NWTC General Chemistry Ch 10

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  • Figure 10.7 The first four principal energy levels in the hydrogen atom. Each level is assigned a principal quantum number n.
  • Figure 10.13 Atomic structure diagrams of F, Na, and Mg atoms. The number of protons and neutrons is shown in the nucleus. The number of electrons is shown in each principal energy level outside the nucleus.
  • NWTC General Chemistry Ch 10

    1. 1. Chapter 10 Modern Atomic Theory and the Periodic TableThe amazingcolors in thesefireworksexplosions arethe result ofelectronstransferringbetween energy Introduction to General, Organic, and Biochemistry 10elevels in atoms. John Wiley & Sons, Inc Morris Hein, Scott Pattison, and Susan Arena
    2. 2. Chapter Outline10.1 A Brief History 10.5 Atomic Structures of the10.2 Electromagnetic Radiation First 18 Elements10.3 The Bohr Atom 10.6 Electron Structures and the Periodic Table10.4 Energy Levels of Electrons Copyright 2012 John Wiley & Sons, Inc 10-2
    3. 3. Electromagnetic RadiationFrequency tells how many waves pass a particular point per second.Speed tells how fast a wave moves through space.Figure 10.1 The wavelength of this wave is shown by λ. It can be measured from peak to peak or trough to trough. Copyright 2012 John Wiley & Sons, Inc 10-3
    4. 4. The Electromagnetic SpectrumVisible light is only a small part of the electromagnetic spectrum. Copyright 2012 John Wiley & Sons, Inc 10-4
    5. 5. Your Turn!The number of waves that pass a particular point per second is known asa. Frequencyb. Wavelengthc. Amplituded. Speed Copyright 2012 John Wiley & Sons, Inc 10-5
    6. 6. Your Turn!The color of visible light is determined by itsa. Speedb. Wavelengthc. Amplitude Copyright 2012 John Wiley & Sons, Inc 10-6
    7. 7. Bohr Model (1912-1913) Danish physicist Niels Bohr proposed that electrons in an atom are organized into discrete energy levels. He pictured the negative electrons in orbits around the positive nucleus. His evidence: the line spectra of the elements. Copyright 2012 John Wiley & Sons, Inc 10-7
    8. 8. Line SpectrumAtoms absorb energy to give off light..Prisms or diffraction gratings separate the light into a line spectrum for the element. Copyright 2012 John Wiley & Sons, Inc 10-8
    9. 9. Line Spectrum Copyright 2012 John Wiley & Sons, Inc 10-9
    10. 10. *Why so many lines? Absorbed 5 energy 4 3 Released 2 energy Each line in the spectrum corresponds to electrons moving from a higher energy 1 level to a lower energy level. Copyright 2012 John Wiley & Sons, Inc 10-10
    11. 11. Your Turn!Review Question #5: What is meant when we say the electron structure of an atom is in its ground state?a. The highest possible energy level for an electronb. The lowest possible energy level for an electronc. Excited state Copyright 2012 John Wiley & Sons, Inc 10-11
    12. 12. Bohr ModelWas based on electrons having fixed energy levels and therefore quantized amounts of energy.Accounted for spectral lines.Worked very well for hydrogen but did not work well for heavier atoms.Another model is needed that describes the behavior of electrons as waves. Copyright 2012 John Wiley & Sons, Inc 10-12
    13. 13. The Wave-Mechanical Model This mathematical model of the atom describes the energy of the electron with some certainty, but the actual location of the electron is uncertain. An orbital is … the region in space where there is a high probability of finding an Review Questionwith a given energy. electron 1 Copyright 2012 John Wiley & Sons, Inc 10-13
    14. 14. Energy Levels of ElectronsElectrons in atoms are organized into discrete principal energy levels (n, where n is an integer).Lowest energy level is n = 1, then n = 2, etc.As n increases, the energy of the electron increases, and the electron is on average further from the nucleus. Copyright 2012 John Wiley & Sons, Inc 10-14
    15. 15. Sublevels Energy levels are subdivided into sublevels. Each sublevel has orbitals.Review Question 7: What letters are used to designatethe Orbital are designated by types of orbitals? s, p, d and f. n = 1 has the sublevel 1s. n = 2 has the sublevels 2s and 2p. Each sublevel is made up of orbitals of the same type and energy. 10-15
    16. 16. Electron SpinReview Question 2: What conditions allow a 2nd electron to enter an orbital Each electron in an atom appears to be spinning on its axis. Pauli exclusion principle states that an atomic orbital can hold a maximum of two electrons, which must have opposite spin. What is the maximum number of electrons in any orbital? 2 Copyright 2012 John Wiley & Sons, Inc 10-16
    17. 17. s SublevelsReview Question 6: How do 1s and 2s differ? Every principal energy level has an s sublevel that contains a single s orbital which is farther away. (1s, 2s, 3s, etc.) There is a 90% probability of finding the electron within a spherical region surrounding the nucleus.Review Question 6: How are 1s and 2s alike? Each s orbital is the same shape and holds 2 electrons with opposite spin. Copyright 2012 John Wiley & Sons, Inc 10-17
    18. 18. p SublevelsEvery principal energy level starting at n = 2 has a p sublevel (2p, 3p, etc.) that contains 3 equal energy p orbitals. The orbitals only differ by their orientation in 3-D space. Copyright 2012 John Wiley & Sons, Inc 10-18
    19. 19. Your Turn!What is the maximum number of electrons in a 2p orbital?a. 2 A 2p sublevel holds 6 electrons, 2b. 4 electrons per orbital.c. 6 The maximum number of electrons ind. 8 ANY orbital is 2. Copyright 2012 John Wiley & Sons, Inc 10-19
    20. 20. d SublevelsEvery principal energy level starting at n = 3 has a d sublevel (3d, 4d, etc.) that contains 5 equal energy d orbitals. These orbitals have more complex shapes and are higher in energy than the s and p orbitals. Copyright 2012 John Wiley & Sons, Inc 10-20
    21. 21. Your Turn!What is the maximum number of electrons in a 3d sublevel?a. 2 A 3d sublevel has 5 orbitals, so it holdsb. 4 10 electrons, 2 electrons per orbital.c. 6d. 10 Copyright 2012 John Wiley & Sons, Inc 10-21
    22. 22. SummaryEach subshell is composed of orbitalsThe number of orbitals depends on the subshell2 electrons per orbitalSublevel s p d fNumber of Orbitals 1 3 5 7Electrons 2 6 10 14 Review Question 9Shape sphere fig. 8 lobes hard to visualizeReview Question 10: Difference between orbital & Sons, Inc orbit? Copyright 2012 John Wiley and Bohr 10-22
    23. 23. Rules for Distributing Electrons1. No more than two electrons can occupy one orbital.2. Electrons occupy the lowest energy orbitals available. s < p < d < f for a given value of n3. Each orbital in a sublevel is occupied by a single electron before a second electron enters. (Hunds Rule) Copyright 2012 John Wiley & Sons, Inc 10-23
    24. 24. Your Turn!In the fourth principal energy level, which sublevel contains electrons with the greatest energy?a. 4sb. 4pc. 4dd. 4f Copyright 2012 John Wiley & Sons, Inc 10-24
    25. 25. Your Turn!How many orbitals are found in a 5p sublevel?a. 1 The number of orbitals found in ANYb. 3 energy level is 3.c. 5d. 7 Copyright 2012 John Wiley & Sons, Inc 10-25
    26. 26. Your Turn!What is the maximum number of electrons that can occupy the third principal energy level?a. 2 3s = 2b. 6 3p = 6c. 8 3d = 10d. 18 2+6+10 = 18 Copyright 2012 John Wiley & Sons, Inc 10-26
    27. 27. Atomic StructureOne way to indicate atomic structure shows the structure of the nucleus and the number of electrons in each energy level.Review Question 8: List in order of increasing energy?2s 2p 4s 1s 3d 4p 3s1s 2s 2p 3s 3p 3d 4s 4p Copyright 2012 John Wiley & Sons, Inc 10-27
    28. 28. Electron Configuration Another useful atomic structure shows the distribution of electrons in the atom. 4 is the energy level, f is the orbital in the sublevel and 3 is the number of electronsReview Question 13: An element has the designation 4f 3.What is the significance of the 2012 f & 3?& Sons, Inc Copyright 4, John Wiley 10-28
    29. 29. Orbital DiagramElectron configurations can also be shown with orbital diagrams. Each box represents an orbital.Up and down arrows represent electrons of opposite spin. Copyright 2012 John Wiley & Sons, Inc 10-29
    30. 30. Atomic Structureorbital3Li 1s22s1 4Be 1s22s2 1s 2s 1s 2s5B 1s22s22p1 1s 2s 2p sublevel6C 1s22s22p2 1s 2s 2p7N 1s22s22p2 1s 2s 2p8O 1s22s22p2 1s 2s 2pEnergy level Copyright 2012 John Wiley & Sons, Inc 10-30
    31. 31. Atomic Structure Copyright 2012 John Wiley & Sons, Inc 10-31
    32. 32. Atomic StructureRemember to sum the superscripts in the electron configuration.They should add up to the atomic number for the element. Copyright 2012 John Wiley & Sons, Inc 10-32
    33. 33. Valence ElectronsThe valence electrons …include all of the electrons in the highest principal quantum number (the outermost energy level).These electrons are the electrons that are involved in bonding. Review Question 4Phosphorus: 1s2 2s2 2p6 3s2 3p3Phosphorus has 5 valence electrons. Copyright 2012 John Wiley & Sons, Inc 10-33
    34. 34. Your Turn!Atoms of which element have the following electron configuration? 1s2 2s2 2p6 3s23p6a. Clb. Cac. Ard. S Copyright 2012 John Wiley & Sons, Inc 10-34
    35. 35. The Periodic Table Each horizontal row in the periodic table is called a period. The number of each period corresponds to the outermost energy level of the element. For example, Ar is in period 3 and its outermost energy level is 3. 1s2 2s2 2p6 3s23p6 Argon has 8 electrons in energy level 3. Eight is the most of any period.Review Question 18: What is Copyright 2012 Johnnumber ofInc the greatest Wiley & Sons, electrons in a period? 10-35
    36. 36. The Periodic Table Groups or Families (a column) contain elements whose properties are similar. Representative Elements – A Groups • Alkali Metals –1A • Alkaline Earth Metals – 2A • Halogens – 7A • Noble Gases – 8A O, S &SeReview Question 17: Write the symbols of the first 3 elements with 6 electrons in their Copyright 2012 John Wiley & Sons, Inc 10-36outermost energy level?
    37. 37. Other Groups to Know Transition Metals – B Groups Inner Transition Metals – Lanthanides (Rare Earth) – Atomic Nos. 58 -71 – Actinides – Atomic Nos. 90 – 103 Last electron in Group A goes into p sublevel. Last electron in Group B goes into d sublevel.Review Question 19: How does the placement of the last electron in Group A differ Copyright 2012 John Wiley & Sons, Inc 10-37from Group B elements?
    38. 38. Your Turn!Which element is a transition element?a. sodiumb. fluorinec. copperd. lead Copyright 2012 John Wiley & Sons, Inc 10-38
    39. 39. Your Turn!Chlorine is a member of what family of elements?a. Noble gasesb. Alkali metalsc. Halogensd. Chalcogens Copyright 2012 John Wiley & Sons, Inc 10-39
    40. 40. Valence Electrons and GroupsIn the following groups, the group number is the numberof valence electrons.Elements within a group have the same valence electronconfiguration. Copyright 2012 John Wiley & Sons, Inc 10-40
    41. 41. Your Turn!In which category of the periodic table does each element contain valence electrons in the second principal energy level?a. The alkaline earth elementsb. The alkali metalsc. Group 2Ad. Period 2 Copyright 2012 John Wiley & Sons, Inc 10-41
    42. 42. Your Turn!On the periodic table, elements in the same group contain the same number ofa. Protonsb. Electronsc. Principal energy levels in their ground stated. Valence electrons in their ground state Copyright 2012 John Wiley & Sons, Inc 10-42
    43. 43. Electron Configurations and the Periodic Table Copyright 2012 John Wiley & Sons, Inc 10-43
    44. 44. Electron Configurations and the Periodic Table 1. The number of the period corresponds with the highest occupied energy level. 2. The group numbers for the representative elements are equal to the total number of valence electrons. 3. The elements within a group have the same number of valence electrons. 4. The elements within each of the s, p, d, f blocks are filling s, p, d, f orbitals. 5. There are discrepancies within the transition elements.Review Question 20: Where on the periodic table are elements not in the proper sequence Copyright 2012 John Wiley & Sons, Inc 10-44according to atomic mass.
    45. 45. Abbreviated Electron ConfigurationsUse the symbol of the nearest preceding noble gas to represent the electron configuration of the core electrons.Phosphorus: 1s2 2s2 2p6 3s2 3p3 Core Valence Electrons [Ne] 3s2 3p3 Electrons Copyright 2012 John Wiley & Sons, Inc 10-45
    46. 46. Your Turn!The electron configuration, [Ar] 4s1, is the ground state electron configuration ofa. Potassiumb. Phosphorousc. Fluorined. Sodium Copyright 2012 John Wiley & Sons, Inc 10-46
    47. 47. Your Turn!The electron configuration, [Ne] 3s2 3p1, is the ground state electron configuration ofa. Sodiumb. Aluminumc. Argond. Sulfur Copyright 2012 John Wiley & Sons, Inc 10-47
    48. 48. QuestionsReview Questions – Did in classPaired Questions (pg 210) – Do 1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45, 49 – Practice later every other even (2, 6, etc) Copyright 2012 John Wiley & Sons, Inc 1-48

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