Krypton

General properties
Name, symbol, number	krypton, Kr, 36
Element category	noble gases
Group, period, block	18, 4, p
Standard atomic weight	83.798
Electron configuration	[Ar] 3d10 4s2 4p6 2, 8, 18, 8
History
Discovery	William Ramsay and Morris Travers (1898)
First isolation	William Ramsay and Morris Travers (1898)

Krypton (from Greek: κρυπτόςkryptos "the hidden one") is a chemical element with symbol Kr and atomic number 36. It is a member of group 18 (noble gases) elements. A colorless, odorless, tasteless noble gas, krypton occurs in trace amounts in the atmosphere, is isolated by fractionally distilling liquified air, and is often used with other rare gases in fluorescent lamps. Krypton is inert for most practical purposes.

Krypton, like the other noble gases, can be used in lighting and photography. Krypton light has a large number of spectral lines, and krypton's high light output in plasmas allows it to play an important role in many high-powered gas lasers (krypton ion and excimer lasers), which pick out one of the many spectral lines to amplify. There is also a specific krypton fluoride laser. The high power and relative ease of operation of krypton discharge tubes caused (from 1960 to 1983) the official length of a meter to be defined in terms of the 605 nm (red-orange) spectral line of krypton-86.

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