Ch.8 Notes - Ch. 8 I. II. III. Light Bohr Model Wave...

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Ch. 8 I. Light II. Bohr Model III. Wave (Quantum) Mechanics a. Quantum numbers b. Orbitals IV. Electron Configurations V. Atomic Properties Light Knowledge of atomic structure derived from studies of interaction of radiation (absorption or emission) with atoms Electromagnetic Radiation (energy traveling through space) Radiation has electric and magnetic properties Types: visible light, infrared, ultraviolet, radio waves, microwaves, etc o Dualistic Properties of Radiation Wave-like behavior Photon behavior (behaves like packets of energy) Wave-like Behavior o Consider an electromagnetic wave and its properties o Speed of light (3.00 x 10 8 m/s) o Amplitude o Wavelength (m, nm, cm, etc) o Frequency (cycles/s or s -1 [Hz]) Inverse Relationship between wavelength and frequency (λ x 1 /v) Larger wavelength = smaller frequency Smaller wavelength = larger frequency Speed is constant dependent on medium c= λv OR v= c/λ o Electromagnetic Spectrum Gamma 10 -11 X-rays 10 -9 Ultraviolet light 10 -7 Visible light 10 -6 (400nm) V I B G Y O R (700nm) [colors] Infrared 10 -5 Microwaves 10 -1 TV 1 Radio Waves 10 2 Photon Or Particle Behavior o Radiation as a stream of photons, each of energy, E o E=hv= h(c/λ) E-Energy of one photon or packet of energy
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H-Planck’s Constant (6.626 x 10 -34 J.s) V-Frequency (s-1) High E High v short wavelength Low E low v long wavelength Key: E is gained or lost by matter only in multiples of hv Relationship of wavelength, v, and E o Green light, traffic signal λ=522nm Find v, E(J/photon) of a photon V=c/λ =3.00 x 10 8 m/s/ 522 x 10 -9 m =5.75 x 10 14 s -1 E=hv (per photon) =(6.26 x 10 -34 J.s) (5.75 x 10 14 s-1) =3. .81 x 10 -19 J (per photon) Atomic Spectra (Line Spectra) o Radiation of discrete wavelengths (or frequencies) emitted by excited atoms Energy + Atoms Excited Atoms Light Emitted (ie. Flame, etc) A* (specific colors or specific v) Examples: Gases in discharge tubes o Hg (blue-gray) Na (yellow-orange) Neon (red) Fireworks or Flares – Sr Compounds (red) Flame tests – Cu (green) Na (yellow-orange) o Emitted Light Studied With Prism Line spectra observed Line spectrum of H is simple. Spectra of larger atoms more complex. (Used to identify elements in space) 9/12/07 Balmer and Rydberg o Equation predicting frequency of lines in H line spectrum. 1 /λ = R ( 1 / n 1 1 / n 2 ) for n>2 R=109,678 cm -1 Review o Rutherford- nuclear atom o Energy is quantized in the atom (gained or lost in multiples of hv) Ex, emission spectrum o Ryderg- empirical relationship to describe atomic spectrum of H (v = 1 / wavelength = R ( 1 / 4 1 / n 2 ) ) M= 1,2,3,4
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This note was uploaded on 07/05/2008 for the course CHEM 1311 taught by Professor Sibert during the Fall '08 term at University of Texas at Dallas, Richardson.

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Ch.8 Notes - Ch. 8 I. II. III. Light Bohr Model Wave...

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