chem notes 10-31 - -approx 100 ft-am amplitude...

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October 31, 2007 Dr. Stevens Gen. Chem. 1 Electromagnetic radiation: 10^-12 – gamma rays 10^-10 – X-ray 10^-9 – UV 10^-7 – visible 10^-4 – infra-red 10^-2 – microwaves 10 10^2 – tv/radio (fm/am) Gamma rays: -very high energy, b/c very short wavelengths -medical uses -cosmic radiation X-rays: -very short wavelength, so very high energy -medical uses -harmful to cells -don’t travel far – scatter quickly UV: -slightly shorter wavelength than visible light -harmful to cells (in large doses) – cancer -kill bacteria -SPF: -sub protection factor -SPF 4: ¼ light gets to you -SPF 50: 1/50 UV gets to you Visible light (400-700 nanometers): -color order: VBGYOR Infrared: -slightly longer than visible wavelength -heat – given off by all warm objects -how nocturnal animals see -night vision goggles -communication signals Microwaves: -1/2” long -heating food
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-spinning/bending motion of water -food is heated by friction from the water -communication -cellphones Radio Waves:
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Unformatted text preview: -approx. 100 ft-am: amplitude modulation-longer range-fm: frequency modulation-shorter range Equations/Calculations: E=h(frequency) c=wavelength(frequency) 1. calculate energy of blue light, wavelength = 4x10^-7 m E=h(c/wavelength) E=(6.626x10^-34x2.9979x10^8)/4.0x10^-7 = 5.0x10^-19J-implicit: for one photon/quantum of light 2. convert E in kJ/mol 5.0x10^-19J/1photon x 1kJ/1000J x 6.03x10^23photons/1mol = 300kJ/mol-reference: typical bond is approx 100-900kJ/mol-blue light CAN affect some chemical bonds Scattering:-higher energy = strong scattering (travel less distance)-violet/blue = more scattered … red = less scattered-why is the sky blue?-sky is blue b/c blue light scatters more-not violet, b/c violet = blue…kinda…(deepest violet not visible to eyes b/c space=black)-sunrise/sunset – red/orange colors b/c longer wavelength = less scattering (travels further)-blue/violet lights scattered earlier b/c more atmosphere...
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