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CHEM 121 Studioby Learn4Less · UBC CHEM 121

CHEM 121 glossary

Line spectrum

A spectrum made of sharp lines at a few specific wavelengths, rather than a continuous rainbow. Each line is a photon with hν=∣ΔE∣h\nu = |\Delta E| between two allowed energy levels, so the pattern is a fingerprint of the element.

Line spectrumBright emission lines at 447 nm, 471 nm, 492 nm, 502 nm, 588 nm, 668 nm, 707 nm.← UVIR →< 380 nm> 750 nm400450500550600650700750wavelength (nm)447 nm471 nm492 nm502 nm588 nm668 nm707 nm

The visible emission lines of helium.

Example

Helium was discovered in 1868 from an unexplained yellow line at about 588 nm in the Sun's spectrum, before it was ever isolated on Earth.

See alsoEmission spectrumAbsorption spectrumEnergy levelQuantization