2. The Principles of Matter

3. Matter Everything is made of matter.

4. Matter Has mass. Takes up space.

5. Matter Is made of atoms.

6. The Atom

7. Atom The atom has three parts…

8. Proton Has positive charge. ~1/2 of atom’s mass.

9. Atom Neutron No charge (neutral). ~1/2 of atom’s mass.

10. Atom Electron Negative Charge (-). Has almost no mass.

11. Atom It is very small! It is mostly empty space!

12. Atom If a proton were the size of a basketball…

13. Atom the electron would be ten miles away.

14. How did we learn about the atom?

15. Everything is made of matter.

16. We have known about the atom over the last 2500 years.

17. Here are those scientists who have contributed to our knowledge of the atom.

18. Introducing the members of the Atom Hall of Fame!

19. Democritus

20. He was the first person to propose the existence of the atom.

21. 400 B.C. Democritus proposed the following thought experiment.

22. Take a pie. Slice the pie in half.

23. Take one of the halves and slice that in half.

24. Continue slicing the pie into smaller and smaller pieces.

25. Eventually you will not be able to slice your pie any smaller.

26. He called that piece “atomos.” (“Atomos” means cannot be divided.)

27. Democritus

28. John Dalton

29. 1803 – Dalton proposed that matter is composed of atoms.

30. He came up with the following laws: Matter: 1. Is made of atoms. 2. Atoms cannot be divided into smaller pieces.

31. Matter: 3. Atoms of an element are exactly alike. 4. Different elements are made up of different atoms.

32. Matter: 5. Compounds are made of two or more joined atoms.

33. Dalton’s model of the atom was that of a solid, uniform sphere.

34. John Dalton

35. Sir J. Joseph Thomson

36. 1897 – Discovered the electron. He developed the “plum pudding” model.

37. He believed the atom was a solid, uniform mass with electrons inside the atom.

39. Sir J. Joseph Thomson

40. Lord Ernest Rutherford

41. 1910 – an atom must be mostly empty space with a small dense positively charged particle in the center surrounded by negatively charged electrons.

42. First person to observe protons.

43. Lord Ernest Rutherford

44. Neils Bohr

45. 1913 – Electrons orbit the nucleus of the atom. Developed quantum mechanics.

46. Neils Bohr

47. Sir James Chadwick

48. 1926 – Discovered the neutron.

49. Sir James Chadwick

50. Werner Heisenberg

51. 1932 – Developed the Uncertainty Principle. It is impossible to know both the speed and location of an electron.

52. You can only know either its speed or its location.

53. Werner Heisenberg

54. These are the members of the Atom Hall of Fame.

55. Modeling the Atom.

56. The Three Phases (States) of Matter

57. Matter Properties of Matter.

58. Matter comes in three phases (or states).

59. Solid

60. Has a definite shape. Has definite volume. Does not change shape when moved.

61. The particles in a solid are tightly packed and vibrate in place.

63. Liquid

64. Has definite volume. Has no definite shape (it takes the shape of its container.)

65. The molecules are more loosely packed. They do not stay in one place.

66. They move over and around each other.

68. Gas

69. Invisible Has no definite shape. Has no definite volume.

70. The molecules are very far apart. Spread out evenly to fill space they enter

71. This process is called diffusion.

72. The particles in a gas move rapidly.

74. Changes in phases (states) of matter.

75. Melting A solid changing to a liquid.

76. Melting The particles start moving faster.

77. Freezing Going from a liquid to a solid.

78. Freezing The particles slow down.

80. Sublimation Changing from a solid to a gas.

81. Example Dry Ice

82. Boiling Changing from a liquid to a gas.

83. Boiling Energy is added and the particles move faster.

84. Evaporation Changing from a liquid to a gas.

85. Evaporation No energy is added.

86. Evaporation Happens on the surface.

87. Condensation Changing from a gas to a liquid.

88. The particles slow down.