krypton (Kr)


Krypton in a discharge tube displays its green and orange spectral signature. Gaseous krypton is colorless, while solid krypton is white.

Krypton (Kr) is a colorless, odorless, highly unreactive gaseous element discovered by William Ramsey and M. W. Travers in London in1898; its name comes from the Greek kryptos, meaning 'hidden.' It is a member of the noble gas family (abundance 1.1 × 10-3%). It is obtained pure by fractional distillation of air. Krypton is used chiefly (with argon) in gas-discharge lamps, fluorescent lights, and electronic flash tubes. The isotope 86Kr has a spectral line used, from 1960 to 1983, as the standard measure of length. One meter is defined as 1,650,763.73 wavelengths of this line.


Krypton-81 in medicine

Krypton-81m, the shortest-lived isotope of krypton (half-life 13 seconds), and the shortest-lived isotope used in medicine, can be used to investigation the ventilation of the lungs. The patient breathes a small quantity of the gas, the arrival of which in different parts of the lungs is recorded by a gamma camera. This test is often performed as part of ventilation-perfusion scanning to look for pulmonary emboli.


Chemistry of krypton

Krypton forms a limited range of chemical compounds and some clathrates. It combines with fluorine in an electric discharge to give krypton (II) fluoride (KrF2), a highly reactive, odorless crystalline solid, which decomposes slowly at 20°C, is hydrolyzed by water, and forms adducts with Lewis acid fluorides, e.g. KrF2·2SbF5. KrF2 is used as a strong fluorinating agent.


atomic number 36
relative atomic mass 83.80
electron configuration 1s22s22p63s23p63d104s24p6
melting point -156.6°C (-249.9°F)
boiling point -152.3°C (-242.1°F)
density 3.73 kg/m3 (0 °C)