1. Chapter Two Atoms and the Periodic Table Fundamentals of General, Organic and Biological Chemistry 7th Edition James E. Mayhugh Copyright © 2010 Pearson Education, Inc.

2. 2.1 Modern Atomic Theory ► ►Atoms are composed of tiny subatomic particles called protons, neutrons, and electrons. ► ►Atomic masses are relative … one atom is assigned a mass, and all others are measured relative to it. ► ►The version of carbon that contains 6 protons and 6 neutrons is that atom, and it is assigned a mass of exactly 12 atomic mass units (amu).

3. ► ►Both protons and neutrons have a mass close to one amu. ► ►Electrons are ~2000 times lighter than protons and neutrons, so their relative mass is ~ 0 amu ► ►Protons and electrons have electrical charges that are equal in magnitude but opposite in sign.

4. ► ►The protons and neutrons are packed closely together in a dense core called the nucleus. Surrounding the nucleus, the electrons move about rapidly through a large volume of space. ►The relative size of a nucleus in an atom is the same as that of a pea in the middle of this stadium.

5. 2.2 Elements and Atomic Number ► ►Atomic Number (Z): The number of protons in each atom of an element. ► ► It’s THE characteristic that defines which element it is. ► ►Atoms are neutral …# of protons and # of electrons are equal. ► ► # of neutrons is usually NOT equal to protons and electrons!! ► ►Mass Number (A): The total number of protons plus neutrons in an atom.

6. 2.3 Isotopes and Atomic Weight   Isotopes: Atoms with identical atomic numbers (Z) but different mass numbers (A) are called isotopes.   # of protons are the same, but # of neutrons are different   Isotopes of a given element have identical CHEMICAL properties, but different NUCLEAR properties.

7. Isotopes of Hydrogen

8. Isotope Symbols

9. Other methods of conveying the same information as Hydrogen – 3 H – 3 3H3H

10. How many protons, electrons, and neutrons are in the atom shown below? 1. 92p, 92e, 143n 2. 92p, 43e, 235n 3. 92p, 92e, 235n 4. 235p, 235e, 143n

11.   Atomic Weight (Mass): The weighted average mass of all isotopes of that element   It’s the “decimal” number on the periodic table   But no single atom of that element has that weight.   Atomic weight=  (isotope fractional abundance)*(isotope mass)

12.   Atomic weight=  (isotope fractional abundance)*(isotope mass)   Gallium has two naturally occurring isotopes: 60.4% is Ga-69, (mass = 68.9257 amu), and 39.6% is Ga-71, (mass = 70.9248 amu). Calculate the average atomic weight for gallium.

13. 2.4 The Periodic Table ► ►elements are arranged by increasing atomic number … ► ►into seven horizontal rows, called periods… ► ►and 18 vertical columns, called groups. ► ►The elements in a given group have similar chemical properties.

14. The Periodic Table

15. The groups on the periodic table are divided into three main categories. ► ►Main Groups: The two groups on the far left (1-2) and the six on the far right (13-18) are the main groups.

16. The groups on the periodic table are divided into three main categories. ► ►Transition Metal Groups: Elements in the groups numbered 3 through 12.

17. The groups on the periodic table are divided into three main categories. ► ►Inner Transition Metal Groups: The 14 groups shown at the bottom of the table that are not numbered containing the Lanthanides and the Actinides.

18. 2.5 Names of Different Groups   Group 1A or 1 Alkali metals

19. 2.5 Names of Different Groups   Group 2A or 2 Alkaline Earth metals

20. 2.5 Names of Different Groups   Group 7A or 17 Halogens

21. 2.5 Names of Different Groups   Group 8A or 18 Noble Gases

22. 2. 6 Electronic Structure of Atoms Quantum mechanical model ► ►Gives specific information about what the electrons are “doing” in the atom ► ►And where their “playgrounds” are

23. The “planetary” model - too simplistic. Electrons do NOT orbit the nucleus like planets orbit the sun. 7.5

24. Quantum Mechanical Model Better model: electrons in a PLAYGROUND with a fence where the train track was. We call each “playground” an orbital 7.5

25. Electronic Structure of Atoms ► ►Old school:

26. ► ►New school: electrons flying around in “orbitals” that extends OUT to where that circle was drawn.

27. Electron Orbitals A 3-D region in space where you are most likely to find a given electron If you could see the electron, this region would look like a 3-D “blur”… we also call this an “electron cloud” There are LOTS of these “electron playgrounds” in an atom… and they overlap! 7.5

28. 2. 6 Electronic Structure of Atoms OK… now for the “Nitty Gritty” of how electrons are organized in an atom:

29. ► ►The electrons “fly around” in a 3-D region called an orbital. ► ► 2 Electrons MAX can “fit” into any given orbital, and they spin in opposite directions. ► ► The SIZE of the orbital is determined by the ENERGY SHELL of the electron ► ► The SHAPE of the orbital is determined by the ENERGY SUBSHELL of the electron.

30. Energy Shells ► ►(Also known as energy levels) ► ►The higher the energy level of the electron, the bigger its shell ► ►Shells are made up of one or more subshells.

31. ► ►(Also known as energy sublevels) ► ►The SUBshell is the set of “playgrounds” (orbitals) in a given shell. ► ►Therefore, they all extend the same distance from the nucleus as each other Energy SUBshells

32. ► ►Orbitals (the electron “playgrounds”) of a given subshell all have identical (or at least very similar) shapes. ► ►There are four different types of subshells, labeled as: s, p, d, and f, ► ►each with different shapes Energy SUBshells

33. ► ►“Shapes” of orbitals in a given subshell:

34. ► ►Electrons “fly” around the nucleus in “playgrounds” called… ► ►Orbitals, (which can hold no more than 2 electrons, each) whose shapes are determined by which… ► ►Subshell that the electron is in, whose size is determined by which… ► ►Shell the electron is in. ► ►And an atom is simply a collection of electrons that are in these shells/subshells/orbitals ► ►But WAIT… there’s MORE!!! So… what do we have so far?

35. ► ►A shell has a number of subshells equal to its shell number. ► ►The first subshell in ANY shell is always “s” because it is lowest in energy. ► ►The next subshell is always “p”, etc. # of Subshells per Shell

36. ► ►The more “complex” the subshell shape, the more orbitals that subshell has. # of Orbitals per Subshell

37. ► ►The more “complex” the subshell shape, the more orbitals that subshell has. ► ►The number of orbitals within a subshell increases by odd numbers. # of Orbitals per Subshell

38. S Subshell S Subshell 7.5 - Only one orbital… so the orbital is the whole subshell!

39. p Subshell Orbital Orientations 7.5 - 3 double lobe orbitals in a p subshell… one along each axis

40. d Sublevel Orbital Orientations 7.5 - The more complicated the shape, the more possible orbitals!

41. f Sublevel Orbital Orientations 7.5 - The more complicated the shape, the more possible orientations!

42. Summary!!

43. 2.7 Orbital Diagrams and Electron Configurations Orbital Diagram: A “tool” used to show location and other information about each electron in an atom Electron Configuration: A “shorthand” version of an orbital diagram

44. 2.7 Orbital Diagrams and Electron Configurations “Quantum World” Rules 1. 1.Electrons occupy the lowest energy orbitals available first. 2. 2.2 electrons, max, per orbital 3. 3.For all p, d and f subshells, each orbital gets one electron (spinning the SAME direction) before any orbital gets two.

45. Order of energy sublevels: ► ►Some overlap in energy levels occurs starting with shells 3 and 4.

46. You will need to build a mnemonic device for remembering the order of the energy levels in an atom.

47. Orbital Diagram and Electron Configuration Practice

48. “Shorthand” electron configuration for lead (Pb) 1.Write the symbol for the previous noble gas in brackets: [Xe] 2.“Pick up” the configuration on the diagonal chart from the “s” subshell of the row number lead is in: [Xe] 6s 3.Subtract # of electrons in Xe from those in lead, and place those remaining electrons: 28 more e - needed [Xe] 6s 2 4f 14 5d 10 6p 2

49. Valence electron: An electron in the outermost (valence) shell of an atom. These electrons are the ones that would interact first with the electrons of a different atom… …so they are the most important ones to “keep track of”. (as opposed to “inner shell” or “core” electrons) - 2.8 Valence Electrons

50. How many valence electrons in: 10 Ne 20 Ca 31 Ga Valence Electrons

51. 2.8 Electron Configuration and the Periodic table Review Question: What determined which elements where placed in columns with each other? They all behaved similarly. Let’s use the electron configurations of the alkali metals to see why: 3 Li 1s 2 2s 1 11 Na 1s 2 2s 2 2p 6 3s 1 19 K 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 37 Rb 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 1

52. Valence Electrons Elements with the same number of valence electrons behave similarly to each other. Let’s look for a pattern to quickly determine the number of valence electrons in any MAIN GROUP element. The “one’s place” of the group number of the MAIN GROUPS is the number of valence electrons of the elements in that column.

53. ► ►The periodic table can be divided into four regions or blocks of elements according to the subshells that are last to fill, s, p, d, or f. 2.8 Electron Configuration and the Periodic table

54. Visual method to recall the order of orbital filling.

55. 2.9 Electron-Dot Symbols ► ►Electron-dot symbol: An atomic symbol with dots placed around it to indicate the number of valence electrons.

56. End of Chapter 2

57. Hydrogen has three isotopes: H-1, H-2, and H-3, and has an average atomic mass of 1.00794 amu. Which isotope is most abundant? 1. 1. The three isotopes of hydrogen are equally abundant. 2. 2. H-1 3. 3. H-2 4. 4. H-3

58. Hydrogen has three isotopes: H-1, H-2, and H-3, and has an average atomic mass of 1.00794 amu. Which isotope is most abundant? 1. 1. The three isotopes of hydrogen are equally abundant. 2. 2. H-1 3. 3. H-2 4. 4. H-3

59. The orbitals illustrated below are 1. 1. s orbitals. 2. 2. p orbitals. 3. 3. d orbitals. 4. 4. f orbitals.

60. The orbitals illustrated below are 1. 1. s orbitals. 2. 2. p orbitals. 3. 3. d orbitals. 4. 4. f orbitals.

61. What is the electron configuration of the period 4 group 7A element? 1. 1. 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 5 2. 2. 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 4d 5 3. 3. 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 5 4. 4. 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 4d 10 4p 5

62. What is the electron configuration of the period 4 group 7A element? 1. 1. 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 5 2. 2. 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 4d 5 3. 3. 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 5 4. 4. 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 4d 10 4p 5

63. The number of unpaired electrons contained in an atom of an element in the group indicated in red on the periodic table below is 1. 1. zero. 2. 2. two. 3. 3. four. 4. 4. six.

64. The number of unpaired electrons contained in an atom of an element in the group indicated in red on the periodic table below is 1. 1. zero. 2. 2. two. 3. 3. four. 4. 4. six.

65. The number of valence electrons contained in an atom of the element indicated in blue on the periodic table below is 1. 1. zero. 2. 2. two. 3. 3. four. 4. 4. six.

66. The number of valence electrons contained in an atom of the element indicated in blue on the periodic table below is 1. 1. zero. 2. 2. two. 3. 3. four. 4. 4. six.

67. Elements belonging to the group of elements indicated on the periodic table below are known as the 1. alkali metals. 2. alkaline earth metals. 3. halogens. 4. noble gases.

68. Elements belonging to the group of elements indicated on the periodic table below are known as the 1. alkali metals. 2. alkaline earth metals. 3. halogens. 4. noble gases.

69. What is the outer-shell electron configuration of elements in the group indicated on the periodic table below? 1. ns 2 2. np 2 3. nd 2 4. ns 2 (n–1)d 2

70. What is the outer-shell electron configuration of elements in the group indicated on the periodic table below? 1. ns 2 2. np 2 3. nd 2 4. ns 2 (n–1)d 2

71. The element having chemical properties most similar to As is 1. 1. S 2. 2. Sb 3. 3. Se 4. 4. Si

72. The element having chemical properties most similar to As is 1. 1. S 2. 2. Sb 3. 3. Se 4. 4. Si

73. How many dots are in the electron-dot structure of boron? 1. 1. One 2. 2. Three 3. 3. Five 4. 4. Seven

74. How many dots are in the electron-dot structure of boron? 1. 1. One 2. 2. Three 3. 3. Five 4. 4. Seven

75. How many dots are in the electron-dot structure of the oxide ion, O 2–.? 1. 1. Four 2. 2. Six 3. 3. Eight 4. 4. Ten

76. How many dots are in the electron-dot structure of the oxide ion, O 2–.? 1. 1. Four 2. 2. Six 3. 3. Eight 4. 4. Ten

77. Of the four types of electromagnetic radiation given, which has the most energy? 1. 1. Infrared 2. 2. Microwaves 3. 3. Ultraviolet 4. 4. Visible light

78. Of the four types of electromagnetic radiation given, which has the most energy? 1. 1. Infrared 2. 2. Microwaves 3. 3. Ultraviolet 4. 4. Visible light