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CHEM 121 Studioby Learn4Less · UBC CHEM 121

CHEM 121 glossary

Electromagnetic spectrum

The full range of light, ordered by wavelength: gamma rays, X-rays, ultraviolet, visible, infrared, microwave and radio. All travel at cc in a vacuum; shorter wavelength means higher frequency and more energetic photons.

The electromagnetic spectrumFrom left to right: gamma rays, X-rays, ultraviolet, visible light, infrared, microwaves, radio waves. Wavelength increases to the right; frequency and photon energy increase to the left. Visible light spans about 400 nm (violet) to 700 nm (red).γ-rayX-rayUVIRmicrowaveradio400 nmvisible700 nmlonger wavelength →← higher frequency and photon energy

Example

A 100 nm UV photon carries 1.99×10−181.99\times10^{-18} J (1196 kJ/mol, enough to break any bond), while a 10 μm infrared photon carries only about 12 kJ/mol, enough to make molecules vibrate.