1. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Chapter 3 Atoms and Elements 3.1 Elements and Symbols 1

2. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Chemical Symbols represent name of element consist of one to two letters and start with capital 1-Letter Symbols 2-Letter Symbols C carbon Co cobalt N nitrogenCa calcium F fluorine Al aluminum O oxygen Mg magnesium 2

3. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Chapter 3 Atoms and Elements 3.2 The Periodic Table 3

4. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Groups and Periods On the periodic table, elements are arranged according to similar properties groups contain elements with similar properties in vertical columns periods are horizontal rows of elements 4

5. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Groups and Periods 5

6. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Periodic Table of Elements 6

7. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Group Numbers Group numbers use the letter A for representative elements (Groups 1A–8A) use the letter B for transition elements (Groups 3B–12B) 7

8. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Classification of Groups 8

9. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Metals, Nonmetals, and Metalloids The heavy zigzag line separates metals and nonmetals. Metals are located to the left. Nonmetals are located to the right. Metalloids are located along the heavy zigzag line between the metals and nonmetals. 9

10. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Metals, Nonmetals, and Metalloids and Periodic Table 10

11. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Properties of Metals, Nonmetals, and Metalloids Metals are shiny and ductile are good conductors of heat and electricity Nonmetals are dull, brittle, and poor conductors are good insulators Metalloids are better conductors than nonmetals, but not as good as metals are used as semiconductors and insulators 11

12. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Comparing a Metal, Nonmetal, and Metalloid 12

13. Chapter 3 Atoms and Elements 3.3 The Atom 13 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

14. Dalton's Atomic Theory In Dalton's atomic theory, atoms are tiny particles of matter of an element are similar to each other and different from other elements of two or more different elements combine to form compounds are rearranged to form new combinations in a chemical reaction 14 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

15. Subatomic Particles Electrical Charges Atoms contain subatomic particles. Protons have a positive (+) charge. Electrons have a negative (– ) charge. Neutrons are neutral. Like charges repel and unlike charges attract. 15 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

16. Rutherford's Gold Foil Experiment 16 In Rutherford’s gold foil experiment, positively charged particles were aimed at atoms of gold mostly went straight through the atoms were deflected only occasionally Conclusion: There must be a small, dense, positively charged nucleus in the atom that deflects positive particles that come close. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

17. Rutherford's Gold Foil Experiment 17 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

18. Structure of the Atom An atom consists of a nucleus that contains protons and neutrons electrons in a large, empty space around the nucleus 18 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

19. Mass of the Atom Atomic mass unit 1 atomic mass unit (amu) has a mass equal to 1/12 of the mass of the carbon-12 atom. a proton has a mass of about 1 (1.007) amu. a neutron has a mass of about 1 (1.008) amu. an electron has a very small mass, 0.000 549 amu. 19 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

20. Subatomic Particles in the Atom 20 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

21. Chapter 3 Atoms and Elements 3.4 Atomic Number and Mass Number 21 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

22. Atomic Number The atomic number is specific for each element is the same for all atoms of an element is equal to the number of protons in an atom appears above the symbol of an element in the Periodic Table Atomic Number Symbol 22 11 Na Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

23. Atomic Number = Protons in Atom For example, atomic number = number of protons: Atomic number H is 1; every H atom has one proton Atomic number of C is 6; every C atom has six protons Atomic number of Cu is 29; every Cu atom has 29 protons 23 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

24. Atoms Are Neutral For neutral atoms, the net charge is zero. number of protons = number of electrons Aluminum has 13 protons and 13 electrons. The net (overall) charge is zero. 13 protons (13+) + 13 electrons (13 – ) = 0 24 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

25. Mass Number 25 The mass number represents the number of particles in the nucleus is equal to the number of protons + the number of neutrons is always a whole number does not appear in the periodic table Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

26. Atomic Symbols and Subatomic Particles 26 Examples of number of subatomic particles for atoms: Atomic symbol 16 31 65 O P Zn 8 15 30 8 p + 15 p + 30 p + 8 n16 n 35 n 8 e - 15 e - 30 e - Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

27. Chapter 3 Atoms and Elements 3.5 Isotopes and Atomic Mass 27 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

28. Isotopes are atoms of the same element have different mass numbers have same number of protons but different numbers of neutrons 28 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

29. Atomic Symbols for Isotopes of Magnesium 29 Mass Numbers Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

30. Atomic Symbols for Isotopes of Magnesium 30 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

31. Atomic Mass Atomic mass is the weighted average of all naturally occurring isotopes of that element number on the periodic table below the chemical symbol with two decimal places 31 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

32. Calculating Atomic Mass To calculate atomic mass, use an experimental percent abundance of each isotope of the element multiply the percent abundance by the atomic mass of that isotope sum the total mass of each isotope 32 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

33. Calculating Atomic Mass To calculate atomic mass of Cl, use experimental data for both isotopes of Cl: Isotope atomic mass x % abundance 35 Cl 34.97 amu x 75.76 = 26.49 amu 100 37 Cl 36.97 amu x 24.24 = 8.962 amu 100 Atomic mass of Cl = 35.45 amu 33 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

34. Learning Check Lithium consists of two naturally occurring isotopes, 6 Li and 7 Li. Use the periodic table to predict which isotope is the most prevalent one. Periodic table atomic mass of lithium is 6.941 amu. 34 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

35. Solution Lithium consists of two naturally occurring isotopes, 6 Li and 7 Li. Use the periodic table to predict which isotope is the most prevalent one. Periodic table atomic mass of lithium is 6.941 amu. 6 Li and 7 Li Since the total atomic mass of 7 Li is closer to 7, the mass number of 7 Li, the most prevalent isotope is 7 Li. 35 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

36. Learning Check Gallium is an element found in lasers used in compact disc players. In a sample of gallium, there is 60.10% of 69 Ga (atomic mass 68.926) atoms and 39.90% of 71 Ga (atomic mass 70.925) atoms. What is the atomic mass of gallium? 36 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

37. Solution 69 Ga 68.926 amu x 60.10 = 41.42 amu (from 69 Ga) 100 71 Ga 70.925 amu x 39.90 = 28.30 amu (from 71 Ga) 100 Atomic mass Ga = 69.72 amu 37 31 Ga 69.72 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

38. Chapter 3 Atoms and Elements 3.6 Electron Energy Levels 38 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

39. Electromagnetic Spectrum The electromagnetic spectrum shows the arrangement of wavelengths of electromagnetic radiation, with the visible range from 700 to 400 nm. 39 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

40. Elements Have a Unique Atomic Spectrum When light from an element that is heated passes through a prism, it separates into a unique set of distinct lines of color called an atomic spectrum. 40 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

41. Electron Energy Levels Energy levels are assigned numbers n = 1, 2, 3, 4, and so on increase in energy as the value of n increases are like the rungs of a ladder, with the lower energy levels nearer the nucleus 41 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

42. Energy Levels Energy levels have a maximum number of electrons equal to 2n 2. Energy levelMaximum number of electrons n = 12(1) 2 = 2(1) = 2 n = 22(2) 2 = 2(4) = 8 n = 32(3) 2 = 2(9) = 18 42 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

43. Changes in Electron Energy Level Electrons move to a higher energy level when it absorbs energy. When electrons fall back to a lower energy level, light is emitted. The energy emitted or absorbed is equal to the differences between the two energy levels. 43 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

44. Changes in Electron Energy Level 44 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

45. Electron Arrangements in Period 1 Period 1 H1 electron in 1 st energy level. He2 electrons in 1 st energy level. 45 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

46. Electron Arrangements in Period 2 Period 2 Energy Level1 st 2 nd Li21 Be22 B23 C24 N25 O26 F27 Ne28 46 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

47. Electron Arrangements in Period 3 Period 3 Energy Level1 st 2 nd 3 rd Na 2 8 1 Mg 2 8 2 Al 2 8 3 Si 2 8 4 P 2 8 5 S 2 8 6 Cl 2 8 7 Ar 2 8 8 47 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

48. Electron Arrangements in Period 4 Period 4 Energy Level 1 st 2 nd 3 rd 4 th K 2 8 8 1 Ca 2 8 8 2 48 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

49. Electron Arrangements Beyond 20 Energy Level 1 st 2 nd 3 rd 4 th 5 th 6 th 7 th Number of Electrons 28 18 32 32 18 8 Electron arrangements are written as: O = 2,6 P = 2,8,5 Ca= 2,8,8,2 49 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

50. Learning Check Write the electron arrangement for the following elements: C Si O N 50 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

51. Solution Write the electron arrangement for the following elements: C=2,4 Si=2,8,4 O=2,6 N=2,5 51 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

52. Chapter 3 Atoms and Elements 3.7 Trends in Periodic Properties 52 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

53. Group Number and Valence Electrons For representative elements in Groups 1A–8A, chemical properties are due to the number of valence electrons. Valence electrons are the number of electrons in the outermost energy level. The group number gives the number of valence electrons for the representative elements. 53 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

54. Group Number and Valence Electrons Group Number # Valence Electrons 1A1 2A2 3A3 4A4 5A5 6A6 7A7 8A8 54 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

55. Electron-Dot Symbols Electron-dot symbols are also known as Lewis structures represent the valence electrons as dots placed on sides of symbol For example, Al = 2,8,3 Three valence electrons are represented as dots: 55 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

56. Electron-Dot Symbol for Mg Possible electron-dot symbols for magnesium, with the electron arrangement of 2,8,2, include 2 valence electrons, represented as dots can be drawn in more than one way 56 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

57. Electron-Dot Symbols for Selected Elements 57 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

58. Atomic Size Atomic size is determined by the atom’s atomic radius, the distance between nucleus and outermost electrons increases for representative elements from top to bottom of the periodic table decreases within a period due to increased number of protons in nucleus 58 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

59. Atomic Size 59 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

60. Atomic Size 60 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

61. Ionization Energy Ionization energy is the energy required to remove one of the outermost electrons from an atom Na(g) + energy (ionization)  Na + (g) + e − decreases down a group, increases across a period from left to right 61 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

62. Ionization Energy 62 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

63. Metallic Character An element with metallic character is one that loses electrons easily. Metallic character is more prevalent in metals on left side of periodic table is less for nonmetals on right side of periodic table that do not lose electrons easily 63 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

64. Metallic Character 64 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.

65. Summary of Trends in Periodic Table 65 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc.