1. 1 Chapter 6 Electron structure of atoms

2. 2 6.1 Electromagnetic Radiation Light that we can see is visible light which is a type of electromagnetic radiation. Radiant energy is energy that carries energy that acts like a wave and travels through space at the speed of light. Earth’s Radiant Energy

3. 3 c = speed of light 3.0 x 10 8 m/s

4. 4 Wave characteristics Wavelength: λ, lambda Distance between peaks or troughs in a wave Frequency: ν, nu number of waves, per second that pass a point in one second. Speed: you know this one.

5. 5 Which color has the highest frequency? Lowest frequency? Largest wave length? Smallest wavelength?

6. 6 Electromagnetic Spectrum

7. 7 Flame testing http://www.sciencefriday.com/videos/watch/1 0227 http://www.sciencefriday.com/videos/watch/1 0227

8. 8 Relationship between λ and ν Wavelength and frequency are inverses of each other. λv = c λ = wavelength in meters (m) ν = frequency in cycles per second (1/s or s -1 or Hertz) c = speed of light 3.0 x 10 8 m/s

9. 9 Try one! The red wavelength emitted from red fireworks is around 650 nm and results when strontium salts are heated. Calculate the frequency of the red light of this wavlength. λ v = c λ = (6.50 x 10 2 nm) = 6.50 x 10 -7 m v = 4.61 x10 14 s -1 or Hz

10. 10 6.2 Planck’s Constant Max Planck discovered that energy could be gained or lost in multiples of a constant (h) times its frequency (ν). h = 6.626 x 10 -34 J *s

11. 11 Quantized Energy Thus energy is quantized or in steps or packages. Energy can only be transferred as a whole package or quantum.

12. 12 Solving equations with Planck’s  E = change in energy, in J h = Planck’s constant, 6.626  10  34 J s = frequency, in s  1 = wavelength, in m

13. 13 Calculating energy lost The blue color in fireworks is the result of heated CuCl at 1200 °C. Then the compound emits blue light with a wavelength of 450 nm. What is the increment of energy (quantum) that is emitted at 4.50 x 10 2 nm by CuCl?

14. 14 Answer ΔE = hν v = 3.0 x 10 8 m/s = 6.66 x 10 14 s -1 4.50 x 10 - 7 m v = c/λ (6.626 x 10 -34 J *s) x ( 6.66 x 10 14 s -1 ) = 4.41 x10 -19 J (quantum energy lost in this increment)

15. 15 photons Einstein took Planck’s idea a step further and proposed that electromagnetic radiation was quantized into particles called photons (light). The energy of each photon is given by the expression: E photon = hν = hc/λ

16. 16 Dual Nature of Light Light can behave as if it consists of both waves and particles. Thus light energy has mass

17. 17 Old-ie but good-ie Energy has mass E = mc 2 E = energy m = mass c = speed of light

18. 18 6.4 The Behavior of the wave De Broglie We can calculate the wavelength of an e-. = wavelength, in m h = Planck’s constant, 6.626  10  34 J s v = velocity m = mass in kg

19. 19 Question Compare the wavelength for an electron (mass = 9.11 x10 -31 kg) traveling at a speed of 1.0 x10 7 m/s with that of a ball (mass = 0.10 kg) traveling at 35 m/s

20. 20 Answer Electron wavelength = 7.27 x 10 -11 m ball wavelength = 1.9 x 10 -34 m

21. 21 ν = nu = frequency v = velocity your book uses μ for velocity

22. 22 Homework Chang: pg 303 #’s 1, 2, 7, 9, 15, 20 BL: Pg 230 1, 3, 5, 7, 10, 13, 15,19

23. 23 The relationship between energy and mass ….

24. 24 Light Vocabulary Diffraction: results when light is scattered from a regular array of points or lines

25. 25 Waves = Electrons Planck and Einstein proved that electrons in atoms act like waves of light By understanding waves we can learn about the properties of electrons The study of the properties of electrons is Quantum Mechanics

26. 26 Bohr Model Proposed the first theory on atom location and movement His proposal was a little bit right and a lot wrong…BUT we give him props just the same Nelis Bohr

27. 27 Bohr Model Where he was right… 1. Electrons exist in certain discrete energy levels, which are described by quantum numbers 2. Energy is involved in moving electrons from one energy level to another

28. 28 Heisenberg Uncertainty Principle Blew the Bohr model out of the water. It states that we can only know so much about the exact position and momentum of an electron. …And the electron cloud is born Werner Heisenberger

29. 29 Probability Bohr Model Probability distribution Orbits Electron Cloud Radial probability distribution Orbitals

30. 30 6.5 Quantum model of an atom Compared the relationship between the electron and the nucleus of an atom to that of a standing or stationary wave. The functions of these waves tell us about the electrons location and energy. Erwin SchrÖdinger

31. 31 Schrödinger's Cat He proposed a scenario with a cat in a sealed box, where the cat's life or death was dependent on the state of a subatomic particle. According to Schrödinger, the Copenhagen interpretation implies that the cat remains both alive and dead until the box is opened.

32. 32 We place a living cat into a steel chamber, along with a device containing a vial of hydrocyanic acid. There is, in the chamber, a very small amount of a radioactive substance. If even a single atom of the substance decays during the test period, a relay mechanism will trip a hammer, which will, in turn, break the vial and kill the cat. The observer cannot know whether or not an atom of the substance has decayed, and consequently, cannot know whether the vial has been broken, the hydrocyanic acid released, and the cat killed. Since we cannot know, the cat is both dead and alive according to quantum law, in a superposition of states. It is only when we break open the box and learn the condition of the cat that the superposition is lost, and the cat becomes one or the other (dead or alive). This situation is sometimes called quantum indeterminacy or the observer's paradox: the observation or measurement itself affects an outcome, so that the outcome as such does not exist unless the measurement is made. (That is, there is no single outcome unless it is observed.)quantum superposition

33. 33 Quantum numbers!!!!! Quantum numbers describe various properties of the electrons in an atom. There are 4 quantum numbers Principal quantum number (n) Azimuthual quantum number (angular momentum) (ℓ) Magnetic quantum number (m ℓ ) Electron spin quantum number (m s )

34. 34 Principal quantum number (n) Integral values 1,2,3,4,5,6,7 Related to the size and energy of the orbital Referred to as the shell or energy level

35. 35 Principal quantum number (n) As n increases energy increases and orbital size increases because the electrons are farther away from the nucleus and less tightly bound to the positive protons. n=1 n=4

36. 36 Angular momentum quantum number (ℓ) Integral numbers with values from 0 to n-1 if n = 3 possible ℓ values are 0,1,2 Sometimes referred to as the “sub shell” number Defines the shape of the orbital. ℓ Orbital shape 0s 1p 2d 3f 4g

37. 37 Shape of orbitals ℓ Orbital shape 0s 1p 2d 3f 4g

38. 38 Magnetic quantum number (m ℓ ) Integral values from ℓ to -ℓ including zero If ℓ = 2 Then m ℓ = 2, 1, 0, -1, -2 Relates to the orientation of the orbital in the atom.

39. 39 Electron spin quantum number (m s ) can only have one of two values +1/2 or -1/2 + ½ - ½

40. 40 Re cap A collection of orbitals with the same n value is called an electron shell. EX: all orbitals that have n =3 are in the third shell. A collection of orbitals with the same n and ℓ values are in the same sub shell EX: 2s, 2p

41. 41 Principle Quantum # n # of possible l values Sublevel Shape (ℓ) Orbital number (ℓ)Electron Capacity 10s S11 x 2 = 2e 20, 1s p p33 x 2 = 6e 3 0, 1, 2 s p d d55 x 2 = 10e 4 0, 1, 2, 3 s p d f f77 x 2 = 14e 5 0, 1, 2, 3, 4 s p d f g g99 x 2 = 18e 6 0, 1, 2, 3, 4, 5 s p d f g h h1111 x 2 = 22e 7 0, 1, 2, 3, 4, 5, 6 s p d f g h i i1313 x 2 = 26e Note: In order for the d orbital to be filled the s and p orbitals must be filled. Table 6.2 page 214

42. 42 question For the principle quantum level n = 5 Determine the number of allowed sub shells (ℓ) and give the number and letter designation of each

43. 43 Answer Recall: Angular momentum quantum Integral numbers with values from 0 to n-1 n = 5 ℓ = 0 or s, 1 or p, 2 or d, 3 or f, 4 or g

44. 44 Nomenclature n value ℓ value number of electrons in orbital 2p Y

45. 45 Sorting our the numbers Orbitals with the same n value are in the same shell. Ex: n = 3 is the third shell One or more orbitals with the same set of n and ℓ values are in the same sub shell Ex: n = 3 ℓ= 2 3d sub shell n = 3 ℓ = 1 3p sub shell

46. 46 Homework Chang pg 305 #’s 43, 44. 46, 47, 48, 52, 53,56, 57, 63, BL:Pg 232 41, 43, 45, 46

47. 47 Pauli exclusion principle In a given atom no electrons can have the same 4 quantum number So when we put more than one electron in an orbital we must alternate the spin. Thus m s = +1/2 -1/2

48. 48

49. 49 Example of Pauli Exclusion Principal Quantum numbers for 2s 2 n l m l m s 2s 2 0 0 +1/2 2s 2 0 0 -1/2 When ever possible electrons will prefer to have a positive spin. In this case this orbital will only hold 2 e- so one must be negative

50. 50 Question ? What would the 4 quantum numbers be for 3p 3 ? Note: all electrons have positive spin We will get to why in a minute

51. 51 Answer n l m l m s 3p 31 0 +1/2* 3p 3 1 1 +1/2* 3p 3 1 -1 +1/2*

52. 52 Homework Page 232-33 #’s 52, 53, 54, 56

53. 53 Electron configuration The order in which electrons are distributed to orbitals We need to have rules for how we distribute electrons. Other wise all the electrons would be in the 1s orbital because it has the lowest energy (e- ♥ ground state)

54. 54 Rule 1: Aufbau Principle “building up” Shells fill based on their energy level. Lower energy shells fill first followed by high energy shells. START

55. 55 H: 1s 1 He: 1s 2 Li: 1s 2 2s 1

56. 56 d s p f

57. 57 How to write EC? Li 1s 2s 3 electrons 1s 2 2s 1 Orbital Diagram electron configuration

58. 58 Question ? What is the electron configuration for Carbon?

59. 59 Answer C Carbon has 6 electrons 1s 2 2s 2 2p 2

60. 60 Hund’s Rule: “ the grocery line rule” Electrons are distributed among the orbitals or a sub shell in a way that gives the maximum number of unpaired electrons. C 1s 2 2s 2 2p 2

61. 61 Question Write the orbital diagrams and electron configurations for the electron configurations of each element. Nitrogen Oxygen Fluorine Potassium

62. 62 Answer

63. 63 A note on vocabulary Diamagnetic: all electrons are spin paired Paramagnetic: not all electrons are spin paired

64. 64 Question Of the following elements which are diamagnetic and which are paramagnetic? Boron Oxygen Neon

65. 65 Valence Electrons The electrons in the outermost principle quantum level of an atom. Ve- = to group # Inner electrons are called core electrons. Atom Ve- Location Atom Ve- Location Ca 2 4s N 5 2s 2p Br 7 4p3d

66. 66 Short and Sweet! Writing the EC for Carbon is one thing but Xenon (54e-), Argon (18e-)? To write the condensed EC look to the noble gas BEFORE your element.

67. 67

68. 68 Condensed Form Example Cs = 55 e- Noble gas before it is Xenon Xe= 54e- [Xe] We still need 1 more e- so we write it in [Xe] 6s 1

69. 69 Xe Cs

70. 70 Question? What is the condensed electron configuration for Selenium?

71. 71 Answer Se = 34 e- [Ar] 4s 2 3d 10 4p 4

72. 72 Se Ar

73. 73 EXCEPTION ALERT!!! Memorize the EC of Copper and Chromium. They are exceptions to our rules due to stability Chromium [Ar] 4s 1 3d 5 Copper [Ar] 4s 1 3d 10

74. 74 EXCEPTION ALERT After Lanthanum [Xe]6s 2 5d 1 we start filling 4f

75. 75 EXCEPTION ALERT After Actinium [Rn]7s 2 6d 1 we start filling 5f

76. 76 Homework Pg 233 #’s 59, 60, 61,62, 63, 65