Structure 1.3 - Electron configurations.pptx

chem

1. Structure 1.3 Electron configurations Guiding question: How can we model the energy states of electrons in atoms? Time : SL and HL - 3 h AHL - 3 h 1

2. Prior knowledge Which types of electromagnetic radiation are relevant in these contexts? What is different about different types of electromagnetic radiation? 2

3. SL and HL content 3

4. Part A The electromagnetic spectrum 4

5. What is the relationship between wavelength and the energy of electromagnetic radiation? 5

6. What is electromagnetic radiation? Radiation that has both electric and magnetic fields can be modelled as both: 6

7. Properties of electromagnetic radiation : Wavelength 7

8. Properties of electromagnetic radiation : Frequency 8

9. How are wavelength, frequency and energy related? c = 𝜆 𝜈 E = h 𝜈 9

10. Quick check : The visible region of electromagnetic radiation What are the different colours of light in the visible region of the electromagnetic spectrum? Which colour of visible light has: the longest wavelength? the highest frequency? the greatest energy? 10

11. Practice questions Identify the region of the electromagnetic spectrum that has: Shortest wavelength Lowest frequency Lowest energy 11

12. Part B Emission spectra and the Bohr model of the atom 12

13. What is white light? Where might we find it? Can you explain what is happening in the image above? 13

14. Practical : Continuous and line emission spectra A diffraction grating separates the different components of electromagnetic radiation. With our eyes, we will be see any colours present in the visible region. Record your observations when: Looking at white light Looking at a hydrogen gas lamp What differences do you notice? 14

15. Continuous and line emission spectra 15

16. The Bohr model : What causes the release of specific frequencies of energy? 16

17. The Bohr model and the hydrogen emission spectrum 17

18. An energy level diagram for the hydrogen emission spectrum 18

19. Hydrogen emission spectrum : Drops to n=1 and n=3 seen in the visible region of the EM spectrum 19

20. Quick check (MCQ) What do the lines on the hydrogen emission spectrum represent? The energy levels in a hydrogen atom The energy gap between energy levels in a hydrogen atom Excited electrons in hydrogen atoms Relaxed electrons in hydrogen atoms The hydrogen emission spectrum is caused by electrons dropping to which energy level? Why do the lines on an emission spectrum converge at higher energies? 20

21. Practical : Flame tests Hold wooden splints soaked in different metal ion solutions in a Bunsen burner flame. Record your observations. Identify the likely metal ion present in the two unknown solutions. 21

22. Hydrogen emission spectrum : Excitation to n=∞ 22

23. Practice questions Sketch an energy level diagram with 6 energy levels. Add and label arrows showing an electron transition… Caused by the absorption of energy. Representing a line in the hydrogen emission spectrum. That would represent the largest possible energy emission. 2. Explain why we do not see lines on a hydrogen emission spectrum caused by drops to n=1. 23

24. Part C Energy levels, sublevels and orbitals 24

25. Can you identify a mathematical formula that relates the energy level (n) and its maximum number of electrons? Predict the maximum number of electrons held in the n=4 energy level. Energy level Maximum number of electrons n=1 2 n=2 8 n=3 18 n=4 ? 25

26. Main energy levels Energy level Maximum number of electrons n=1 n=2 n=3 n=4 26 2 8 18 32

27. Main energy levels → sublevels Main energy level Number of sublevels Which sublevels are used? n=1 s n=2 s, p n=3 3 s, p, d n=4 4 s, p, d, f 27 1 2

28. Sublevel Number of orbitals in sublevel Shapes of orbitals s 1 p 3 px , pppppp d 5 f 7 Sublevels → orbitals 28

29. Summary Main energy level Sublevels Total number of orbitals Maximum no. electrons n=1 s 1 2 n=2 p 3 6 n=3 d 5 10 n=4 f 7 14 29

30. Practice questions State the sublevels found in the n=1, n=2, n=3 and n=4 main energy levels. Define ‘orbital’. The area where you have high probability of finding electron State the number of electrons found in a single orbital. 2 Sketch the shape of an s orbital. Sketch a p z orbital on these axes → State the number of orbitals are found in the s, p, d and f sublevels. 1, 3, 5, 7 Explain, in terms of sublevels and orbitals, why the n=4 energy level can contain a maximum of 32 electrons. It has 4s, 4p, 4d, and 4f sublevels, the s orbital has 1 orbital, p 3, d 5, f 7. and one orbital contains 2 electron. We have 16 orbital in total, so there are 32 electrons 30

31. Part D Electron configurations 31

32. Which of these orbitals might you be expected to sketch in IB Chemistry? 32

33. How do we represent orbitals more simply? 33

34. Orbital box diagram for n=1, n=2 and n=3 energy levels 34 Reminder: Main energy level Sublevels Total number of orbitals n=1 s 1 n=2 s, p 1 + 3 n=3 s, p, d 1 + 3 + 5

35. Orbital box diagrams How might we draw the first 8 electrons in an atom? 35

36. 1s 2s 2p 3s 3d 3p 4s 4p Electrons fill the lowest available energy level 4s fills before 3d Electrons remain unpaired as far as possible Cr an electron is promoted from 4s to 3d to give a half-filled 3d subshell Cu an electron is promoted from 4s to 3d to give a full 3d subshell Click to add electrons 36

37. 1s 2s 2p 3s 3d 3p 4s 4p Electronic configuration in shorthand nomenclature Click to add electrons H 1s 1 He 1s 2 Li 1s 2 2s 1 Be 1s 2 2s 2 B 1s 2 2s 2 2p 1 C 1s 2 2s 2 2p 2 N 1s 2 2s 2 2p 3 O 1s 2 2s 2 2p 4 F 1s 2 2s 2 2p 5 Ne 1s 2 2s 2 2p 6 Na 1s 2 2s 2 2p 6 3s 1 Mg 1s 2 2s 2 2p 6 3s 2 Al 1s 2 2s 2 2p 6 3s 2 3p 1 Si 1s 2 2s 2 2p 6 3s 2 3p 2 P 1s 2 2s 2 2p 6 3s 2 3p 3 S 1s 2 2s 2 2p 6 3s 2 3p 4 Cl 1s 2 2s 2 2p 6 3s 2 3p 5 Ar 1s 2 2s 2 2p 6 3s 2 3p 6 K 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 Ca 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 Sc 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 1 Ti 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 2 V 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 3 Cr 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 3d 5 Mn 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 5 Fe 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 6 Co 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 7 Ni 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 8 Cu 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 3d 10 Zn 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 Ga 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 1 Ge 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 2 As 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 3 Se 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 4 Br 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 5 Kr 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 37

38. Quick check Symbol Full e - configuration Condensed e - configuration Li C Cu Fe Cr 38

39. How do we write e - configurations for ions? Atom Full e - configuration of atom Ion Full e - configuration of ion Li Li + O O 2- Mg Mg 2+ Fe Fe 3+ Cu Cu 2+ 39

40. Using the periodic table to write e - configurations 40

41. Practice Symbol Full e - configuration Condensed e - configuration Be N Si Cu Ti 4+ Mn 2+ Cu + Se 2- 41

42. AHL content 42

43. Part E First ionization energy 43

44. In what sense are the outer electrons in an atom ‘shielded’ by inner electrons? 44

45. What is ‘first ionization energy’? Definition: General formula: 45

46. Data for 1st ionization energy across a period 46

47. Quick check 47

48. How does 1st ionization energy change down a group? Predict the general trend in 1st ionization energies down a group. 48

49. Practice questions Predict and explain the general trend in 1st ionization energy down group 2. Explain the general trend in 1st ionization energy across a period. Explain the discontinuities (exceptions) to the general trend in the 1st ionization energies of period 3 elements → 49

50. Part F Successive ionization energies 50

51. 1st ionization energy: X (g) → X + (g) + e - Write a general equation for the 2nd and 3rd ionization energy. 51

52. Successive ionization energies of Na 52

53. Quick check Sketch the successive ionization energies for a nitrogen atom. 53

54. Practice question 54

55. Part G The limit of convergence and ionization 55

56. E = h 𝜈 h = 6.63 x 10 -34 J s A radio station transmits at a frequency of 1.089 x 10 6 s -1 . Use the data provided to calculate the energy of the photon of the transmission waves in kJ. 56

57. The limit of convergence 57

58. How do we calculate ionization energy from spectral data? The convergence limit for a hydrogen atom occurs at a frequency of 3.28 x 10 15 Hz. Calculate the: First ionization energy for a hydrogen atom in J. First ionization energy for a hydrogen atom in kJ. First ionization energy for hydrogen in kJ mol -1 . Data booklet : E = h 𝜈 h = 6.63 x 10 -34 J s 1 mol = 6.02 x 10 23 particles c = 𝜈 𝜆 c = 3.00 x 10 8 m s -1 58

59. Practice question A beam of electromagnetic radiation has an energy of 3.65 x 10 -20 J per photon. Calculate the frequency of the radiation. Calculate the wavelength of the radiation. Identify the type of electromagnetic radiation using the electromagnetic spectrum below. 59

60. Practice question 2. The electron in a hydrogen atom reaches the convergence limit when it absorbs radiation with a wavelength of 9.15 x 10 -8 m. Calculate the ionisation energy in kJ mol -1 . 60

61. Guiding question and review 61

62. How can we model the energy states of electrons in atoms? 62 Where do we find electrons? How do we represent the position of electrons? How do electrons change energy states? AHL - How can we ionize an atom?

63. Key terminology Wavelength Frequency Continuous spectrum Line spectrum Photon Hydrogen emission spectrum Orbital AHL: Ionization energy 63

64. Past-paper questions 64

65. Retrieval practice 65

66. Gamma rays Infrared Microwaves Visible light X-rays Radio waves Ultraviolet Retrieval practice : Place the following regions of the electromagnetic spectrum in order of increasing frequency. 66

67. Nature of science : Which elements might be found in the unknown star? How do emission spectra provide evidence for the existence of different elements? Unknown star 67

68. Retrieval practice : Complete this table. Main energy level Sublevels Total number of orbitals Maximum no. electrons n=1 n=2 n=3 n=4 68

69. Has the e - configuration 1s 2 2s 2 2p 6 3s 2 . Has 2 electrons in the second energy level. Has the e - configuration 1s 2 . Contains [Ar] in its condensed e - configuration. Finishes with p 2 in its e configuration. Contains an unpaired electron in an s-orbital. Contains a half filled set of d-orbitals. Contains a complete p sub-level. Has 28e - in its 2+ ion. Retrieval practice : State the name of an element that... 69

70. Inner electrons shield valence electrons from the positive charge in the nucleus. Elements in the same group have the same number of shielding electrons. Elements in the same period have the same number of shielding electrons. Down a group, 1st ionization energy increases as valence electrons are found further from the nucleus. Across a period, the general trend in 1st ionization energy in increasing. Retrieval practice : True or false? 70

71. The first four successive ionization energies are: 420, 3600, 4400 and 5900 kJ mol -1 Which group of the periodic would this element be found? 71

72. NOS and TOK 72

73. NOS/TOK : Evidence, models and theories Use examples from Structure 1.3 to explain the relationship between these: Can you do the same using examples from another IB subject? Evidence Models Theories 73

74. NOS : Logarithmic scales Why do we often use logarithmic scales in science? 74

75. Extension 75

76. Extension : Doppler shift How can emission and absorption spectra tell us about movement? 76

77. Extension : Atomic absorption spectra What are the difference between an emission line spectrum and an absorption line spectrum? What causes these differences? 77

78. Extension : Electron configurations and quantum numbers 78