Chapter7_8_QuantumMechanics_PeriodicProperties

Chapter7_8_QuantumMechanics_PeriodicProperties - CHAPTER 7...

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1 Quantum Mechanics and Periodic Properties of Elements
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2 Electromagnetic radiation Energy can be transferred as Work Heat Electromagnetic radiation Oscillating waves containing perpendicular electric and magnetic conponents Visible light Ultraviolet light Infrared light γ rays X rays Microwaves
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3 Electromagnetic radiation All electromagnetic waves travel at the speed of light (c = 2.99792 x 10 8 m/s) in a vacuum. Wavelength ( λ 29 distance between two neighboring peaks. Measured in units of distance such as m, cm, nm , Å . source
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4 Description of Electromagnetic Radiation F requency requency ( ν , the Greek letter nu ) is the number of crests or troughs that pass a given point per second. Measured in units of 1/time s -1 (Hz), min -1 , etc.
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5 Description of Electromagnetic Radiation Frequency and wavelength of a wave are inversely related to each other. velocity of a wave = λ ν . For electromagnetic radiation: c = λ ν
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Tro, Chemistry: A Molecular Approach 6 Color the color of light is determined by its wavelength or frequency white light is a mixture of all the colors of visible light a spectrum R ed O range Y ellow G reen B lue V iolet (Roy G BIV) when an object absorbs some of the wavelengths of white light while reflecting others, it appears colored the observed color is predominantly the colors reflected
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Tro, Chemistry: A Molecular Approach 7 Electromagnetic Spectrum
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Which one of the following has the highest frenquency? Which one has longest wavelength? Red ; Green ; Violet ; Ultra Violet (UV) 8 A . B . C . D . E . 20% 20% 20% 20% 20% A. Red for highest ν and longest λ ; B. UV for highest ν and longest λ ; C. Red for highest ν , and UV for longest λ D. UV for highest ν , and Green for longest λ E. UV for highest ν , and Red for longest λ
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9 The Photoelectric Effect Light can strike the surface of some metals causing electrons to be ejected.
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10 Particle Nature of Electromagnetic Waves To explain the photoelectric effect, Einstein proposed that electromagnetic radiation can be viewed as a stream of tiny packets of energy called photons . ( Energy is quantized .) The energy of one photon is proportional to the frequency of the electromagnetic wave: E = h ν where h is Planck’s constant, 6.63 × 10 −34 J-s.
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Tro, Chemistry: A Molecular Approach 11 Ejected Electrons 1 photon at the threshold frequency has just enough energy for an electron to escape the atom. (= first ionization energy, IE1) binding energy, φ for higher frequencies, the electron absorbs more energy than is necessary to escape this excess energy becomes kinetic energy of the ejected electron Kinetic Energy = E photon – E binding
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12 Electromagnetic Radiation Example : What is the energy of a photon of green light with wavelength 5200 Å ? What is the energy of 1.00 mol of these photons?
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13 Atomic Spectra When an electric spark passes through a gas at low pressure, it gives off emission spectrum , or line spectrum.
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This note was uploaded on 05/05/2010 for the course BIO 101 taught by Professor Vaughan during the Spring '10 term at IUPUI.

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Chapter7_8_QuantumMechanics_PeriodicProperties - CHAPTER 7...

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