1. Do Now Activity Sit down quietly in your assigned seat and begin writing 3 to 4 sentences about what is an atom and how atoms relate to elements. (8 minutes to complete this) This should be written in your notebook for this class or loose leaf paper if you do not have a note book yet. LecturePLUS Timberlake1

2. 2 Chemistry Luskin Academy Mr. Berlin Introduction to Chemistry Measurements Significant figures The Atom Atomic Number and Mass Number Isotopes

3. Measurements Measured Numbers and Significant Figures

4. Measured Numbers When you use a measuring tool is used to determine a quantity such as your height or weight. These type of numbers are called simply measured numbers.

5. Reading a Meterstick. l 2.... I.... I 3....I.... I 4.. cm First digit (known)= 2 2.?? cm Second digit (known)= 0.7 2.7? cm Third digit (estimated) between 0.05- 0.07 Length reported=2.75 cm or2.76 cm or2.77 cm

6. Known + Estimated Digits Known digits 2 and 7 are 100% certain The third digit 6 is estimated (uncertain) In the reported length, all three digits (2.76 cm) are significant including the estimated one

7. Learning Check. l 8.... I.... I 9....I.... I 10.. cm What is the length of the line? 1) 9.3 cm 2) 9.32 cm 3) 9.33 cm How your answer compare with your neighbor ’ s answer? Why or why not?

8. Solution. l 8.... I.... I 9....I.... I 10.. cm Estimate to the hundreth ’ s place (0.01 cm) 2) 9.32 cm 3) 9.33 cm The estimated digit may be slightly different. Both readings are acceptable.

9. Learning Check l 5.... I.... I 6....I.... I 7.. cm What is the length of the line? 1) 6.0 cm 2) 6.09 cm 3) 6.60 cm

10. Solution l 5.... I.... I 6....I.... I 7.. cm Estimate to the hundreth ’ s place (0.01 cm). The reading is between 6.0 and 6.1. You may have estimated 6.07 cm as well. 2) 6.09 cm

11. Zero as a Measured Number. l 3.... I.... I 4.... I.... I 5.. cm What is the length of the line? First digit 4.?? cm Second digit 4.6? cm Last (estimated) digit is 4.60 cm (not to the left or right of.5)

12. Exact Numbers Obtained when you count objects 2 soccer balls 1 watch 4 pizzas Obtained from a defined relationship 1 foot = 12 inches 1 meters = 100 cm Not obtained with measuring tools

13. Learning Check A. Exact numbers are obtained by 1. measuring 2. counting 3. definition B. Measured numbers are obtained by 1. measuring 2. counting 3. definition

14. Solution A. Exact numbers are obtained by 2. counting 3. definition B. Measured numbers are obtained by 1. Using a measuring tool

15. Learning Check Classify each of the following as an exact (1) or a measured (2) number. A.___Gold melts at 1064°C B.___1 yard = 3 feet C.___A red blood cell with diameter 6 x 10 -4 cm D.___There were 6 hats on the shelf E.___A can of soda contains 355 mL of soda

16. Solution Classify each of the following as an exact (1) or a measured(2) number. Give reason. A. 2 Requires a thermometer(measuring tool) B. 1 From a definition in U.S. system C. 2 Need measuring tool to determine D. 1 Counted the hats E. 2 Measured

17. Timberlake lecture plus17 Measurements Significant Figures in Calculations

18. Timberlake lecture plus18 Significant Figures in Measurement The numbers reported in a measurement are limited by the measuring tool Significant figures in a measurement include the known digits plus one estimated digit

19. Timberlake lecture plus19 Counting Significant Figures Number of Significant Figures 38.15 cm4 5.6 ft2 65.6 lb___ 122.55 m___ Complete: All non-zero digits in a measured number are (significant or not significant).

20. Timberlake lecture plus20 Leading Zeros Number of Significant Figures 0.008 mm1 0.0156 oz3 0.0042 lb____ 0.000262 mL ____ Complete: Leading zeros in decimal numbers are (significant or not significant).

21. Timberlake lecture plus21 Sandwiched Zeros Number of Significant Figures 50.8 mm3 2001 min4 0.702 lb____ 0.00405 m ____ Complete: Zeros between nonzero numbers are (significant or not significant).

22. Timberlake lecture plus22 Trailing Zeros Number of Significant Figures 25,000 in. 2 200 yr1 48,600 gal3 25,005,000 g ____ Complete: Trailing zeros in numbers without decimals are (significant or not significant) if they are serving as place holders.

23. Timberlake lecture plus23 Learning Check A. Which answers contain 3 significant figures? 1) 0.4760 2) 0.00476 3) 4760 B. All the zeros are significant in 1) 0.00307 2) 25.300 3) 2.050 x 10 3 C. 534,675 rounded to 3 significant figures is 1) 535 2) 535,000 3) 5.35 x 10 5

24. Timberlake lecture plus24 Solution A. Which answers contain 3 significant figures? 2) 0.00476 3) 4760 B. All the zeros are significant in 2) 25.300 3) 2.050 x 10 3 C. 534,675 rounded to 3 significant figures is 2) 535,000 3) 5.35 x 10 5

25. Timberlake lecture plus25 Learning Check In which set(s) do both numbers contain the same number of significant figures? 1) 22.0 and 22.00 2) 400.0 and 40 3) 0.000015 and 150,000

26. Timberlake lecture plus26 Solution In which set(s) do both numbers contain the same number of significant figures? 3) 0.000015 and 150,000

27. Timberlake lecture plus27 State the number of significant figures in each of the following: A. 0.030 m 1 2 3 B. 4.050 L 2 3 4 C. 0.0008 g 1 2 4 D. 3.00 m 1 2 3 E. 2,080,000 bees 3 5 7 Learning Check SF3

28. Timberlake lecture plus28 A. 0.030 m2 B. 4.050 L4 C. 0.00008 g1 D. 3.00 m 3 E. 2,080,000 bees3 Solution

29. Exit Question…. Remain in your seats until the bell rings. “What are significant figures in your own words? How are zeros counted in regards to significant figures? What did you learn about measuring tools and how accurate they can be?” LecturePLUS Timberlake29

30. Do Now activity…. Answer the following: How many significant figures in; a) 0.00065 cm, b) 4.50 cm, c) 7600 feet, d) 3406.05 mm, e) 550 ml, f) 0.780 km Which would be the proper tool to measure 4.5 ml of water; a) 100 ml graduated cylinder, b) 10 ml graduated cylinder, 10 ml beaker For measuring a room in feet a) meter stick, b) tape measure, c) ruler 30

31. Timberlake lecture plus31 Significant Numbers in Calculations A calculated answer cannot be more precise than the measuring tool. A calculated answer must match the least precise measurement. Significant figures are needed for final answers from 1) adding or subtracting 2) multiplying or dividing

32. Timberlake lecture plus32 Adding and Subtracting The answer has the same number of decimal places as the measurement with the fewest decimal places. 25.2 one decimal place + 1.34 two decimal places 26.54 answer 26.5 one decimal place

33. Timberlake lecture plus33 Learning Check In each calculation, round the answer to the correct number of significant figures. A. 235.05 + 19.6 + 2.1 = 1) 256.75 2) 256.83) 257 B. 58.925 - 18.2= 1) 40.725 2) 40.733) 40.7

34. Timberlake lecture plus34 Solution A. 235.05 + 19.6 + 2.1 = 2) 256.8 B. 58.925 - 18.2= 3) 40.7

35. Timberlake lecture plus35 Multiplying and Dividing Round (or add zeros) to the calculated answer until you have the same number of significant figures as the measurement with the fewest significant figures.

36. Timberlake lecture plus36 Learning Check A. 2.19 X 4.2 = 1) 9 2) 9.2 3) 9.198 B. 4.311 ÷ 0.07 = 1) 61.58 2) 62 3) 60 C. 2.54 X 0.0028 = 0.0105 X 0.060 1) 11.32) 11 3) 0.041

37. Timberlake lecture plus37 Solution A. 2.19 X 4.2 = 2) 9.2 B. 4.311 ÷ 0.07 = 3) 60 C.2.54 X 0.0028 = 2) 11 0.0105 X 0.060 Continuous calculator operation = 2.54 x 0.0028  0.0105  0.060

38. Precision, accuracy and measurements https://www.youtube.com/v/b38hFWvEjwI LecturePLUS Timberlake38

39. 39 Atomic Theory Atoms are building blocks of elements. Remember how tiny an atom is. Billions of atoms are on a pencil tip. Similar (same) atoms in each element Different from atoms of other elements Two or more different atoms bond in simple ratios to form compounds (Molecules)

40. 40 Subatomic Particles: atoms are made of smaller particles. ParticleSymbol Charge Relative Mass Electron e - 1- 0 Proton p + + 1 Neutron n0 1

41. 41 Location of Subatomic Particles Atom size about 10 -8 cm Neutron (0) Proton (+ ) Electron (-)

42. Bohr Atomic Model LecturePLUS Timberlake42

43. Modern Atomic Model LecturePLUS Timberlake43

44. Atomic model overview https://www.youtube.com/v/UDIprICe9kg LecturePLUS Timberlake44

45. LecturePLUS Timberlake45 Atomic Number Atomic number is the number of protons in an atom (the positive sub-atomic particle)

46. LecturePLUS Timberlake46 Atomic Number - The periodic table is arranged by the atomic number. 11 Na Atomic Number Symbol

47. LecturePLUS Timberlake47 All atoms of an element have the same number of protons 11 Na 11 protons Sodium

48. LecturePLUS Timberlake48

49. LecturePLUS Timberlake49

50. Periodic Table LecturePLUS Timberlake50 https://www.youtube.com/v/IsB Zx0tv6dQ https://www.youtube.com/v/k6 NlVM5YBswhttps://www.youtube.com/v/k6 NlVM5YBsw

51. LecturePLUS Timberlake51

52. LecturePLUS Timberlake52 Learning Check State the number of protons for atoms of each of the following: A. Nitrogen 1) 5 protons 2) 7 protons 3) 14 protons B. Sulfur 1) 32 protons 2) 16 protons 3) 6 protons C. Barium 1) 137 protons 2) 81 protons 3) 56 protons

53. LecturePLUS Timberlake53 Solution State the number of protons for atoms of each of the following: A. Nitrogen 2) 7 protons B. Sulfur 2) 16 protons C. Barium 3) 56 protons

54. LecturePLUS Timberlake54 Mass Number Counts the number of protons and neutrons in an atom

55. LecturePLUS Timberlake55 Atomic Symbols Show the mass number and atomic number Give the symbol of the element mass number 23 Na sodium-23 atomic number 11

56. LecturePLUS Timberlake56 Number of Electrons An atom is neutral on the Periodic Table The net charge is zero Number of protons = Number of electrons Atomic number = Number of electrons

57. LecturePLUS Timberlake57 Subatomic Particles in Some Atoms 1631 65 O P Zn 815 30 8 p + 15 p + 30 p + 8 n16 n35 n 8 e - 15 e - 30 e -

58. LecturePLUS Timberlake58 Isotopes Atoms with the same number of protons, but different numbers of neutrons. Atoms of the same element (same atomic number) with different mass numbers Isotopes of chlorine 35 Cl 37 Cl17 chlorine - 35 chlorine - 37

59. LecturePLUS Timberlake59 Learning Check Naturally occurring carbon consists of three isotopes, 12 C, 13 C, and 14 C. State the number of protons, neutrons, and electrons in each of these carbon atoms. 12 C 13 C 14 C 6 6 6 #p _______ _______ _______ #n _______ _______ _______ #e _______ _______ _______

60. LecturePLUS Timberlake60 Solution 12 C 13 C 14 C 6 6 6 #p 6 6 6 #n 6 7 8 #e 6 6 6

61. LecturePLUS Timberlake61 Learning Check An atom of zinc has a mass number of 65. A.Number of protons in the zinc atom 1) 302) 353) 65 B.Number of neutrons in the zinc atom 1) 302) 353) 65 C. What is the mass number of a zinc isotope with 37 neutrons? 1) 372) 653) 67

62. LecturePLUS Timberlake62 Solution An atom of zinc has a mass number of 65. A.Number of protons in the zinc atom 1) 30 B.Number of neutrons in the zinc atom 2) 35 C. What is the mass number of a zinc isotope with 37 neutrons? 3) 67

63. LecturePLUS Timberlake63 Learning Check Write the atomic symbols for atoms with the following: A. 8 p +, 8 n, 8 e - ___________ B.17p +, 20n, 17e - ___________ C. 47p +, 60 n, 47 e - ___________

64. LecturePLUS Timberlake64 Solution 16 O A. 8 p +, 8 n, 8 e - 8 B.17p +, 20n, 17e - 37 Cl 17 C. 47p +, 60 n, 47 e - 107 Ag 47

65. LecturePLUS Timberlake65 Atomic Mass on the Periodic Table 11 Na 22.99 Atomic Number Symbol Atomic Mass

66. LecturePLUS Timberlake66 Atomic Mass Atomic mass is the weighted average mass of all the atomic masses of the isotopes of that atom.

67. LecturePLUS Timberlake67 Example of an Average Atomic Mass Cl-35 is about 75.5 % and Cl-37 about 24.5% of natural chlorine. 35 x 75.5 = 26.4 100 35.5 37 x 24.5 = 9.07 100

68. Exit Question…. What is a proton? What is a neutron? What is an electron? What is atomic number? How is the periodic table arranged? Once you are done remain in your seats and turn in your exit question as you leave the classroom. LecturePLUS Timberlake68