Summarizing Quantization of Energy

Quantization of Energy Summary

• The first indication that energy is sometimes quantized came from blackbody radiation, which is the emission of EM radiation by an object with an emissivity of 1.
• Planck recognized that the energy levels of the emitting atoms and molecules were quantized, with only the allowed values of \(E=(n+\cfrac{1}{2})\text{hf}\text{,}\) where \(n\) is any non-negative integer (0, 1, 2, 3, …).
• \(h\) is Planck’s constant, whose value is \(h=6\text{.}\text{626}×{\text{10}}^{\text{–34}}\phantom{\rule{0.25em}{0ex}}\text{J}\cdot \text{s.}\)
• Thus, the oscillatory absorption and emission energies of atoms and molecules in a blackbody could increase or decrease only in steps of size \(\Delta E=\text{hf}\) where \(f\) is the frequency of the oscillatory nature of the absorption and emission of EM radiation.
• Another indication of energy levels being quantized in atoms and molecules comes from the lines in atomic spectra, which are the EM emissions of individual atoms and molecules.

Glossary

blackbody

an ideal radiator, which can radiate equally well at all wavelengths

blackbody radiation

the electromagnetic radiation from a blackbody

Planck’s constant

\(h=6\text{.}\text{626}×{\text{10}}^{\text{–34}}\phantom{\rule{0.25em}{0ex}}\text{J}\cdot \text{s}\)

atomic spectra

the electromagnetic emission from atoms and molecules