KEY - Electromagnetic
Honors Chemistry:
Radiation Calculations
Speed of light:
c = λν
λ= c/ν
ν=c/λ
c = 3.00 x108 m/s
Energy:
E = hν = hc/ λ
h = 6.63 x 10-34 Js
1. What is the frequency of a photon of energy that has a wavelength of 6.20 x 10 -7 m? Use
your continuous spectrum to determine its color.
λ = 6.20(10-7) m or 620nm (yellow)
ν = c / λ = 3(108) / 6.2(10-7) = 0.484 (1015) = 4.84 (1014) Hz
2. Gamma radiation has a frequency of 3x1020 Hz while ultraviolet radiation has a frequency of
8x1014 Hz. Compare the wavelengths of a photon of gamma radiation with ultraviolet
radiation. (Hz = 1/second).
λ = c/ν
λ gamma = 3(108) / 3(1020) = 1(10-12)m
λ uv = 3(108) / 8(1014) = 0.375(10-6)m = 3.75 (10-7)m
Wavelength and frequency have an inverse relationship.
3. Calculate the energy of a photon of energy that has a frequency of 2.5x1016 Hz.
E = hν
E = 6.63(10-34) * 2.5 (1016) = 16.58 (10-18) J = 1.658(10-17)J
4. A photon of blue-green light has an energy of 4.4x10-19 J. What is the wavelength of this
light?
E = hc/ λ
λ = hc/ E
λ = 6.63(10-34) 3(109) / 4.4 (10-19) = 4.52 (10-7)m or 452nm
5. Determine the energy of an X-ray that has a wavelength of 1x10-10m.
E = hc/ λ
6.
E = 6.63(10-34) 3(108) / 1(10-10) = 19.89(10-16)J = 1.99 (10-15)J
Describe the events that occur in an atom when energy is applied to it. What accounts for
the phenomena of the emission of discrete wavelengths of light by excited atoms? Use the
embedded model to help you in your explanation.