2. 2.1 Classifying Matter Objectives – 9/18/2015 Law of Conservation of Mass Classify pure substances as elements or compounds. Describe the characteristics of an element and the symbols used to identify elements. Describe the characteristics of a compound. Distinguish pure substances from mixtures. Classify mixtures as heterogeneous or homogeneous. Classify mixtures as solutions, suspensions, or colloids.

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4. Law of Conservation of Mass Mass is never destroyed –a relation stating that in a chemical reaction, the mass of the products equals the mass of the reactants. When we burn something it isn’t destroyed, it just changes into other compounds

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6. Matter Classification of Matter

7. 2.1 Classifying Matter A pure substance is matter that always has exactly the same composition. Table salt and table sugar are two examples of pure substances. Substances can be classified into two categories—elements and compounds. Pure Substances Every sample of a given substance has the same properties because a substance has a fixed, uniform composition.

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9. Examples of Elements Some elements are solids at room temperature. Most soft drink cans are made from aluminum. Carbon is the main element in the marks you make with a pencil. The elements oxygen and nitrogen are the main gases in the air you breathe. Two elements are liquids at room temperature–bromine and mercury. Elements

10. 2.1 Classifying Matter Symbols for Elements Chemists use symbols of one or two letters to represent elements. The first letter is always capitalized. If there is a second letter, it is not capitalized. C represents carbon. Al represents aluminum. Au represents gold. (The Latin name for gold is aurum.) Elements

11. 2.1 Classifying Matter Symbols for Elements Symbols allow scientists who speak different languages to communicate without confusion. For example, nitrogen is azote in France, stickstoff in Germany, and nitrógeno in Mexico. But all scientists use N as the symbol for the element nitrogen. Elements

12. 2.1 Classifying Matter Aluminum, carbon, and gold are elements that you can see in common objects, such as cans, pencils, and rings. Mixtures containing iodine are used to prevent and treat infections. Elements AluminumCarbonGoldIodine

13. 2.1 Classifying Matter A compound always contains two or more elements joined in a fixed proportion. Compounds A compound is a substance that is made from two or more simpler substances and can be broken down into those simpler substances.

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15. The properties of a compound differ from those of the substances from which it is made. Water is composed of the elements hydrogen and oxygen. Oxygen and hydrogen are gases at room temperature, but water is a liquid. Hydrogen can fuel a fire, and oxygen can keep a fire burning, but water does not burn or help other substances to burn. Compounds

16. 2.1 Classifying Matter Silicon dioxide is a compound found in most light- colored grains of sand and in crystals of quartz. It is a colorless, transparent solid. Yet, silicon dioxide is made from a colorless gas (oxygen) and a gray solid (silicon). In silicon dioxide, there are always two oxygen atoms for each silicon atom. Compounds Silicon Oxygen Silicon dioxide

17. 2.1 Classifying Matter Identify the following as an element or a compound Sucrose (table sugar) The helium in a balloon Baking soda A diamond Aluminum foil Calcium Chloride pellets used to melt ice. Compound Element Compound Element Compound

18. 2.1 Classifying Matter If you make salsa, a recipe can guide you. You can use exactly the amounts in the recipe, or you can adjust the ingredients to your own taste. Salsa is a mixture. Each batch may be slightly different. Mixtures

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20. Mixtures can be classified by how well the parts of the mixture are distributed throughout the mixture. Heterogeneous Mixtures In a heterogeneous mixture, the parts of the mixture are noticeably different from one another. Homogeneous Mixtures In a homogeneous mixture, the substances are so evenly distributed that it is difficult to distinguish one substance in the mixture from another. Mixtures

21. 2.1 Classifying Matter The sand is a heterogeneous mixture of different kinds of grains. The spoon is stainless steel, a homogeneous mixture of iron, chromium, and nickel. Mixtures

22. 2.1 Classifying Matter Solutions When substances dissolve and form a homogeneous mixture, the mixture that forms is called a solution. Suspensions A suspension is a heterogeneous mixture that separates into layers over time. Solutions, Suspensions, and Colloids

23. 2.1 Classifying Matter Colloids A colloid contains some particles that are intermediate in size between the small particles in a solution and the larger particles in a suspension. Like solutions, colloids do not separate into layers. You cannot use a filter to separate the parts of a colloid. Solutions, Suspensions, and Colloids

24. 2.1 Classifying Matter These liquids represent three categories of mixtures. Windshield wiper fluid is a solution. Muddy water collected from a swamp is a suspension. Milk is a colloid. Solutions, Suspensions, and Colloids

25. 2.1 Classifying Matter homogeneous or heterogeneous mixture 70% isopropyl alcohol A pile of rusty iron filings Concrete Saltwater Gasoline Bread Homogeneous Heterogeneous Homogeneous Heterogeneous

26. 2.1 Classifying Matter Do the Contents of Two Cans of Mixed Nuts Meet FDA Regulations? According to Food and Drug Administration (FDA) regulations, a can labeled mixed nuts must contain at least four types of shelled nuts other than peanuts. The mass of each type of nut must be not less than 2 percent of the total mass and not more than 80 percent of the total mass. Mixtures

27. 2.1 Classifying Matter 1. Comparing and Contrasting How are the two brands of mixed nuts alike? How are they different? Answer: Mixtures

28. 2.1 Classifying Matter 1. Comparing and Contrasting How are the two brands of mixed nuts alike? How are they different? Answer: Both brands contain the same types of nuts but the amount of each type differs. Mixtures

29. 2.1 Classifying Matter 2. Calculating What is the percent by mass of each type of nut in each can? Answer: Mixtures

30. 2.1 Classifying Matter 2. Calculating What is the percent by mass of each type of nut in each can? Answer: Brand A: 44.2% peanuts, 13.64% almonds, 16.79% Brazil nuts, 13.4% cashews, 5.77% hazelnuts, and 6.21% pecans Brand B: 54.8% peanuts, 8.90% almonds, 5.59% Brazil nuts, 21.06% cashews, 4.82% hazelnuts, and 4.82% pecans Mixtures

31. 2.1 Classifying Matter 3. Drawing Conclusions Do the contents of each can meet the FDA regulations? Explain. Answer: Mixtures

32. 2.1 Classifying Matter 3. Drawing Conclusions Do the contents of each can meet the FDA regulations? Explain. Answer: Yes. Both brands contain more than four types of nuts other than peanuts. The masses are within the 2% to 80% range. Mixtures

33. 2.1 Classifying Matter 4. Inferring On the Brand A label, the nuts are listed in this order: peanuts, Brazil nuts, almonds, cashews, pecans, and hazelnuts. What do you think determines the order? Answer: Mixtures

34. 2.1 Classifying Matter 4. Inferring On the Brand A label, the nuts are listed in this order: peanuts, Brazil nuts, almonds, cashews, pecans, and hazelnuts. What do you think determines the order? Answer: The ingredients are listed in order by total mass. The ingredient with the largest mass is listed first. Mixtures

35. 2.1 Classifying Matter Assessment Questions 1.Which of these substances is a compound? a.copper b.water c.oxygen d.carbon

36. 2.1 Classifying Matter Assessment Questions 1.Which of these substances is a compound? a.copper b.water c.oxygen d.carbon ANS:B

37. 2.1 Classifying Matter Assessment Questions 2.Which of these groups of letters could be used as a symbol for an element? a.HF b.Cm c.Car d.fe

38. 2.1 Classifying Matter Assessment Questions 2.Which of these groups of letters could be used as a symbol for an element? a.HF b.Cm c.Car d.fe ANS:B

39. 2.1 Classifying Matter Assessment Questions 3.Which of the following statements does not apply to a compound? a.It is made of two or more elements. b.It has components that are joined in fixed proportions. c.It can be separated into components by physical methods. d.It can be broken down into elements or other compounds.

40. 2.1 Classifying Matter Assessment Questions 3.Which of the following statements does not apply to a compound? a.It is made of two or more elements. b.It has components that are joined in fixed proportions. c.It can be separated into components by physical methods. d.It can be broken down into elements or other compounds. ANS:C

41. 2.1 Classifying Matter Assessment Questions 4.How does a compound differ from a mixture? a.A compound cannot be broken down into simpler substances. b.Compounds can be separated by physical processes and mixtures cannot. c.The composition of a mixture cannot vary. d.A compound is made of two or more elements in fixed proportion.

42. 2.1 Classifying Matter Assessment Questions 4.How does a compound differ from a mixture? a.A compound cannot be broken down into simpler substances. b.Compounds can be separated by physical processes and mixtures cannot. c.The composition of a mixture cannot vary. d.A compound is made of two or more elements in fixed proportion. ANS:D

43. 2.1 Classifying Matter Assessment Questions 5.Which of these materials is a heterogeneous mixture? a.air b.seawater c.sand d.steel

44. 2.1 Classifying Matter Assessment Questions 5.Which of these materials is a heterogeneous mixture? a.air b.seawater c.sand d.steel ANS:C

45. 2.1 Classifying Matter Assessment Questions 6.Which of the following can be separated with a filter? a.colloids b.compounds c.solutions d.suspensions

46. 2.1 Classifying Matter Assessment Questions 6.Which of the following can be separated with a filter? a.colloids b.compounds c.solutions d.suspensions ANS:D