chemical reactions, think about the many chemical reactions that take place around you every day. Describe your favorite chemical reaction. How do you think energy is involved in the reaction? Write your answer in yourscience journal.

33. Chapter 14 Section 4 Energy and Rates of Chemical Reactions Objectives • Compare exothermic and endothermic reactions. • Explain activation energy. • Interpret an energy diagram. • Describe five factors that affect the rate of a reaction.

34. Chapter 14 Section 4 Energy and Rates of Chemical Reactions Reactions and Energy • By comparing the chemical energy of the reactants with the chemical energy of the products, you can decide if energy is released or absorbed in the reaction. • Exothermic Reactionsare reactions in which energy is released. Energy can be released as light, electrical energy, or thermal energy.

35. Chapter 14 Section 4 Energy and Rates of Chemical Reactions Reactions and Energy, continued • Endothermic Reactionsare reactions in which energy is taken in. • The Law of Conservation of Energystates that energy cannot be created or destroyed. The energy released in exothermic reactions was first stored in the chemical bonds of the reactants. And the energy taken in during endothermic reactions is stored in the products.

36. Chapter 14 Section 4 Energy and Rates of Chemical Reactions Rates of Reactions • The speed at which new particles form is called the rate of a reaction. • Activation Energyis the smallest amount of energy that molecules need to react. A chemical reaction needs a boost of energy greater than or equal to the activation energy before the reaction can start.

37. Chapter 14 Section 4 Energy and Rates of Chemical Reactions Rates of Reactions, continued • Sources of Activation EnergyFriction is one source of activation energy. In a match, friction provides the energy needed to break the bonds in the reactants and allow new bonds to form. • An electric spark in a car’s engine is another source of activation energy. This spark begins the burning of gasoline. • Light can also be a source of activation energy for a reaction.

38. Chapter 14 Section 4 Energy and Rates of Chemical Reactions Activation Energy and Chemical Reactions Click below to watch the Visual Concept. You may stop the video at any time by pressing the Esc key. Visual Concept

39. Chapter 14 Section 4 Energy and Rates of Chemical Reactions Factors Affecting Rates of Reactions • TemperatureA higher temperature causes a faster rate of reaction. At high temperatures, particles of reactants move quickly and collide hard and often. • At low temperatures, particles move slowly and collide less often.

40. Chapter 14 Section 4 Energy and Rates of Chemical Reactions Factors Affecting Rates of Reactions, continued • Concentration In general, a high concentration of reactants causes a fast rate of reaction. Concentration is a measure of the amount of one substance when it is dissolved in another substance. • When concentration is high, there are many reactant particles in a given volume. So, there is little distance between particles and the particles collide more often and react faster.

41. Chapter 14 Section 4 Energy and Rates of Chemical Reactions Factors Affecting Rates of Reactions, continued • Surface Area is the amount of exposed surface of a substance. Increasing the surface area of solid reactants increases the rate of a reaction. • Inhibitorsare substances that slow down or stop a chemical reaction. The rate of a reaction decreases in the presence of an inhibitor.

42. Chapter 14 Section 4 Energy and Rates of Chemical Reactions Factors Affecting Rates of Reactions, continued • Catalysts are substances that speed up a reaction without being permanently changed. Because it is not changed, a catalyst is not a reactant. • A catalyst lowers the activation energy of a reaction, which allows the reaction to happen more quickly. • Catalysts called enzymes speed up most reactions in your body.

43. Chapter 14 Chemical Reactions Concept Map Use the terms below to complete the concept map on the next slide.

44. Chapter 14 Chemical Reactions

45. Chapter 14 Chemical Reactions

46. End of Chapter 14 Show

47. Standardized Test Preparation Chapter 14 Reading Read each of the passages. Then answer the questions that follow each passage.

48. Standardized Test Preparation Chapter 14 Passage 1The key to an air bag’s success during a crash is the speed at which it inflates. Inside the bag is a gas generator that contains the compounds sodium azide, potassium nitrate, and silicon dioxide. At the moment of a crash, an electronic sensor in the car detects the sudden change in speed. The sensor sends a small electric current to the gas generator. Continued on the next slide

49. Standardized Test Preparation Chapter 14 Passage 1, continuedThis electric current provides the activation energy for the chemicals in the gas generator. The rate at which the reaction happens is very fast. In 1/25 of a second, the gas formed in the reaction inflates the bag. The air bag fills upward and outward. By filling the space between a person and the car’s dashboard, the air bag protects him or her from getting hurt.

50. Standardized Test Preparation Chapter 14 1. Which of the following events happens first? A The sensor sends an electric current to the gas generator. BThe air bag inflates. C The air bag fills the space between the person and the dashboard. DThe sensor detects a change in speed.