Chapter 12 Lesssons


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Chapter 12 Lesssons

  1. 1. Chapter 12: Changes in Matter
  2. 2. You Will Discover: <ul><li>Ways that substances can change </li></ul><ul><li>How to describe and classify chemical reactions </li></ul><ul><li>How we can use chemistry to separate substances </li></ul><ul><li>How chemical technology improves our lives </li></ul>
  3. 3. Vocabulary: <ul><li>Physical change : a change in some properties of matter without forming a different kind of matter </li></ul><ul><li>Chemical change: the changing of a substance or kind of matter into a different kind of matter with different properties </li></ul><ul><li>Combustion: the process of burning </li></ul><ul><li>Reactant: substance used in a chemical reaction </li></ul><ul><li>Product: substance made during a chemical reaction </li></ul><ul><li>Chemical equation: a formula that describes a chemical reaction </li></ul><ul><li>Polymer: a large molecule made of many smaller units connected together </li></ul><ul><li>Chemical Reaction: when one or more substances change into other substances with different chemical properties </li></ul>
  4. 4. Lesson 1: What are Chemical Changes? <ul><li>Physical Changes </li></ul><ul><li>Changes in: </li></ul><ul><li>Position </li></ul><ul><li>Shape </li></ul><ul><li>Size </li></ul><ul><li>Volume </li></ul><ul><li>Phase of matter </li></ul><ul><li>Chemical Change </li></ul><ul><li>*occurs when one substance or kind of matter changes into another completely different kind of matter with different properties </li></ul>
  5. 5. Examples of Physical Change
  6. 6. Examples of Chemical Change
  7. 7. Evidence of Chemical Change <ul><li>When a chemical change occurs, atoms rearrange themselves to form different kinds of matter. </li></ul><ul><li>Examples: </li></ul><ul><li>Antacid tablets - tiny bubbles of carbon dioxide gas </li></ul><ul><li>Burning Log - gives off heat and light </li></ul>
  8. 8. Chemical Changes and Energy Changes <ul><li>During Chemical Changes: </li></ul><ul><li>* bonds between atoms break </li></ul><ul><li>* new bonds form </li></ul><ul><li>This involves taking in or giving off energy. </li></ul><ul><li>Example: </li></ul><ul><li>Combustion - gives off heat and light </li></ul>
  9. 9. Questions to Discuss <ul><li>What is the difference between a chemical change and a physical change? </li></ul><ul><li>List three types of evidence of chemical change? </li></ul><ul><li>List three types of physical changes? </li></ul><ul><li>Look at the pictures of the copper tree on pages 376 and 377, what evidence of a chemical change do you see? </li></ul>
  10. 10. Lesson 2 - What are some kinds of chemical reactions? <ul><li>During a chemical reaction , one or more substances change into other substances with different chemical and physical properties. </li></ul><ul><li>These substances are called reactants . The reactants undergo a chemical change to produce the product . </li></ul>
  11. 11. Chemical Equations <ul><li>A chemical equation is a scientific sentence that shows what is happening during a chemical reaction. </li></ul><ul><li>The reactants are listed on the left side of the equation and the product is found on the right . </li></ul>
  12. 12. Examples of Chemical Equations <ul><li>2Mg + 0 2 = 2MgO </li></ul><ul><li>Reactants Product </li></ul><ul><li>*This chemical equation creates Magnesium Oxide . </li></ul>
  13. 13. Law of Conservation of Mass <ul><li>Matter cannot be created or destroyed during a chemical reaction. </li></ul><ul><li>The total mass of the reactants is equal to the total mass of the product. </li></ul><ul><ul><ul><li>Example: If you bake a cake, the mass of the ingredients equals the mass of the cake, plus the gases that come from the oven to make the cake smell good. </li></ul></ul></ul>
  14. 14. Types of Chemical Reactions <ul><li>Decomposition reaction - compounds split apart to form smaller compounds or elements </li></ul><ul><li>Combination reaction - elements or compounds come together to form new compounds. </li></ul><ul><li>Replacement reaction - at least one molecule splits apart and the parts of that molecule switch places. </li></ul>
  15. 15. Example of Decomposition Reaction <ul><li>Electrolysis of Water </li></ul><ul><li>The water separates into Oxygen and Hydrogen atoms. This compound separates into the two different molecules . </li></ul>
  16. 16. Example of Combination Reaction <ul><li>Two separate substances are put together and they create a completely different substance with different properties </li></ul>
  17. 17. Example of Replacement Reaction <ul><li>In this reaction, the two compounds switch partners to form two new compounds. </li></ul>
  18. 18. Questions to Discuss <ul><li>What do chemical equations show? </li></ul><ul><li>List and describe the three kinds of chemical reactions. </li></ul><ul><li>When magnesium reacts with oxygen gas a reactions occurs. What type of reaction it it? Why? </li></ul><ul><li>Using the chemical equation on page 379. If you start with 100 atoms of magnesium, how many molecules of oxygen are needed to react with all the magnesium? </li></ul>
  19. 19. Lesson 3 - How are chemical properties used? <ul><li>Chemical Properties can be used: </li></ul><ul><ul><ul><li>Separating mixtures </li></ul></ul></ul><ul><ul><ul><li>Separating metals from ores </li></ul></ul></ul><ul><ul><ul><li>Identifying substances </li></ul></ul></ul>
  20. 20. Separating Mixtures <ul><li>Substances may also have different chemical properties that can be used to separate them from one another. </li></ul><ul><li>Example: </li></ul><ul><ul><ul><li>Archaeologists use vinegar to separate fossils from limestone. The vinegar dissolves the limestone, freeing the fossil. </li></ul></ul></ul>
  21. 21. Separating Metals from Ores <ul><li>Ores are rocks with metals combined with other substances. </li></ul><ul><li>Example: </li></ul><ul><ul><ul><li>Iron ore contains iron oxide. Heating iron ore in a furnace with with solid carbon allows the iron to separate from the oxygen in the ore. The result is pure iron and carbon dioxide. </li></ul></ul></ul>Iron ore
  22. 22. Identifying Substances <ul><li>Scientists use chemical properties to identify substances. </li></ul><ul><li>Acids and bases are two common types of substances. </li></ul>Acid Base
  23. 23. Acids and Bases <ul><li>Acids and Bases react with chemicals in special paper called universal indicator paper . </li></ul><ul><ul><ul><li>Acids turn the paper red </li></ul></ul></ul><ul><ul><ul><li>Bases turn the paper purple </li></ul></ul></ul><ul><li>Universal indicator paper is not enough to completely identify a substance, but helps narrow substances down. </li></ul>
  24. 24. Flame Test <ul><li>Scientists use flame tests to identify a substance. </li></ul><ul><li>A material is heated in a flame, different substances will cause the flame to have different colors . </li></ul>
  25. 25. Questions to Discuss <ul><li>How can chemical properties be used to separate substances in a mixture or compound? </li></ul><ul><li>What type of reaction is it when purifying iron ore? (2FeO + C = 2Fe + CO 2 ) </li></ul><ul><li>How might a scientist distinguish the following compounds strontium chloride and potassium chloride? </li></ul><ul><li>What color do you think indicator paper would turn if it were dipped in shampoo? Why? </li></ul>
  26. 26. Lesson 4 - How is chemical technology used in our lives? <ul><li>Chemistry and Health </li></ul><ul><li>Chemistry and New Materials </li></ul><ul><li>Chemistry and Transportation </li></ul><ul><li>Chemistry and Technology </li></ul><ul><li>Chemicals and Safety </li></ul>
  27. 27. Chemistry and Health <ul><li>Alexander Fleming made an accidental discovery that led to the development of antibiotics. </li></ul><ul><ul><ul><li>Fleming grew bacteria in dishes. One of his dishes became contaminated with mold. The mold killed the bacteria. Fleming named this mold penicillin. </li></ul></ul></ul><ul><li>Chemists have also identified substances </li></ul><ul><li>that help people stay healthy. These </li></ul><ul><li>substances are called vitamins. </li></ul>
  28. 28. Chemistry and New Materials <ul><li>Some materials are found in nature, like wool or cotton. </li></ul><ul><li>Scientists have invented some common materials, like nylon , plastic , and concrete . </li></ul><ul><ul><ul><li>Nylon is a polymer , made of six carbon atom, seven hydrogen atoms, and one nitrogen atom. </li></ul></ul></ul><ul><ul><ul><li>A polymer may have thousands or millions of units in a single chain. </li></ul></ul></ul>Plastic Nylon Concrete
  29. 29. Chemistry and Transportation <ul><li>Natural rubber comes from trees . It bends easily and is waterproof . </li></ul><ul><ul><ul><li>It becomes brittle and </li></ul></ul></ul><ul><ul><ul><li>cracks in cold weather. </li></ul></ul></ul><ul><li>Scientists discovered that by </li></ul><ul><li>heating the rubber and adding </li></ul><ul><li>sulfur they made rubber durable and usable </li></ul><ul><li>year-round . </li></ul><ul><ul><ul><li>In the 1900s scientists developed a way to make artificial rubber. </li></ul></ul></ul><ul><ul><ul><li>It is used for tires, tennis shoes </li></ul></ul></ul>
  30. 30. Chemistry and Technology
  31. 31. Chemicals and Safety <ul><li>Some chemicals are used to helps us clean and sanitize to keep use healthy. </li></ul><ul><li>When using chemicals it is important to: </li></ul><ul><ul><ul><li>Read the warning labels </li></ul></ul></ul><ul><ul><ul><li>Read the directions for use </li></ul></ul></ul><ul><ul><ul><li>Wear gloves and safety goggles </li></ul></ul></ul><ul><ul><ul><li>Open a window if necessary </li></ul></ul></ul><ul><ul><ul><li>Don’t mix any cleaners </li></ul></ul></ul>
  32. 32. Questions to Discuss <ul><li>What are the antibiotics and how have they improved health? </li></ul><ul><li>What are three common materials that were developed by scientists? </li></ul><ul><li>How did scientists working with rubber help our modern system? </li></ul><ul><li>Why is it important to avoid mixing cleaners? </li></ul><ul><li>What is a polymer? </li></ul><ul><li>Which of the technological advances has most improved human lives? </li></ul>