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Unformatted text preview: J . s 3. The only energies a vibrat ing atom can have are: hn, 2hn, 3hn, 4hn…) PLANCK’S CONCLUSION:
· THE VIBRATIONAL ENERGIES OF THE ATOMS ARE QUANTIZED (the possible energies of atoms are limited to certain values) 8 Chemistry 101 Chapter 7 THE DUAL NATURE OF LIGHT
· Traditionally: Light was considered to be made o f waves Einstein rationalized that:
· If a vibrat ing atom changed energy (say from 3hn to 2hn): Ø the energy o f the atom would decrease by hn, Ø a quantum of light energy equal to hn would be emitted, Ø (called this quantum of energy a photon) Einstein postulated that:
· Light consists of quanta of energy, called photons, which are particles of electromagnet ic energy (particles o f light) E = hn where E = energy of photon (light particle) h = Planck’s constant (6.63 x 10-34 J . s) n = frequency o f light CONCLUSION LIGHT HAS A DUAL NATURE PARTICLE NATURE and This is illustrated by the formula: WAVE NATURE E = h n E = energy of a light particle (a photon) n = the frequency of the associated light wave 9 Chemistry 101 Chapter 7 Examples: 6
1. What is the energy o f a photon corresponding to radio waves of frequency 1.255 x 10 s–1 ? 6
u = 1.255 x 10 s–1 E = h u h = 6.63 x 10-34 J . s 6
E = (6...
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