1 / 51

Modern Atomic Theory Electrons in the Atom Electromagnetic Spectrum

Modern Atomic Theory Electrons in the Atom Electromagnetic Spectrum. Fundamentals of Light. Neon advertising signs are formed from glass tubes bent in various shapes. An electric current passing through the gas in glass tube makes the gas glow with its own characteristic color.

lorie
Download Presentation

Modern Atomic Theory Electrons in the Atom Electromagnetic Spectrum

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Modern Atomic TheoryElectrons in the AtomElectromagnetic Spectrum

  2. Fundamentals of Light

  3. Neon advertising signs are formed from glass tubes bent in various shapes. • An electric current passing through the gas in glass tube makes the gas glow with its own characteristic color. • Why does each gas glow with a specific color of light?

  4. LIGHT The ground state is the lowest energy level that an electron can occupy.

  5. The excited state is a higher energy level that an electron may move to after absorbing energy.

  6. The amount of energyabsorbed by the electron is equal to the energy of the photon which is emitted.

  7. A quantum leapis the jump in energy level that an electron will make after absorbingthe correct quanta of energy. A quantum is a packet of energy that electrons absorb to change energy levels.

  8. Light (photons): form of some of the electromagnetic radiation (energy) released by electrons as theyreturnto their ground state from their excited state.

  9. Energy absorbed (released) see light • Energy  increases • Ground state  excited state (where electrons are suppose to be) Sun gives tremendous amount of energy (ground  excited)

  10. ELECTROMAGNETIC RADIATION • All electrons are sitting in ground state • Turn on light  electricity (goes to a higher e- level) • If electricity still on  out • Little burst of energy Lights off  Ground state Lights on  excited state (always little bursts of energy going on)

  11. Excited Gases & Atomic Structure

  12. Electromagnetic radiation.

  13. Electromagnetic radiationis a form of energy that exhibitswavelikebehavior as it travels through space.

  14. Electromagnetic Radiation • Most subatomic particles behave as PARTICLES and obey the physics of waves.

  15. Waves • Wavelength () –(Greek letter lambda), length of one complete wave (distance between crests) • Frequency () – (Greek letter nu) # of waves that pass a point during a certain time period • hertz (Hz) = 1/s • Amplitude (A) – distance from the origin to the trough or crest

  16. crest A A origin trough  Waves greater amplitude (intensity) greater frequency (color)

  17. wavelength Visible light Amplitude wavelength Node Ultaviolet radiation Electromagnetic Radiation

  18. Light • The wavelength and frequency of light are inversely proportional to each other. Low energy High Energy

  19. The Electromagnetic Spectrum

  20. Light • Sunlight consists of light with a continuous range of wavelengths& frequencies. • The electromagnetic spectrum consists of radiation over a broad band of wavelengths.

  21. ElectromagneticSpectrum In increasing energy, ROYGBIV

  22. increasing frequency increasing wavelength Electromagnetic Spectrum Long wavelength --> small frequency (low energy) Short wavelength --> high frequency (High energy)

  23. Types of EM Radiation • Radiowaves • lowest energy EM radiation • Receives in radio ( unscrambles)

  24. Types of EM Radiation • Radar • Military, space, sonar, weather • Speeding (cops) • Microwaves • penetrate food and vibrate water & fat molecules to produce thermal energy • Telephone & cell phone signals

  25. Types of EM Radiation • Infrared Radiation (IR) Used by military ( to see in dark) • slightly lower energy than visible light • can raise the thermal energy of objects • thermogram - image made by detecting IR radiation

  26. Infrared Measures Heat Every object with a temperature above absolute zero radiates in the infrared.

  27. Infrared in Society • Oceanography • Firefighting • Commercial Applications

  28. R O Y G. B I V red orange yellow green blue indigo violet Types of EM Radiation • Visible Light • small part of the spectrum we can see • ROY G. BIV - colors in order of increasing energy

  29. How to split Light: a) Prism (curve each wave length)

  30. B) Mirror & Water  wavelength of light

  31. A spectroscope: device used to view the visible wavelengths of light produced by different atoms. The wavelengths are visible as bright lineson the spectrum.

  32. Spectrum of White Light ROY G BIV

  33. Types of EM Radiation • Ultraviolet Radiation (UV) • slightly higher energy than visible light • Types: • UVA - tanning, wrinkles • UVB - sunburn, cancer • UVC - most harmful, sterilization Bumble bee Insects can see uv waves

  34. Types of EM Radiation • Ultraviolet Radiation (UV) • Ozone layer depletion = UV exposure!

  35. Types of EM Radiation • X rays • higher energy than UV • can penetrate soft tissue, but not bones • Put a lead vest over body

  36. Radiation treatment using radioactive cobalt-60. Types of EM Radiation • Gamma rays • highest energy EM radiation • emitted by radioactive atoms • used to kill cancerous cells

  37. The particular wavelength of light produced is specific for each element and can be used to identify it.

  38. Line Emission Spectra of Excited Atoms • Excited atoms emit light of only certain wavelengths • The wavelengths of emitted light depend on the element.

  39. Spectrum of Excited Hydrogen Gas

  40. Line Spectra of Other Elements

  41. Slit that allows light inside Light Spectrum Line up the slit so that it is parallel with the spectrum tube (light bulb) Scale

  42. A flame test : method used to identify and element by the color of flame it produces. Ex: copper produces a characteristic green flame.

  43. The Electric Pickle • Excited atoms can emit light. • Here the solution in a pickle is excited electrically. • The Na+ ions in the pickle juice give off light characteristic of that element.

  44. Light • Light • How are the wavelength and frequencyof light related?

  45. Electromagnetic Radiation • Waves have a frequency • Use the Greek letter “nu”, , for frequency, and units are “cycles per sec” • All radiation:  •  = c • where c = velocity of light = 3.00 x 108m/sec

  46. EM Spectrum • Frequency & wavelength are inversely proportional c =  c: speed of light (3.00  108 m/s) : wavelength (m, nm, etc.) : frequency (Hz)

  47. WORK:  = c   = 3.00  108 m/s 4.34  10-7 m EM Spectrum • EX: Find the frequency of a photon with a wavelength of 434 nm. GIVEN:  = ?  = 434 nm = 4.34  10-7 m c = 3.00  108 m/s = 6.91  1014 Hz

  48. Light • According to the wave model, light consists of electromagnetic waves. • Electromagnetic radiationincludes radio waves, microwaves, infrared waves, visible light, ultraviolet waves, X-rays, and gamma rays. • All electromagnetic waves travel in a vacuum at a speed of 2.998  108 m/s.

  49. Quantum Theory • The energy of a photon (light quanta) is proportional to its frequency. (E = h x v) E: energy (J, joules) h: Planck’s constant (6.6262  10-34 J·s) : frequency (Hz) E = h

  50. Quantum Theory • EX: Find the energy of a red photon with a frequency of 4.57  1014 Hz. • E = H x V GIVEN: E = ?  = 4.57  1014 Hz h =6.6262  10-34 J·s WORK: E = h E = (6.6262  10-34 J·s) (4.57  1014 Hz) E = 3.03  10-19 J

More Related