1. The Structure of the Atom Chap. 4

2. I. History

3. A. Early Greeks Explain matter with 4 ‘elements’

4. I. History A. Early Greeks 1. Air 2. Earth 3. Fire 4. Water Explain matter with 4 ‘elements’

5. I. History A. Early Greeks B. Democritus Greek philosopher who first introduced concept of ‘atomos’

6. I. History A. Early Greeks B. Democritus C. Alchemists Devoted to making precious metals from base metals

7. Formulated the ‘Atomic Theory of Matter’ I. History A. Early Greeks B. Democritus C. Alchemists D. Dalton

8. Atomic Theory of Matter 1. All matter is made of...

9. Atomic Theory of Matter 1. All matter is made of... 2. Atoms cannot be...

10. Atomic Theory of Matter 1. All matter is made of... 2. Atoms cannot be... 3. Atoms of a given element...

11. Atomic Theory of Matter 1. All matter is made of... 2. Atoms cannot be... 3. Atoms of a given element... 4. Atoms of 2 different elements..

12. Atomic Theory of Matter 1. All matter is made of... 2. Atoms cannot be... 3. Atoms of a given element... 4. Atoms of different elements... 5. In a chemical reaction atoms are

13. I. History A. Early Greeks B. Democritus C. Alchemists D.Dalton E.Definition of Atom

14. Atom The smallest particle of an element that retains properties of that element.

15. Used a cathode ray tube (CRT) to measure the charge:mass ratio of an electron A.J.J. Thomson – 1890s II. Discoveries of atoms

16. A.J.J. Thomson – 1890s 1.chg:mass = 1.76 x 10 11 C/kg

17. A.J.J. Thomson – 1890s 1.chg:mass = 1.76 x 10 11 C/kg 2.Discovery led to plum-pudding model II. Discoveries of atoms

18. A.J.J. Thomson – 1890s B.Robert Millikan - 1909 Measured the charge of an electron in his ‘oil drop’ exper. II. Discoveries of atoms

19. A.J.J. Thomson – 1890s B.Robert Millikan - 1909 1.Charge = 1.6 x 10 -19 II. Discoveries of atoms

20. A.J.J. Thomson – 1890s B.Robert Millikan - 1909 C.Rutherford - 1911 Discovered nucleus in gold-foil experiment II. Discoveries of atoms

21. A.J.J. Thomson – 1890s B.Robert Millikan - 1909 C.Rutherford - 1911 1.Fired alpha particles at thin metal sheet. II. Discoveries of atoms

22. A.J.J. Thomson – 1890s B.Robert Millikan - 1909 C.Rutherford - 1911 1.Fired alpha particles at thin metal sheet. 2.Expected them to go straight through, but some deflected. II. Discoveries of atoms

23. A.J.J. Thomson – 1890s B.Robert Millikan - 1909 C.Rutherford - 1911 1.Fired alpha particles at thin metal sheet. 2.Expected them to go straight through, but some deflected. 3.This led to nuclear model. II. Discoveries of atoms

24. D.The atom II. Discoveries of atoms

25. D.The atom 1.The electron was discovered first II. Discoveries of atoms

26. D.The atom 1.The electron was discovered first 2.The proton was described by Rutherford II. Discoveries of atoms

27. D.The atom 1.The electron was discovered first 2.The proton was described by Rutherford 3.The neutron was described by Chadwick II. Discoveries of atoms

28. III. Representing Atoms What makes a carbon atom different from a nitrogen atom?

29. A.The atomic number III. Representing Atoms

30. A.The atomic number 1.The number of protons III. Representing Atoms

31. A.The atomic number 1.The number of protons 2.Written on the periodic table. III. Representing Atoms

32. A.The atomic number 1.The number of protons 2.Written on the periodic table. 3.This will equal the number of electrons, too. III. Representing Atoms

33. A.The atomic number B.The mass number III. Representing Atoms

34. A.The atomic number B.The mass number 1.The number of protons + neutrons III. Representing Atoms

35. A.The atomic number B.The mass number 1.The number of protons + neutrons 2.Always a whole number III. Representing Atoms

36. A.The atomic number B.The mass number C.Isotopes III. Representing Atoms

37. A.The atomic number B.The mass number C.Isotopes 1.Atoms with the same number of protons, different number of neutrons III. Representing Atoms

38. A.The atomic number B.The mass number C.Isotopes 1.Atoms with the same number of protons, different number of neutrons 2.Isotopes have same properties, but different masses III. Representing Atoms

39. A.The atomic number B.The mass number C.Isotopes D.Notation III. Representing Atoms

40. Cl 37 17 Nuclide Symbol Notation

41. Cl 37 17 Element symbol Nuclide Symbol Notation

42. Cl 37 17 Atomic number Nuclide Symbol Notation

43. Cl 37 17 Mass number Nuclide Symbol Notation

44. Self Check – Ex. 1 Write the nuclide symbols for elements with these particles: Nuclide #1 22 protons 24 neutrons Nuclide #2 22 protons 26 neutrons

45. Self Check – Ex. 2 How many protons, neutrons, and electrons are in this element? Mo 95 42

46. Self Check – Ex. 3 How many protons, neutrons, and electrons are in this element? K 40

47. IV. Mass of atoms

48. A.Measured in amu IV. Mass of atoms

49. A.Measured in amu B.Protons and neutrons both weigh about 1 amu (neutrons are a bit more) IV. Mass of atoms

50. A.Measured in amu B.Protons and neutrons both weigh about 1 amu (neutrons are a bit more) C.The amu is defined as 1/12 the mass of carbon-12 IV. Mass of atoms

51. V. Atomic Mass

52. A.A weighted average of all the isotopes for a given element V. Atomic Mass

53. The older pennies have a mass of 3.0 g while the newer pennies have mass of 2.5 g. What is the average mass of these pennies? An analogy

54. The older pennies have a mass of 3.0 g while the newer pennies have mass of 2.5 g. What is the average mass of these pennies? An analogy 5 older 5 newer

55. What is the average mass of this sample? There are 4 older pennies (3.0 g) while there are 10 newer pennies have mass of 2.5 g. An analogy 4 older 10 newer

56. The older pennies have a mass of 3.0 g while the newer pennies have mass of 2.5 g. What is the average mass of these pennies? An analogy older newer

57. A.A weighted average of all the isotopes for a given element B.Formula V. Atomic Mass

58. % Isotope #1 x Mass of isotope #1 Atomic Mass % Isotope #2 x Mass of isotope #2 % Isotope #3 x Mass of isotope #3 + + all other isotopes + Atomic mass =

59. Self Check – Ex. 4 Use the following to find the atomic mass for chlorine. Chlorine-35 75.53 % 34.969 amu Chlorine-37 24.47 % 36.966 amu

60. VI. Radioactive Decay

61. A.Some atoms spontaneously emit radiation VI. Radioactive Decay

62. A.Some atoms spontaneously emit radiation B.Atoms change their identities in the process VI. Radioactive Decay

63. A.Some atoms spontaneously emit radiation B.Atoms change their identities in the process C.Atoms undergo radioactive decay because their nuclei are unstable VI. Radioactive Decay

64. VII. Types of Radiation

65. A.Alpha radiation VII. Types of Radiation

66. A.Alpha radiation VII. Types of Radiation 1.Make unstable heavy nuclei lighter

67. A.Alpha radiation VII. Types of Radiation 1.Make unstable heavy nuclei lighter 2.This radiation is attracted to negative electric fields

68. A.Alpha radiation VII. Types of Radiation 1.Make unstable heavy nuclei lighter 2.This radiation is attracted to negative electric fields 3.Comprised of alpha particles

69. Alpha Particles Made of: 2 protons & 2 neutrons Charge: Mass: Symbol:

70. Alpha Particles Made of: 2 protons & 2 neutrons Charge: Mass: Symbol: 2 +

71. Alpha Particles Made of: 2 protons & 2 neutrons Charge: Mass: Symbol: 2 + 4 amu

72. Alpha Particles Made of: 2 protons & 2 neutrons Charge: Mass: Symbol: 2 + 4 amu He 4 2 α 4 2 or

73. B.Beta radiation VII. Types of Radiation

74. B.Beta radiation VII. Types of Radiation 1.Increases the proton to neutron ratio

75. B.Beta radiation VII. Types of Radiation 1.Increases the proton to neutron ratio 2.Radiation is attracted to positive electric field

76. B.Beta radiation VII. Types of Radiation 1.Increases the proton to neutron ratio 2.Radiation is attracted to positive electric field 3.Comprised of beta particles

77. Beta Particles Made of: An electron from the nucleus Charge: Mass: Symbol:

78. Beta Particles Made of: An electron from the nucleus Charge: Mass: Symbol: 1 -

79. Beta Particles Made of: An electron from the nucleus Charge: Mass: Symbol: 1 - 1/1840 amu

80. Beta Particles Made of: An electron from the nucleus Charge: Mass: Symbol: 1 - 1/1840 amu e-e- 0 β 0 or

81. C.Gamma radiation VII. Types of Radiation

82. C.Gamma radiation VII. Types of Radiation 1.These accompany alpha and beta radiation

83. C.Gamma radiation VII. Types of Radiation 1.These accompany alpha and beta radiation 2.Not deflected by electric field

84. C.Gamma radiation VII. Types of Radiation 1.These accompany alpha and beta radiation 2.Not deflected by electric field 3.Gamma rays are high energy radiation

85. Gamma Particles Made of: Energy (not matter) Charge: Mass: Symbol: none γ 0 0

86. VIII. Penetrating Ability

87. A.Alpha radiation penetrates the. VIII. Penetrating Ability

88. A.Alpha radiation penetrates the least. B.Gamma radiation penetrates the. VIII. Penetrating Ability

89. A.Alpha radiation penetrates the least. B.Gamma radiation penetrates the most. VIII. Penetrating Ability

90. IX. Writing Equations

91. A.Atomic numbers and mass numbers are conserved IX. Writing Equations

92. A.Atomic numbers and mass numbers are conserved B.Examples IX. Writing Equations

93. Self Check – Ex. 5 Complete the following nuclear equation. K Ca + ? K Ca + ? 40 19 40 20

94. Self Check – Ex. 6 Complete the following nuclear equation. Pu ? + α Pu ? + α 239 94 4 2