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Unformatted text preview: engths such as white light). Light can also be
described in terms of bundles of energy called photons. Each photon has an energy, E, proportional to its
E = hν
In this equation, h is Planck's constant, 6.626 × 10-34 J · s. If all of the colors in the visible spectrum are
mixed, the result appears as white light. When a material appears colored, you are selectively seeing some
wavelengths (or frequencies, or energies) and not others. Colors can arise from two different, but closely related,
processes that can be understood at the atomic and molecular level. These processes are abs orption and
e mis s ion.
Electrons in atoms, molecules, and ions ordinarily occupy the lowest energy orbitals that are
available to them. This lowest energy configuration is called the ground s tate . However, when the atom,
molecule or ion absorbs energy, one of its electrons can be promoted from a low energy orbital into a higher
energy orbital and produce what is called an e xcite d s tate . Atoms, molecules and ions can absorb or emit
energy in the f...
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This document was uploaded on 01/22/2014.
- Spring '14