Chapter6_1

# Chapter6_1 - CHEMISTRY 1307 Chapter VI The Structure of...

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10/5/2011 1 1 CHEMISTRY 1307 Chapter VI The Structure of Atoms 2 Electromagnetic Radiation Electromagnetic Radiation or Light is composed of two orthogonal vectors: An ____________ and a _____________ . 3 wavelength wavelength Ultraviolet radiation Amplitude Node The intensity of light is a function of the wave s _________ . A point of zero amplitude is called a ________ . Electromagnetic Radiation

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10/5/2011 2 4 Electromagnetic Radiation The frequency of light is represented by the Greek letter nu , has units of ____________ or Hertz (s -1 ) All radiation obeys the relationship: = c ________ wavelength, _______ frequency ________ wavelength, _______ frequency Wavelength and frequency are inversely proportional. 5 Electromagnetic Radiation Wavelength has units of length: m… m… nm… pm Frequency has units of inverse time: s -1 or Hz (hertz) (m) (s –1 ) = c (m s –1 ) c , the speed of electromagnetic radiation (______) moving through a vacuum is: 2.99792458 10 8 m/s c ν = λ c λ = ν or 6 Electromagnetic Radiation Long wavelength = low frequency Short wavelength = high frequency increasing ________ increasing ________
10/5/2011 3 7 Electromagnetic Radiation The ___________ of the electromagnetic spectrum is only a small portion of the entire spectrum. 8 Electromagnetic Radiation Problem: Visible red light has a wavelength ( ) of 685 nm, calculate the frequency. 8 14 1 -7 m 3.00 10 c s frequency ( ) 4.38 10 sec 6.85 10 m 1 m 7 685 nm 6.85 10 m 9 1 10 nm 9 Quantization of Energy E = _____ Energy of radiation is proportional to frequency h = Planck s constant = 6.6262 x 10 -34 J·s An object can gain or lose energy by absorbing or emitting radiant energy in _______ . A quanta of energy is the smallest unit of energy that may be exchanged between oscillators or emitted as radiation. It is too small to be observed in the classical world in which we live.

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10/5/2011 4 10 Quantization of Energy Light with a short (high ) has a _____ Energy Light with long (low ) has a ______ Energy E = h · 11 Planck’s Law = × ν E h × = λ h c E ____ Light , (higher frequency) has more energy than ____ Light , with a lower frequency. c ν = λ and yields: • As the ________ of light increases, the energy of the photon increases • As the ________ of light increases, the energy of the photon decreases. 12 Energy of Radiation Problem: Calculate the energy of 1.00 mol of photons of red light at 685 nm units of kJ/mol. The energy of a photon in units of kJ/mol can be determined by converting units of wavelength to frequency to energy using Planck s law and Avogadro's number via dimensional analysis.
10/5/2011 5 13 Quantization of Energy = × ν photon E h × = λ h c Problem: Calculate the energy of 1.00 mol of photons of red light at 685 nm units of kJ/mol.

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Chapter6_1 - CHEMISTRY 1307 Chapter VI The Structure of...

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