Unit 2- Materials: Structure and Uses

1. Unit 2- Materials: Structure and Uses

2. Unit 2- Materials: Structure and Uses Section 2. A – Why we use what we do

3. Do Now • Read pages. 108-109

4. Objectives • 1. Define properties and changes. • 2. Distinguish between physical and chemical changes and classify examples of each. • 3. Differentiate between metals, non metals, and metalloids and their locations on the period table. • 4. Distinguish between isotopes based on total neutrons.

5. Unit 2. A.1-A3: Reading Guide • Complete the reading guide worksheet • Due:

6. 2.A.1: Properties make the difference • What are some materials people of the past have used as currency? • What makes a material suitable or useable to produce coins? • How important is appearance or cost? • Answers depend on physical and chemical properties

7. Physical Properties • Characteristics that distinguish elements from other things • Ex. Color, density, odor… • Can be observed without altering chemical structure

8. Physical Properties • Physical properties and the ability of a material to undergo physical changes, such as melting, boiling and bending, influence the use of that material. • In a physical change, the material remains the same, although it form appears to have changed.

9. Chemical Property • Describes how the element reacts with other elements or substances. • When a substance changes into one or more new substances, it has undergone a chemical change. • A substance’s chemical properties, often determine the substance’s usefulness.

10. Chemical Property • Chemical change is often observed such as: formation of a gas or solid, a permanent color change or a temperature change.

11. Physical vs. Chemical Property Copper metal Physical Chemical

12. Chemical vs. Physical Changes

13. Example • Iron RUSTING: • Observing a chemical change can often mean the formation of a gas or solid • Thermal energy can be given off or absorbed • Permanent color change • Temperature change

14. 2.A.2: Physical and Chemical Properties

15. Objectives • Distinguish between physical and chemical changes and classify examples of each.

16. Problem 1: p.111 • Consider the statement: Copper compounds are often blue in color. Does this statement describe a physical or chemical property? Why?

17. Answer • Consider the statement: Copper compounds are often blue in color. Does this statement describe a physical or chemical property? • Color is a characteristic physical property of many compounds

18. Problem 2: p. 111 • Consider this statement: Oxygen gas supports the burning of wood. Does this statement refer to the physical or chemical property of oxygen gas? Explain.

19. Answer • Burning or combustion of wood- involves a chemical reaction • Wood and oxygen (reactants) change into ash, carbon dioxide and water vapor.

20. Do Now • List at least one chemical property and one physical property

21. Homework • Page 112: Questions #1-9 • Due:

22. Unit 2. A1 • Quiz – complete A.1 supplement worksheet

23. A.3: Properties Matter • Considerations when selecting materials • for a specific use: • Cost • Desired properties (physical and chemical) • Available in sufficient quantities

24. A.3: Properties Matter: Designing the Penny • 1. Cost • A. Cost of the production of the penny must be matched by it’s face value ($0.01) • B. Early 1980s Copper became too expensive and Zinc replaced it in most of the penny (interior) • C. In 1943, during WWII, Zinc plated steel pennies (quickly corroded)

26. A.3: Properties Matter: Designing the Penny • 2. Solution • Post 1982 pennies – 97.5% Zinc • Copper coating a Zinc Core

27. A.4: Chemical Elements

28. Objectives • Identify properties of metals, nonmetals, or metalloids

29. A.4: Chemical Elements • Elements are classified in three major groups: • Metals • Nonmetals • Metalloids • Use the periodic table to distinguish the classes of elements

30. Periodic Trends

31. Transition Metals Transition metals

32. Physical Properties of Metals • Malleability • Ductility • Luster • Heat conductors and electrical conductors • Typically reacts with acids • Ex. Iron (Fe), tin (Sn), zinc (Zn), and copper (Cu)

33. Properties of Nonmetals • Dull in appearance • Brittle • Do not conduct electricity • Ex. Carbon (C) and Oxygen (O)

34. Metalloids • Properties of metals and nonmetals • Ex. Silicon (Si) and Germanium (Ge) • Common in the computer industry

35. Class Project A.4 Supplement handout Due:

36. Do Now • List the following as a chemical or physical change: • 1. A piece of wood burns to form ash. • 2. Water evaporates into steam. • 3. A piece of cork is cut in half. • 4. A bicycle chain rusts. • 5. Food is digested in the stomach. • 6. Water is absorbed by a paper towel. • 7. A change in color

37. A.5: Metal or Nonmetal Lab Handout

38. Periodic Trends

41. A.6: Periodic Table • 1. Review physical and chemical changes • 2. Identify trends in the periodic table. Objectives

42. Periodic Table • By the mid-1800’s, chemists has identified about 60 elements • Five were gases: hydrogen, oxygen, nitrogen, fluorine and chlorine • Two liquids: bromine and mercury • The rest were solids

43. A.6: Periodic Table • Used to organize elements based on their similar properties

44. Dimitri Mendeleev • Created a periodic table (1869) of elements based on: • 1. Atomic Weights • 2. “Combining Capacity” (how atoms react with other atoms.

45. Periodic Table • Elements with similar chemical properties were placed in the same vertical column. • Horizontal arrangements were based on increasing atomic weights of the elements.

46. Now you Try A.7: Grouping the Elements • Turn to page 119 and follow steps #1-6 • Try to create your own periodic table based on several different properties

47. A.8: The Pattern of Atomic Numbers • Creators of early periodic tables were unable to explain the similarities in properties among neighboring elements. • All elements in the leftmost column are very reactive metals. • All elements in the rightmost column are unreactive (noble) gases. • 50 years after Mendeleev for explanation.

48. A.8: • All atoms are composed of smaller particles, including equal numbers of positively charged protons and negatively charged electrons.

49. Atomic Number – the number of protons • Identifies each atom as a particular element. • Each element has its own unique atomic number. • Example: each sodium atom contains 11 protons. Atomic number of sodium is 11

50. The carbon atom contains 6 protons. Atomic number of sodium is 6 • The fluorine atom has 9 protons and an atomic number of 9 • Magnesium has 12 protons and an atomic number of 12