1. Chemical Ideas 6.7 Where does colour come from?

2. 25 questions to see what you’ve remembered.

3. More about the colour we see.. Key stage 3 stuff.

4. 1. What colour is the light reaching my eye? Explain. Red filter transmit absorb reflect

5. 2. What colour is the light reaching my eye? Explain. Blue filter transmit absorb reflect

6. 3. What colour is the light reaching my eye? Explain. Colourless glass transmit absorb reflect

7. 4. What colour does the ball look? Explain. transmit absorb reflect

8. 5. What colour does the ball look? Explain. transmit absorb reflect

9. 6. What colour does the ball look? Explain. transmit absorb reflect

10. 7. What colour does the ball look? Explain transmit absorb reflect

11. 8. What colour does the ball look? Explain. transmit absorb reflect

12. 9. The rays are … A. Refracted B. Reflected C. Dispersed D. Converged

13. 10. Name the 3 primary colours of light …

14. Chemical Ideas 6.1 Light and the electron.

15. Sometimes we use the wave model for light … λ (lambda)= wavelength

16. 11. Wavelength increases, Frequency ? C

17. 12. Sketch the e.m.s. and use arrows to mark: Increasing energy Increasing wavelength Increasing frequency

18. C = λν problems…. Work out v: 13. If λ is 3.00 m 14 If λ is 30.0 cm 15. If λ is 3.00 mm Work out λ: 16. If ν is 3.00 x 10 10 Hz c = 3.00x10 8 m s -1

19. Sometimes we use the particle model … Packages of energy are called photons Light is a stream of photons E = 6.63 x10 -34 x 4.5 x 10 14 = 3.0 x 10 -19 J Hz h = 6.63 x 10 -34 J Hz -1 Planck constant

20. E = hν problems … h = 6.63 x 10-34 J Hz -1 Planck constant 17. If the frequency is 1.089 x 10 6 Hz, what is the energy of each photon? 18. If E = 3.65 x 10 -20 J per photon, what is the frequency (ν) of the radiation?

21. 19. Absorption or emission Spectrum of hydrogen? Black background Coloured lines.

22. Spectroscopy Sample of hydrogen High voltage Prism

23. Electrons can only exist in fixed energy levels. ΔEΔE Electrons absorb energy and move to a higher energy level. The electrons drop back to a lower energy level and emit energy. The frequency of the radiation emitted depends on ΔE.

24. 20. Red? 21. Blue/green? ?

25. 5 7 etc 1 2 3 4 6 22. Why no 7  2 8  2 9  2?

26. 23. What happens to electrons? 1 2 3 4

27. Chemical Ideas 6.2 What happens when radiation interacts with matter?

28. Molecules are made of more than one atom but they still have electrons. Electronic transitions Vis + UV

29. 24. Molecules move ! How?

30. 25.There are vibrational energy levels as well as electronic energy level. ΔE in which region?

31. The answers …

32. 1. What colour is the light reaching my eye? Explain. Red filter Red

33. 2. What colour is the light reaching my eye? Explain. Blue filter Blue

34. 3. What colour is the light reaching my eye? Explain. Colourless glass White

35. 4. What colour does the ball look? Explain. Red

36. 5. What colour does the ball look? Explain. Black

37. 6. What colour does the ball look? Explain. White

38. 7.What colour does the ball look? Explain. Red

39. 8. What colour does the ball look? Explain. Black

40. 9. The rays are … A. Refracted B. Reflected C. Dispersed D. Converged

41. 10. Name the 3 primary colours of light …

42. Sometimes we use the wave model for light … λ (lambda)= wavelength

43. 11. Wavelength increases, Frequency ? C decreases

44. energy wavelength frequency 12.

45. c = λ ν c νλ c = speed of light = 3.00 x 10 8 m s -1 λ = wavelength m lambda ν = frequency Hz ( or s -1 ) nu Use m for λ

46. C = λν problems…. Work out v: 13. If λ is 3.00 m 14. If λ is 30.0 cm 15. If λ is 3.00 mm Work out λ: 16. If ν is 3.00 x 10 10 Hz c = 3.00x10 8 m s -1

47. Sometimes we use the particle model … Packages of energy are called photons Light is a stream of photons E = 6.63 x10 -34 x 4.5 x 10 14 = 3.0 x 10 -19 J Hz h = 6.63 x 10 -34 J Hz -1 Planck constant

48. Rearranging again…. E h

49. E = hν problems … h = 6.63 x 10-34 J Hz -1 Planck constant 17. If the frequency is 1.089 x 10 6 Hz, what is the energy of each photon? 18. If E = 3.65 x 10 -20 J per photon, what is the frequency (ν) of the radiation?

50. 19. Black background Coloured lines. emission

51. Spectroscopy Sample of hydrogen High voltage Prism

52. Electrons can only exist in fixed energy levels. ΔEΔE Electrons absorb energy and move to a higher energy level. The electrons drop back to a lower energy level and emit energy. The frequency of the radiation emitted depends on ΔE.

53. 20. 3  2 21. 4  2 ?

54. 5 7 etc 1 2 3 4 6 22. Why no 7  2 8  2 9  2?

55. visibleultra violet E increases

56. 6 1 2 3 4 Balmer  2 E increasing Lyman  ? 1 2 3 4 1

58. Absorption Spectrum of hydrogen. Continuous spectrum Black lines.

59. How do the 2 compare?

60. 23.What happens to electrons? 1 2 3 4 Electrons absorb energy Electrons are excited Electrons move to higher energy level E = h v

61. Molecules are made of more than one atom but they still have electrons. Electronic transitions Vis + UV

62. 24. Molecules move ! How?

63. 25. There are vibrational energy levels as well as electronic energy level.. I.R.

64. Electronic transitions Vis + UV Rotational transitions Vibrational transitions Microwave I.R.

65. Chemical Ideas 6.7 Where does colour come from?

66. Absorb Transmits Complementary

67. Absorb Transmits Complementary

68. Absorb Transmits Complementary

69. X2X2 X2*X2*

74. e-e- e-e- filter meter photocell cuvette

75. concentration absorbance Absorbance α concentration