1. Chapter 3 pages 66 - 871 Modern Chemistry Chapter 3 Atoms: the building block of matter

2. Chapter 3 pages 66 - 872 Section 1 Atoms: From Philosophical Idea to Scientific Theory

3. Chapter 3 pages 66 - 873 Foundation of Chemical Atomic Theory Law of Conservation of Mass –Mass is neither created or destroyed during ordinary chemical reactions or physical changes

4. Chapter 3 pages 66 - 874 Law of Conservation of Mass Image p. 69*

5. Chapter 3 pages 66 - 875 Law of Conservation of Mass Image p. 69*

6. Chapter 3 pages 66 - 876 Foundation of Chemical Atomic Theory Law of Definite Proportions –A chemical compound contains the same elements in exactly the same proportions by mass regardless of the size of the sample or the source of the compound.

7. Chapter 3 pages 66 - 877 Foundation of Chemical Atomic Theory Law of Multiple Proportions –If two or more different compounds are composed of the same two elements then the ratio of the masses of the second element combined with a certain mass of the first element is always a ratio of small whole numbers.

8. Chapter 3 pages 66 - 878 Law of Multiple Proportions Image p. 69*

9. Chapter 3 pages 66 - 879 Dalton’s Atomic Theory 1. All matter is composed of extremely small particles called atoms

10. Chapter 3 pages 66 - 8710 Dalton’s Atomic Theory 2. Atoms of a given element are identical in size, mass and other properties; atoms of different elements differ in size, mass and other properties.

11. Chapter 3 pages 66 - 8711 Dalton’s Atomic Theory 3. Atoms cannot be subdivided, created or destroyed.

12. Chapter 3 pages 66 - 8712 Dalton’s Atomic Theory 4. Atoms of different elements combine in simple whole-number ratios to form chemical compounds.

13. Chapter 3 pages 66 - 8713 Dalton’s Atomic Theory 5. In chemical reactions, atoms are combined, separated or rearranged.

14. Chapter 3 pages 66 - 8714 Modern Atomic Theory Leucippus Democritus Atomic Theory Tested by experiment and modified with new discoveries and experiments

15. Chapter 3 pages 66 - 8715 Section 2 The Structure of the Atom

16. Chapter 3 pages 66 - 8716 Discovery of the Electron Cathode Ray Tube Experiment - Thompson Observations –Cathode Rays are deflected a magnetic field. –Cathode rays are deflected from a negatively charged object. –Charge to mass ratio is always the same for the cathode rays.

17. Chapter 3 pages 66 - 8717 Discovery of the Electron Cathode Ray Tube Experiment - Thompson Conclusion –Cathode rays are composed of negatively charged particles –Named “electrons”

18. Chapter 3 pages 66 - 8718 Discovery of the Electron Oil Drop Experiment - Millikan –Measured the charge of the electron –Calculated the mass of an electron 9.109 x 10 -31 kg

19. Chapter 3 pages 66 - 8719 Discovery of the Electron Inferences –Atoms are neutral, so there must be a positive charge. –Electrons are small, so there must be other particles.

20. Chapter 3 pages 66 - 8720 Discovery of the Electron Plum Pudding Model –Negative electrons were spread evenly throughout the positive charge.

21. Chapter 3 pages 66 - 8721 Discovery of the Electron

22. Chapter 3 pages 66 - 8722 Discovery of the Atomic Nucleus Gold Foil Experiment – Rutherford et. al –Hypothesis: Alpha particles would pass through with slight deflection. –Observation: 1 in 8000 particles were deflected back to the source. –Conclusion: The atom contains a small densely packed bundle of matter with a positive charge –Named the “nucleus”

23. Chapter 3 pages 66 - 8723 Gold Foil Animation Insert Glencoe Disk 1 and click on picture for animation.

24. Chapter 3 pages 66 - 8724 Gold Foil Animation

25. Chapter 3 pages 66 - 8725 Gold Foil Experiment Image p. 75

26. Chapter 3 pages 66 - 8726 Discovery of the Atomic Nucleus Relative size of the nucleus

27. Chapter 3 pages 66 - 8727 Composition of The Atomic Nucleus Nuclei contain protons and neutrons Neutral because number of protons equal number of electrons Each element has a different number of protons in their nucleus –The number of protons determines the atom’s identity Nuclear forces hold protons & neutrons together

28. Chapter 3 pages 66 - 8728 Properties of Subatomic Particles p. 76

29. Chapter 3 pages 66 - 8729 While the number of protons in the nucleus defines an element's identity, variations on the number of neutrons in the nucleus give rise to different isotopes of the same element. Isotopes of hydrogen

30. Chapter 3 pages 66 - 8730 Gold Foil Experiment Photo

31. Chapter 3 pages 66 - 8731 Gold Foil Experiment Photo

32. Chapter 3 pages 66 - 8732 Thompson and Rutherford Photo

33. Chapter 3 pages 66 - 8733 Section 2 Homework Ch 3 Sec 2 Review Page 76 #1-5

34. Chapter 3 pages 66 - 8734 Section 3 Counting Atoms

35. Chapter 3 pages 66 - 8735 Atomic Number The number of protons of each atom of that element Identifies the element

36. Chapter 3 pages 66 - 8736 Isotopes Atoms of the same element that have different masses equals the isotope Isotopes do not differ significantly in their chemical behavior

37. Chapter 3 pages 66 - 8737 Mass Numbers Mass numbers = # of p + + # of n 0 of a specific isotope

38. Chapter 3 pages 66 - 8738 Designating Isotopes Hyphen notation –name of element – mass number –Hydrogen – 3 Nuclear symbol mass number atomic number

39. Chapter 3 pages 66 - 8739 Number of neutrons in an atom neutrons = mass number – atomic number (This is how to calculate isotopes…) Nuclide – a general term for a specific isotope of an element **Practice Problems page 87 #2-3

40. Chapter 3 pages 66 - 8740 Relative Atomic Mass One atom, carbon-12, is set as a standard All masses are expressed in relation to this standard 1 atomic mass unit = 1/12 the mass of a carbon-12 atom

41. Chapter 3 pages 66 - 8741 Relative Atomic Mass Examples –Hydrogen – 1 = 1.007825 amu –Oxygen – 16 = 15.994915 amu –Magnesium – 24 = 23.985042 amu p + = 1.007276 amu, n 0 = 1.008665 amu, e - = 0.0005486 amu Relative mass and mass number are close in value but not the same

42. Chapter 3 pages 66 - 8742 Average Atomic Mass The weighted average of the atomic masses of the naturally occurring isotopes of an element Example –Copper Cu-63:.6915 x 62.93 amu = 43.52 Cu-65:.3085 x 64.93 amu = 20.03 63.55 amu percent relative mass

43. Chapter 3 pages 66 - 8743 The Mole An amount of a substance that contains as many particles as there are atoms in exactly 12 g carbon-12. Similar to a dozen or a pair or a gross 6.022 x 10 23 carbon-12 atoms = 12 grams of carbon-12 Avogadro’s number = 6.022 x 10 23 particles

44. Chapter 3 pages 66 - 8744 Molar mass The mass of one mole of a pure substance Unit = g/mol On the periodic table, use 4 sig. figs.

45. Chapter 3 pages 66 - 8745 Gram-Mole Conversions The conversion factor for gram-mole conversion is molar mass. What is the mass, in grams, of 3.50 moles of Cu? –222 grams Cu OR g mol g

46. Chapter 3 pages 66 - 8746 Practice Problems page 85 1.What is the mass in grams of 2.25 mol of the element iron? 2.What is the mass in grams of 0.357 mol of the element potassium? 3.What is the mass in grams of 0.0135 mol of the element sodium? 4.What is the mass in grams of 16.3 mol of the element nickel? p. 85 126 g Fe 14.7 g K 0.310 g Na 957 g Ni

47. Chapter 3 pages 66 - 8747 Conversions Image p. 84

48. Chapter 3 pages 66 - 8748 Gram-Mole Conversions The conversion factor for gram-mole conversion is molar mass. A Chemist produced 11.9 g of Al. How many moles of Al were produced? –0.411 moles Al OR g mol g

49. Chapter 3 pages 66 - 8749 Practice Problems page 85 1.How many moles of calcium are in 5.00 g of calcium? 2.How many moles of gold are in 3.60 x 10 -5 g of gold? 3.How many moles of zinc are in 0.535 g of zinc? p. 85 0.125 mol Ca 1.83 x 10 -7 mol Au 8.18 x 10 -3 mol Zn

50. Chapter 3 pages 66 - 8750 Conversions with Avogadro’s Number The conversion factor for particle-mole conversion is Avogadro’s number. How many moles of silver are in 3.01 x 10 23 atoms of silver –0.500 moles Ag OR 6.022x10 23 atoms 1 mol 6.022x10 23 atoms 1 mol

51. Chapter 3 pages 66 - 8751 Practice Problems page 86 1.How many moles of lead are 1.50 x 10 12 atoms of lead? 2.How many moles of tin are in 2500 atoms of tin? 3.How many atoms of aluminum are in 2.75 mol of aluminum? p. xx 2.49 x 10 -12 mol Pb 4.2 x 10 -21 mol Sn 1.66 x 10 24 atoms Al

52. Chapter 3 pages 66 - 8752 Conversions with Avogadro’s Number The conversion factor for particle-mole conversion is Avogadro’s number. What is the mass, in grams, of 1.20x10 18 atoms of Cu? –1.27 x 10 -4 g Cu OR 6.022x10 23 atoms 1 mol 6.022x10 23 atoms 1 mol

53. Chapter 3 pages 66 - 8753 Practice Problems page 87 1.What is the mass in grams of 7.5 x 10 15 atoms of nickel? 2.How many atoms of sulfur are in 4.00 g of sulfur? 3.What mass of gold contains the same number of atoms as 9.0 g of aluminum? p. xx 7.3 x 10 -7 g Ni 7.51 x 10 22 atoms S 66 g Au

54. Chapter 3 pages 66 - 8754 Conversions Image p. 84

55. Chapter 3 pages 66 - 8755 Section 1 Homework Section Review Page 87 #1-7