What’s the MATTER: Classify Changes of Matter

1. What’s the MATTER:Classify Changes of Matter Chemical vs. Physical Changes

2. Matter, Classify Changes of Matter At the conclusion of our time together, you should be able to: Characterize various changes of matter Recognize that a change of state in matter is a physical change

3. Interesting Signs:

4. Physical Change Physical • A change in matter from one form to another without changing its chemical properties • the substances are not altered chemically, but are merely changed to another phase (i.e. gas, liquid, solid) or separated or combined. • (most can be reversed) • No change in identity of the matter.

5. Physical Change • Examples = • Change in state or phase change • Dissolving • Compressing • Light emission/absorption • Electrons passing through metals

6. Physical Change More Examples = • boiling of a liquid • melting of a solid • dissolving a solid in a liquid to give a homogeneous mixture • making a solution

7. Chemical Change • the substances are altered chemically and display different physical and chemical properties after the change. • Atoms in the reactants are rearranged to form one or more differentsubstances • Old bonds are broken; new bonds form

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9. 2 1 Chemical Change Chemical • Bonds are made / broken • Change in oxidation states Li +1 Cl-1 Cl-1

10. 2 1 Chemical Change Chemical • In this case, Li loses one electron to the Cl. It will split the chlorine molecule and form LiCl, lithium chloride. Li +1 Cl-1

11. Possible Signs of a Chemical Change“Chemists Get Practice Trying Labs” • Color Change • Gas Produced ( not from boiling!) • Precipitate – a solid formed by mixing two liquids together • Temperature Change Exothermic (hot) or endothermic (cold) • Light Typically, more than one indicator will be seen.

12. Learning Check Classify each of the following as a 1) physical change or 2) chemical change A. ____ a burning candle B. ____ melting ice C. ____ toasting a marshmallow D. ____ cutting a pizza E. ____ Tarnished silver 2 1 2 1 2

13. Chemical Reaction A process in which at least one new substance is produced as a result of chemical change.

14. In a chemical reaction • The way atoms are joined is changed • Atoms aren’t created or destroyed. • Can be described several ways: • In a sentence • Copper reacts with chlorine to form copper (II) chloride. • In a word equation • Copper + chlorine ® copper (II) chloride • Formulas • Cu+ Cl2 CuCl2

15. Examples of Chemical Change • Chemical change or chemical reaction — transformation of one or more atoms or molecules into one or more different molecules. • Burning hydrogen (H2) in oxygen (O2) gives H2O.

16. Will This be on the Test????

17. A Chemical Equation Reactants Products

18. Remember the Law of Conservation of Mass • In a physical change or a chemical reaction, mass (and energy) is neither created or destroyed, but can change form. (Antoine Lavoisier)

19. Conservation of Mass and Energy • Mass and Energy cannot be created or destroyed, but can change form

20. Symbols Used In Equations •  separates the reactants from products • Read as “reacts to form” or “yields” • + read as “and” or “reacts with” • (s) after the formula -solid • (g) after the formula -gas • (l) after the formula –liquid • (aq) after the formula- aqueous solution • Dissolved in water.

21. More Symbols used in Equations • ­ used after a product indicates a gas; same as (g) • ¯used after a product indicates a solid or ppt (precipitate); same as (s)

22. Even More Symbols used in Equations • indicates a reversible reaction (More later) • shows that heat is supplied to the reaction • is used to indicate a catalyst was supplied, in this case, platinum.

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24. What Is A Catalyst? • A substance that speeds up a reaction without being changed by the reaction. • Enzymes are biological or protein catalysts.

25. Diatomic Elements • There are 8 elements that never want to be alone. • If they are not with another element, they form diatomic molecules. • H2 , N2 , O2 , F2 , Cl2 , Br2 , I2 , and At2 • @ Brother HON CLIF • 1 + 7 pattern on the periodic table

26. 1 + 7 Pattern On The Periodic Table

27. Matter, Classify Changes of Matter Let’s see if you can: Characterize various changes of matter Recognize that a change of state in matter is a physical change

28. Physical vs. Chemical Change • physical • chemical • physical • physical • chemical • Examples: • melting • flame produced • paper cut • dissolving salt in water • tarnishes in air

29. Physical vs. Chemical Change • chemical • physical • chemical • physical • physical • Examples: • rusting iron • mixing mud and water • burning a log • freezing water • grinding spices

30. A difference between physical change and chemical change is that • chemical change involves energy while physical change does not. • physical change involves energy while chemical change does not. • different kinds of molecules are present after a physical change but not after a chemical change. • different kinds of molecules are present after a chemical change but not after a physical change

31. In making a pizza, which process involves a chemical change? Mixing spices for the sauce Slicing pepperoni for the topping Spreading cheese on the pizza Baking the dough to form the crust

32. All You Really Need To Know You Can Learn From Noah's Ark • Remember that the ark was built by amateurs; the Titanic was built by professionals. • Remember that woodpeckers inside are a larger threat than the storm outside.