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Quantized Energy of Light. What happens when electrons move between energy levels. Electromagnetic Radiation. All EM radiation travels at the Speed of Light, c . c = 3.00 x 10 8 m/s = λν
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Quantized Energy of Light What happens when electrons move between energy levels
Electromagnetic Radiation • All EM radiation travels at the Speed of Light, c. • c = 3.00 x 108 m/s = λν • Frequency, ν, is the number of waves per second. The unit is called a Hertz (Hz) and mathematically is • Since we don’t really have a unit for a wave, the unit for frequency is: • If all EM waves travel the same speed, then the higher the frequency, the smaller each wave is. • As Frequency , Wavelength (λ) .
Quantum • The smallest amount (chunk, photon, etc.) of energy that can be released as EM radiation. • Energy is absorbed when an electron jumps up to a higher energy level and is released when it falls back down to a lower energy level.
Planck’s Constant • Max Planck’s theory of quantized energy comes from the equation: • E = hν • E = amount of energy absorbed or released. • h = Planck’s constant = 6.626 x 10-34 Js. • ν = The frequency of EM radiation emitted or absorbed. The unit is Hertz, s-1. • When the units are multiplied together:
Example • How much energy is released when a photon of red light with a frequency of 4.41 x 1014 s-1. • = 2.92x10-19 J • Not very much energy in 1 photon of light, huh?
Example 2 • A photon of Orange light, with a wavelength of 600nm is absorbed by an electron. How much energy is gained by the electron. • Since the photon data is given to us as a wavelength (nm), and the energy equation uses frequency (s-1) we have to convert wavelength to frequency using: • Finally, you can use E = hν.
Photons • Photons are packets of light energy with specific energies. These energies correspond to specific frequencies of light. • A photon of red light will have a lower frequency, and thus less energy than a photon of blue light. This can be observed when looking at flames. Most people know that a blue flame is hotter than a red/orange flame.