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Chemical Ideas 6.7

Chemical Ideas 6.7. Where does colour come from?. 25 questions to see what you’ve remembered. More about the colour we see .. Key stage 3 stuff. 1. What colour is the light reaching my eye? Explain. Red filter. transmit absorb reflect.

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Chemical Ideas 6.7

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

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

  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 6.1Light 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 = 3.00x108 m s-1 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 1010 Hz

  19. Sometimes we use the particle model … Hz h = 6.63 x 10-34 J Hz -1 Planck constant • Packages of energy are called photons • Light is a stream of photons • E = 6.63 x10-34 x 4.5 x 1014 = 3.0 x 10-19 J

  20. E = hν problems … • h = 6.63 x 10-34 J Hz -1 • Planck constant 17. If the frequency is 1.089 x 106 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. • Electrons absorb energy and move to a higher energy level. ΔE • 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. 22. Why no • 7  2 • 8  2 • 9  2? 1 2 3 4 6 7 etc 5

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

  27. Chemical Ideas 6.2What 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 ? decreases C

  44. 12. energy wavelength frequency

  45. c = λν λ = wavelength m lambda c = speed of light = 3.00 x 108 m s-1 ν = frequency Hz ( or s-1 ) nu Use m for λ c λ ν

  46. c = 3.00x108 m s-1 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 1010 Hz

  47. Sometimes we use the particle model … Hz h = 6.63 x 10-34 J Hz -1 Planck constant • Packages of energy are called photons • Light is a stream of photons • E = 6.63 x10-34 x 4.5 x 1014 = 3.0 x 10-19 J

  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 106 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. emission • Black background • Coloured lines.

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