Chem Test 1 - o Electromagnetic Radiation Waves are...

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Electromagnetic Radiation o Waves are characterized by: Wavelength – distance between 2 consecutive peaks/troughs in a wave m Greek letter lambda Frequency – number of waves (cycles) per second that pass a given point in space 1/s, s -1 , hertz (Hz) Greek letter nu Speed – all EM-Rad travels at speed of light (about 3.0 x 10 8 m/s) o EM-Rad classified into types according to the frequency of the wave Nature of Matter o Bohr realized that the photon that is emitted is due to the energy difference in quantum levels within the atom o Planck’s constant = 6.626 x 10 -34 J s o Energy can be gained or lost only in integer multiples of size h v , called quanta
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ΔE = nhv Physicists had always assumed the energy of matter was continuous, which meant that the transfer of any quantity of energy was possible o Two views of EM-Rad: Wave model The oscillations of the waves of EM-Rad are perpendicular to the direction of energy transfer and travel Light usually has a spectrum of frequencies which sum together to form the resultant wave Different frequencies undergo different angles of refraction What type of excitations go with the various radiation types o Visible and UV – yield electronic excitations in atoms o IR – vibrational excitations
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Line Spectra Nature of Matter o Emission – formed when e- transitions to a lower energy state Emits a photon of a particular E and λ o Absorption – formed when e- transitions to a higher energy state Photon is absorbed in the process o Released or absorbed photon has E = energy difference between the levels. o
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This note was uploaded on 02/25/2011 for the course CH 301 taught by Professor Fakhreddine/lyon during the Spring '07 term at University of Texas.

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Chem Test 1 - o Electromagnetic Radiation Waves are...

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