1.Tutorial on Electromagnetic Radiation, Emission Line spectrum and Bohr Model.Prepared by Lawrence Kok http://lawrencekok.blogspot.com

2. Electromagnetic Spectrum Electromagnetic spectrum ranges from Radiowaves to Gamma waves. - Form of energy - Shorter wavelength -> Higher frequency -> Higher energy - Longer wavelength -> Lower frequency -> Lower energy 3. Electromagnetic Spectrum Electromagnetic spectrum ranges from Radiowaves to Gamma waves. - Form of energy - Shorter wavelength -> Higher frequency -> Higher energy - Longer wavelength -> Lower frequency -> Lower energyWavelength, - long Frequency, f- low Wavelength, - short Inverse relationship between- and fFrequency, f- high 4. Electromagnetic Spectrum Electromagnetic spectrum ranges from Radiowaves to Gamma waves. - Form of energy - Shorter wavelength -> Higher frequency -> Higher energy - Longer wavelength -> Lower frequency -> Lower energyWavelength, - long Frequency, f- low Wavelength, - short Inverse relationship between- and fFrequency, f- high Electromagnetic radiation Travel at speed of light, c = f -> 3.0 x 108 m/s Light Particle photon have energy given by -> E = hf Energy photon - proportional to frequencyPlank constant proportionality constant bet energy and freqExcellent video wave propagation Click here to view. 5. Electromagnetic Wave propagation. Electromagnetic radiation Moving charges/particles through space Oscillating wave like property of electric and magnetic field Electric and magnetic field oscillate perpendicular to each other and perpendicular to direction of wave propagation.Electromagnetic radiation Electromagnetic wave propagationClick here to view video 6. Electromagnetic Wave propagation. Electromagnetic radiation Moving charges/particles through space Oscillating wave like property of electric and magnetic field Electric and magnetic field oscillate perpendicular to each other and perpendicular to direction of wave propagation.Electromagnetic radiation Electromagnetic wave propagationClick here to view videoWaveWave wavelength and frequency - travel at speed of light 7. Electromagnetic Wave propagation. Electromagnetic radiation Moving charges/particles through space Oscillating wave like property of electric and magnetic field Electric and magnetic field oscillate perpendicular to each other and perpendicular to direction of wave propagation.Electromagnetic radiation Electromagnetic wave propagationClick here to view videoViolet = 410nm f = c/ = 3 x 108/410 x 10-9 = 7.31 x 1014 Hz E = hf = 6.626 x 10-34 x 7.31 x 1014 = 4.84 x 10-19 JWaveWave wavelength and frequency - travel at speed of lightRed = 700nm f = c/ = 3 x 108/700 x 10-9 = 4.28 x 1014 Hz E = hf = 6.626 x 10-34 x 4.28 x 1014 = 2.83 x 10-19 J 8. Electromagnetic Wave propagation. Electromagnetic radiation Moving charges/particles through space Oscillating wave like property of electric and magnetic field Electric and magnetic field oscillate perpendicular to each other and perpendicular to direction of wave propagation. Electromagnetic radiation Is it a particle or Wave?Click to view video -Wave-particle dualityWaveWave wavelength and frequency - travel at speed of light 9. Electromagnetic Wave propagation. Electromagnetic radiation Moving charges/particles through space Oscillating wave like property of electric and magnetic field Electric and magnetic field oscillate perpendicular to each other and perpendicular to direction of wave propagation. Electromagnetic radiation Is it a particle or Wave?Click to view video -Wave-particle dualityWaveWave wavelength and frequency - travel at speed of lightSimulation on Electromagnetic PropagationClick here to view simulationClick here to view simulationClick here to view simulation 10. Electromagnetic Wave VioletRed = 410nm = 700nmf = c/ = 3 x 108/410 x 10-9 = 7.31 x 1014 Hzf = c/ = 3 x 108/700 x 10-9 = 4.28 x 1014 HzWavelength Distance bet two point with same phase, bet crest/troughs unit nm Frequency Number of cycle/repeat per unit time (cycles in 1 second) unit Hz 11. Electromagnetic Wave VioletRed = 410nm = 700nmf = c/ = 3 x 108/410 x 10-9 = 7.31 x 1014 Hzf = c/ = 3 x 108/700 x 10-9 = 4.28 x 1014 HzWavelength Distance bet two point with same phase, bet crest/troughs unit nm Frequency Number of cycle/repeat per unit time (cycles in 1 second) unit HzWhich wave have higher frequency, if both have same speed reaching Y same time? VioletXYRed 12. Electromagnetic Wave VioletRed = 410nm = 700nmf = c/ = 3 x 108/410 x 10-9 = 7.31 x 1014 Hzf = c/ = 3 x 108/700 x 10-9 = 4.28 x 1014 HzWavelength Distance bet two point with same phase, bet crest/troughs unit nm Frequency Number of cycle/repeat per unit time (cycles in 1 second) unit HzWhich wave have higher frequency, if both have same speed reaching Y same time? VioletXClick here on excellent video red /violet waveClick here to view video energy photonY Light travel same speed Red flippers long - less frequent Violet shoes short - more frequentRed 13. Continuous Spectrum Vs Line SpectrumContinuous Spectrum : Light spectrum with all wavelength/frequency Emission Line Spectrum : Spectrum with discrete wavelength/ frequency Emitted when excited electrons drop from higher to lower energy level Absorption Line Spectrum : Spectrum with discrete wavelength/frequency Absorbed when ground state electrons are excited 14. Continuous Spectrum Vs Line SpectrumContinuous Spectrum : Light spectrum with all wavelength/frequency Emission Line Spectrum : Spectrum with discrete wavelength/ frequency Emitted when excited electrons drop from higher to lower energy level Absorption Line Spectrum : Spectrum with discrete wavelength/frequency Absorbed when ground state electrons are excited Atomic Emission Electrons from excited stateExcited stateEmit radiation when drop to ground stateRadiation emittedEmission SpectrumGround statehttp://www.astrophys-assist.com/educate/orion/orion02.htm 15. Continuous Spectrum Vs Line SpectrumContinuous Spectrum : Light spectrum with all wavelength/frequency Emission Line Spectrum : Spectrum with discrete wavelength/ frequency Emitted when excited electrons drop from higher to lower energy level Absorption Line Spectrum : Spectrum with discrete wavelength/frequency Absorbed when ground state electrons are excited Atomic Emission Vs Atomic Absorption Spectroscopy Electrons from excited stateExcited stateElectrons in excited stateEmit radiation when drop to ground stateRadiation absorbed Radiation emitted Absorb radiation to excited stateEmission SpectrumGround statehttp://www.astrophys-assist.com/educate/orion/orion02.htmElectrons from ground state 16. Line Emission Spectroscopy Line Emission Spectra for Hydrogen Energy supplied to atoms Electrons excited - ground to excited states Electrons exist fixed energy level (quantum) Electrons transition from higher to lower, emit energy of particular wavelength/frequency - photon Higher the energy level, smaller the difference in energy bet successive energy level. Spectrum converge (get closer) with increase freq. Lines spectrum converge- energy levels also converge Ionisation energy determined (Limit of convergence)UV region Lyman Series n= n= 1Visible region Balmer Series n= n= 2IR region Paschen Series n= n= 3 17. Line Emission Spectroscopy Line Emission Spectra for Hydrogen Energy supplied to atoms Electrons excited - ground to excited states Electrons exist fixed energy level (quantum) Electrons transition from higher to lower, emit energy of particular wavelength/frequency - photon Higher the energy level, smaller the difference in energy bet successive energy level. Spectrum converge (get closer) with increase freq. Lines spectrum converge- energy levels also converge Ionisation energy determined (Limit of convergence)UV region Lyman Series n= n= 1Visible region Balmer Series n= n= 2IR region Paschen Series n= n= 3Line Emission Spectra Energy supplied Electrons surround nucleus in allowed energy states (quantum) Excited electron return to lower energy level, photon with discrete energy/wavelength (colour) given out. Light pass through spectroscope (prism/diffraction grating) to separate out diff coloursN= 6-2 410nmN= 5-2 434nmN= 4-2 486nmN = 3-2, 656nmVisible region- Balmer Series 18. Line Emission Spectroscopy Line Emission Spectra for Hydrogen Energy supplied to atoms Electrons excited - ground to excited states Electrons exist fixed energy level (quantum) Electrons transition from higher to lower, emit energy of particular wavelength/frequency - photon Higher the energy level, smaller the difference in energy bet successive energy level. Spectrum converge (get closer) with increase freq. Lines spectrum converge- energy levels also converge Ionisation energy determined (Limit of convergence)UV region Lyman Series n= n= 1Visible region Balmer Series n= n= 2IR region Paschen Series n= n= 3Line Emission Spectra Energy supplied Electrons surround nucleus in allowed energy states (quantum) Excited electron return to lower energy level, photon with discrete energy/wavelength (colour) given out. Light pass through spectroscope (prism/diffraction grating) to separate out diff colours Videos on line emissionN= 6-2 410nmClick here to view videoClick here to view videoN= 5-2 434nmN= 4-2 486nmN = 3-2, 656nmVisible region- Balmer Series 19. Hydrogen Emission Spectroscopy Visible region (Balmer Series) Line Emission Spectra for HydrogenExcited state5 4 32 Visible region Balmer Series n= n= 2 Ground stateClick here for detail notes1Click here video line emission spectrum 20. Hydrogen Emission Spectroscopy Visible region (Balmer Series) Line Emission Spectra for Hydrogen Hydrogen discharge tubeExcited state5 4 32 Visible region Balmer Series n= n= 2 Ground stateClick here for detail notes1Click here video line emission spectrumHydrogen Emission Spectroscopy 21. Hydrogen Emission Spectroscopy Visible region (Balmer Series) Line Emission Spectra for Hydrogen Hydrogen discharge tubeExcited stateHydrogen Emission Spectroscopy5 4 3 n= 5-2n = 3-2n= 4-22 = 434nmVisible region Balmer Series n= n= 2 Ground state1f = c/ = 3 x 108/434 x 10-9 = 6.90 x 1014 Hz = 486nm = 656nmf = c/ = 3 x 108/656 x 10-9 = 4.57 x 1014 HzE = hf = 6.62 x 10-34 x 6.90 x 1014 = 4.56 x 10-19 JMore energetic violet lineClick here for detail notesClick here video line emission spectrumE = hf = 6.62 x 10-34 x 4.57 x 1014 = 3.03 x 10-19 JLess energetic red line 22. Bohr Model for Hydrogen Atom Ionization Energy Bohr ModelEnergy levelElectronic Transition bet levelsNiels Bohr Model (1913) Electrons orbit nucleus. Orbits with discrete energy levels Quantized. Transition electron bet diff levels by absorb/emit radiation with frequency, f determined by energy diff bet levels -E = hf Energy light emit/absorb equal to diff bet energy levels 23. Bohr Model for Hydrogen Atom Ionization Energy Bohr ModelEnergy levelElectronic Transition bet levelsNiels Bohr Model (1913) Electrons orbit nucleus. Orbits with discrete energy levels Quantized. Transition electron bet diff levels by absorb/emit radiation with frequency, f determined by energy diff bet levels -E = hf Energy light emit/absorb equal to diff bet energy levelsLight emitted equal to difference bet energy levels, -E = hfIonization energy Transition electron from 1 ->Plank equationHigher energy level n, smaller the difference in energy bet successive energy level.5 4 3E = hfLight given off2Light energy - E = hf Frequency = E/h1 24. Bohr Model for Hydrogen Atom Ionization Energy Energy levelBohr ModelElectronic Transition bet levelsNiels Bohr Model (1913) Electrons orbit nucleus. Orbits with discrete energy levels Quantized. Transition electron bet diff levels by absorb/emit radiation with frequency, f determined by energy diff bet levels -E = hf Energy light emit/absorb equal to diff bet energy levelsLight emitted equal to difference bet energy levels, -E = hfIonization energy Transition electron from 1 ->Plank equationHigher energy level n, smaller the difference in energy bet successive energy level.5 4 3E = hf2Light given offLight energy - E = hf Frequency = E/h1 line convergeUV region Lyman Series n= n= 1Increase freq Line spectrum converge (get closer) with increase freq Ionisation energy determined (Limit of convergence)line convergeVisible region Balmer Series n= n= 2Increase freq Line spectrum converge (get closer) with increase freqLines in spectrum converge- energy levels also converge 25. Energy Level/Ionization Energy CalculationFormula - energy level, n (eV)n = energy level554433122Energy level, n= 3 = -13.6/n2 = -13.6/32 = -1.51 eV3Energy level, n= 2 = -13.6/n2 = -13.6/22 = -3.4 eV4Energy level, n= 1 = -13.6/n2 = -13.6/1 = -13.6 eV2constant 10-19 J1eV 1.6 x h = 6.626 x 10-34 Js11 26. Energy Level/Ionization Energy CalculationFormula - energy level, n (eV)n = energy level554433122Energy level, n= 3 = -13.6/n2 = -13.6/32 = -1.51 eV3Energy level, n= 2 = -13.6/n2 = -13.6/22 = -3.4 eV4Energy level, n= 1 = -13.6/n2 = -13.6/1 = -13.6 eV2constant 10-19 J1eV 1.6 x h = 6.626 x 10-34 Js11Higher energy level, n - more unstable electron - More + ve ( less negative) - More energetic56Ionization energy Transition electron from 1 ->Lower energy level, n - more stable electron - more ve (-13.6eV) - Less energetic 27. Energy Level/Ionization Energy Calculation Energy difference bet level 3 to 2Formula - energy level, n (eV)n = energy level5 1443Energy difference, n= 3-2 = -1.51 (-3.4) eV = 1.89 eV = 1.89 x 1.6 x 10-19 J = 3.024 x 10-19 J5312Energy level, n= 3 = -13.6/n2 = -13.6/32 = -1.51 eV3Energy level, n= 2 = -13.6/n2 = -13.6/22 = -3.4 eV4Energy level, n= 1 = -13.6/n2 = -13.6/1 = -13.6 eVLight given off 2Light energy - E = hf Frequency, f = E/h22constant 310-19 JFrequency, f = E/h f = 3.024 x 10-19 /6.626 x 10-34 = 4.56 x 1015 Hz4 = c/f = 3 x 108/4.56 x 1015 = 657 x 10-9 = 657nm1eV 1.6 x h = 6.626 x 10-34 Js11Higher energy level, n - more unstable electron - More + ve ( less negative) - More energetic5Light given off6Ionization energy Transition electron from 1 ->Lower energy level, n - more stable electron - more ve (-13.6eV) - Less energetic 28. Ionization Energy for Hydrogen Atom1n = energy level5 5443Ionization energy Min energy to remove 1 mole electron from 1 mole of element in gaseous state M(g) M+ (g) + e32Ionization energy Transition electron from 1 ->Energy Absorb22 3Energy level, n= = -13.6/n2 = -13.6/ = o eV4Energy level, n= 1 = -13.6/n2 = -13.6/1 = -13.6 eVelectron Light/photon ABSORB by electron11 29. Ionization Energy for Hydrogen Atom1n = energy level5 5443Ionization energy Min energy to remove 1 mole electron from 1 mole of element in gaseous state M(g) M+ (g) + e32Ionization energy Transition electron from 1 ->Energy Absorb22 3Energy level, n= = -13.6/n2 = -13.6/ = o eV4Energy level, n= 1 = -13.6/n2 = -13.6/1 = -13.6 eVelectron Light/photon ABSORB by electron1156Energy difference, n= 1-> = 0 (-13.6) eV = 13.6 eV = 13.6 x 1.6 x 10-19 J = 2.176 x 10-18 J for 1 electronEnergy absorb for 1 MOLE electron - 2.176 x 10-18 J - 1 electron - 2.176 x 10-18 x 6.02 x 1023 J - 1 mole - 1309kJ mol-1 30. Light given off, electronic transition from high -> low level Light given offEnergy ReleasedIonization Energy for Hydrogen Atom 1n = energy level5Energy difference, n= 3-2 = -1.51 (-3.4) eV = 1.89 eV = 1.89 x 1.6 x 10-19 J = 3.024 x 10-19 J2443Energy difference bet level 3 to 21 5Ionization energy Min energy to remove 1 mole electron from 1 mole of element in gaseous state M(g) M+ (g) + e32Ionization energy Transition electron from 1 ->Light given offEnergy Absorb22 33Frequency, f = E/h f = 3.024 x 10-19 /6.626 x 10-34 = 4.56 x 1015 Hz4Energy level, n= 1 = -13.6/n2 = -13.6/1 = -13.6 eVLight energy - E = hf Frequency, f = E/h4Energy level, n= = -13.6/n2 = -13.6/ = o eVelectron Light/photon ABSORB by electron1 51 = c/f = 3 x 108/4.56 x 1015 = 657 x 10-9 = 657nmLight given off56Energy difference, n= 1-> = 0 (-13.6) eV = 13.6 eV = 13.6 x 1.6 x 10-19 J = 2.176 x 10-18 J for 1 electronEnergy absorb for 1 MOLE electron - 2.176 x 10-18 J - 1 electron - 2.176 x 10-18 x 6.02 x 1023 J - 1 mole - 1309kJ mol-1 31. Energy Level/Ionization Energy Calculationn = energy levelEnergy/Wavelength Plank/Rydberg EquationFormula Plank Equation5544E = hf33Rydberg Equation to find wavelength22R = Rydberg constant R = 1.097 x 107 m-1 11Nf = final n level Ni = initial n level 32. Energy photon- high -> low level 1Electron transition from 3 -> 2Energy Level/Ionization Energy Calculationn = energy levelEnergy/Wavelength Plank/Rydberg EquationLight given offFormula Plank Equation5 Rydberg Eqn find wavelength emit 544E = hf33Rydberg Equation to find wavelength222nf = 2, ni = 3 R = 1.097 x 107 3R = Rydberg constant R = 1.097 x 107 m-1 45 = 657 x 10-9 = 657 nm f = c/ = 3 x 108/657 x 10-9 = 4.57 x 1014 HzLight given off11Nf = final n level Ni = initial n level 33. Energy photon- high -> low level 1Electron transition from 3 -> 2Energy Level/Ionization Energy Calculationn = energy levelEnergy/Wavelength Plank/Rydberg EquationLight given offFormula Plank Equation5 Rydberg Eqn find wavelength emit 544E = hf33Rydberg Equation to find wavelength222nf = 2, ni = 3 R = 1.097 x 107 3R = Rydberg constant R = 1.097 x 107 m-1 45 = 657 x 10-9 = 657 nm f = c/ = 3 x 108/657 x 10-9 = 4.57 x 1014 Hz11Click here on energy calculationLight given offClick here to view videoClick here to view videoNf = final n level Ni = initial n level 34. Light given off, high -> low level Energy photon-electronic transition from high -> low level 1Electron transition from 3 -> 2n = energy level5Light given off44332Rydberg Eqn find wavelength emit 522nf = 2, ni = 3 R = 1.097 x 107 345 = 657 x 10-9 = 657 nm f = c/ = 3 x 108/657 x 10-9 = 4.57 x 1014 HzLight given off11 35. Light given off, high -> low level Energy photon-electronic transition from high -> low level 1Electron transition from 3 -> 2Ionization Energy for Hydrogen Atom 1n = energy level5 Rydberg Eqn find wavelength emitLight given off 5443Ionization energy Min energy to remove 1 mole electron from 1 mole of element in gaseous state M(g) M+ (g) + e3Ionization energy Transition electron from 1 -> 12Energy Absorb22nf = 2, ni = 3 R = 1.097 x 107Rydberg Eqn find ionization energy33electron Light/photon ABSORB by electron 4 = 657 x 10-9 = 657 nm1nf = , ni = 1 R = 1.097 x 1071 45f = c/ = 3 x 108/657 x 10-9 = 4.57 x 1014 HzLight given off 36. Light given off, high -> low level Energy photon-electronic transition from high -> low level 1Electron transition from 3 -> 2Ionization Energy for Hydrogen Atom 1n = energy level5 Rydberg Eqn find wavelength emitLight given off 5443Ionization energy Min energy to remove 1 mole electron from 1 mole of element in gaseous state M(g) M+ (g) + e3Ionization energy Transition electron from 1 -> 12Energy Absorb22nf = 2, ni = 3 R = 1.097 x 107Rydberg Eqn find ionization energy33electron Light/photon ABSORB by electron 41 = 657 x 10-9 = 657 nmnf = , ni = 1 R = 1.097 x 1071 45f = c/ = 3 x 108/657 x 10-9 = 4.57 x 1014 Hz = 9.11 x 10-8 7Light given offEnergy absorb for 1 MOLE electron - 2.179 x 10-18 J - 1 electron - 2.179 x 10-18 x 6.02 x 1023 J - 1 mole - 1312kJ mol-16Energy, E = hf = 6.626 x 10-34 x 3.29 x 1015 = 2.179 x 10-18 J for 1 electron5f = c/ = 3 x 108/9.11 x 10-8 = 3.29 x 1015 Hz 37. Continuous Spectrum Vs Line SpectrumEmission Line Spectrum Spectrum with discrete wavelength/ frequency Excited electrons drop from higher to lower energy levelContinuous Spectrum Light spectrum with all wavelength/frequencyExcellent simulation on emission spectrumClick here to view excellent simulationClick here to view simulationEmission line spectrum for different elementsClick here spectrum for diff elementsClick here spectrum for diff elementClick here to view simulation Video on quantum mechanicsClick here on quantum mechanic, structure of atom 38. Acknowledgements Thanks to source of pictures and video used in this presentation Thanks to Creative Commons for excellent contribution on licenses http://creativecommons.org/licenses/Prepared by Lawrence Kok Check out more video tutorials from my site and hope you enjoy this tutorial http://lawrencekok.blogspot.com