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 in a discharge tube displays its green and
orange spectral signature. Gaseous krypton is colorless, while solid
krypton is white. Credit: Pslawinski, Wikipedia
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.
|relative atomic mass
||3.73 kg/m3 (0 °C)