1. Notes 2—Properties of Matter Mr. Pruett Monday, August 17, 2015

2. There are four phases of matter: solid liquid gas (plasma— not discussed in this unit )

3. Properties of Matter 1. Hardness 2. Elasticity 3. Brittleness 4. Malleability 5. Density 6. Viscosity 7. Buoyancy

4. 1.Hardness—Measures a solid’s resistance to scratching 2. Elasticity—measure of a solid’s ability to be stretched and then return to its original size 3. Brittleness—Measures a material’s tendency to shatter upon impact 4. Malleability—Measures a solid’s ability to be pounded into thin sheets

5. Density–property that describes the relationship between mass and volume. (how close together the molecules are) Solids Liquids Gas Molecules close together Molecules spread out further Molecules spread far apart

6. Mass Volume Density = Density of Water = 1 gram 1milliliter

7. If an object with a density of less than 1g/mL is placed in the water, it will _______. float

8. If an object with a density of greater than 1g/mL is placed in the water, it will _____. sink

9. Buoyancy Archimedes was an ancient Greek scientist who discovered that floating objects are supported by an upward force called buoyancy.Archimedes was an ancient Greek scientist who discovered that floating objects are supported by an upward force called buoyancy. Buoyancy—measure of the upward force a fluid exerts on an object.Buoyancy—measure of the upward force a fluid exerts on an object. Buoyant force is equal to the weight of the liquid that the force displaces.Buoyant force is equal to the weight of the liquid that the force displaces.

10. Viscosity—measure of a material’s resistance to flow. Not all fluids flow quickly Viscosity

11. Some fluids move slowly. They have a high viscosity. It is very viscous. Syrup pours slowly.

12. Some fluids move quickly. They have a low viscosity. Water pours quickly. It is less viscous.

13. Element—pure substance that cannot be separated into simpler substance by physical or chemical means.

14. Compounds Pure substance composed of two or more different elements joined by chemical bonds. –Made of elements in a specific ratio that is always the same –Can only be separated by chemical means, not physically

15. Mixtures A combination of two or more pure substances that are not chemically combined. substances held together by physical forces Each item retains its properties in the mixture They can be separated physically

16. Mixtures Heterogeneous—a mixture in which every sample might have a different composition. Homogeneous—a mixture in which every sample has the same composition.

18. Can you identify the following? Review before the pictures… An element contains just one type of atom. A compound contains two or more different atoms joined together. A mixture contains two or more different substances that are only physically joined together, not chemically.

19. Element, Compound, or Mixture? Rocks

20. Element, Compound, or Mixture? Rocks

21. Heterogeneous or Homogeneous? Rocks

22. Heterogeneous or Homogeneous? Rocks

23. Element, Compound, or Mixture? Copper

24. Element, Compound, or Mixture? Copper

25. Element, Compound, or Mixture? Jelly Beans

26. Element, Compound, or Mixture? Jelly Beans

27. Heterogeneous or Homogeneous? Jelly Beans

28. Heterogeneous or Homogeneous? Jelly Beans

29. Element, Compound, or Mixture? Table Sugar

30. Element, Compound, or Mixture? Table Sugar

31. Element, Compound, or Mixture? Diamond

32. Element, Compound, or Mixture? Diamond

33. Element, Compound, or Mixture? Tea

34. Element, Compound, or Mixture? Tea

35. Heterogeneous or Homogeneous? Tea

36. Heterogeneous or Homogeneous? Tea

37. Element, Compound, or Mixture? Salt

38. Element, Compound, or Mixture? Salt

39. Element, Compound, or Mixture? Neon Gas

40. Element, Compound, or Mixture? Neon Gas

41. Element, Compound, or Mixture? Salad

42. Element, Compound, or Mixture? Salad

43. Heterogeneous or Homogeneous? Salad

44. Heterogeneous or Homogeneous? Salad

45. Element, Compound, or Mixture? Pure Water

46. Element, Compound, or Mixture? Pure Water

47. Element, Compound, or Mixture? Aluminum

48. Element, Compound, or Mixture? Aluminum

49. Element, Compound, or Mixture? Lemonade

50. Element, Compound, or Mixture? Lemonade

51. Heterogeneous or Homogeneous? Lemonade

52. Heterogeneous or Homogeneous? Lemonade

53. Element, Compound, or Mixture? Silver

54. Element, Compound, or Mixture? Silver

55. Element, Compound, or Mixture? Sand

56. Element, Compound, or Mixture? Sand

57. Heterogeneous or Homogeneous? Sand

58. Heterogeneous or Homogeneous? Sand

59. How is this possible?

60. SURFACE TENSION— measurement of cohesive energy present at an interphase. Cohesion: property of like molecules sticking together

61. What’s going on at the surface of a liquid?

62. What’s going on at the surface of a liquid? Let’s take a look!

81. Particles that make up a liquid are in constant random motion; they are randomly arranged.

82. You might expect the particles at the surface to be random as shown below. (But they aren’t. Why?)

83. Cohesion!!

84. = cohesive attraction Let’s see how cohesion influences the surface:

85. Under the surface, cohesive attractions pull on individual molecules in all directions = cohesive attractions

87. = cohesive attractions

88. At the surface, pull on the molecules is sideways and downward; there is no cohesive attractions above the molecules

89. The result of this downward attraction is that surface particles are pulled downward:

92. Surface molecules are compressed more tightly together, forming a sort of skin on the surface, with less distance between molecules than compared to the ones below.

95. This attractive force also explains the rounded shape that liquids form when dropping through the air: The molecules are all being pulled toward the center.

96. This attractive force also explains the rounded shape that liquids form when dropping through the air: The molecules are all being pulled toward the center.

97. Water has a very high surface tension. Question: What property does water have that would give it such a strong surface tension? Answer: Polarity Water is a “polar” molecule.