A substance has a band gap of 6.9 eV at 273 K. Is this substance best classified as an insulator, a semiconductor, or a metal?
Ch.13 - Solids & Modern Materials
Chapter 13, Problem 68
What is the wavelength of light (in nm) emitted when an electron moves from the conduction band to the valence band in a sample of diamond, which has a band gap of 5.5 eV?

1
Convert the band gap energy from electron volts (eV) to joules (J) using the conversion factor: 1 eV = 1.602 x 10^{-19} J.
Use the energy-wavelength relationship given by the equation: E = \frac{hc}{\lambda}, where E is the energy in joules, h is Planck's constant (6.626 x 10^{-34} J·s), c is the speed of light (3.00 x 10^8 m/s), and \lambda is the wavelength in meters.
Rearrange the equation to solve for wavelength: \lambda = \frac{hc}{E}.
Substitute the values for h, c, and the converted energy E into the equation to calculate the wavelength in meters.
Convert the wavelength from meters to nanometers by multiplying by 10^9, since 1 meter = 10^9 nanometers.
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Band Gap Energy
The band gap energy is the energy difference between the conduction band and the valence band in a solid material. It determines the electrical conductivity and optical properties of the material. In semiconductors and insulators, a larger band gap typically means that the material is less conductive and can absorb higher energy photons, which is crucial for understanding electron transitions.
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Intepreting the Band of Stability
Photon Energy and Wavelength Relationship
The energy of a photon is inversely related to its wavelength, described by the equation E = hc/λ, where E is energy, h is Planck's constant, c is the speed of light, and λ is the wavelength. This relationship allows us to calculate the wavelength of light emitted when an electron transitions between energy bands, as the energy lost during the transition is emitted as a photon.
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Frequency-Wavelength Relationship
Electron Transition in Semiconductors
In semiconductors, when an electron moves from the conduction band to the valence band, it releases energy in the form of light (photons). This process is fundamental in understanding how materials like diamond emit light when excited, and the energy of the emitted light corresponds to the band gap energy of the material, which in this case is 5.5 eV for diamond.
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Electron Configurations Of Transition Metals Example
Related Practice
Textbook Question
Textbook Question
Indicate if each solid forms an n-type or a p-type semiconductor.
a. silicon doped with gallium
b. germanium doped with antimony
Textbook Question
Does a photon of red light with a frequency of 4.29⨉1014 Hz have sufficient energy to promote an electron from the valence band to the conduction band in a sample of silicon (the band gap in silicon is 1.11 eV)?
Textbook Question
Teflon is an addition polymer formed from the monomer shown here. Draw the structure of the polymer.
Textbook Question
Saran, the polymer used to make saran wrap, is an addition polymer formed from two monomers—vinylidene chloride and vinyl chloride. Draw the structure of the polymer. (Hint: The monomers alternate.)
Textbook Question
Polyacrylonitrile (PAN) is an addition polymer with the struc- ture shown here. Draw the structure of the monomer.