Home - Periodic Tables
For fluorescent bulbs.
(Gr. kryptos, hidden) Discovered in 1898 by Ramsay and Travers in the residue left
after liquid air had nearly boiled away. In 1960 it was internationally agreed that the
fundamental unit of length, the meter, should be defined in terms of the orange-red
spectral line of 86Kr. This replaced the standard meter of Paris, which was defined in
terms of a bar made of a platinum-iridium alloy. In October 1983 the meter, which
originally was defined as being one ten millionth of a quadrant of the earth's polar
circumference, was again redefined by the International Bureau of Weights and Measures as
being the length of a path traveled by light in a vacuum during a time interval of
1/299,792,458 of a second.
Krypton is present in the air to the extent of about 1 ppm. The atmosphere of Mars has
been found to contain 0.3 ppm of krypton. Solid krypton is a white crystalline substance
with a face-centered cubic structure which is common to all the "rare gases."
It is one of the "noble" gases. It is characterized by its brilliant green
and orange spectral lines.
Naturally occurring krypton contains six stable isotopes. Seventeen other unstable
isotopes are now recognized. The spectral lines of krypton are easily produced and some
are very sharp. While krypton is generally thought of as a rare gas that normally does not
combine with other elements to form compounds, it now appears that the existence of some
krypton compounds is established. Krypton difluoride has been prepared in gram quantities
and can be made by several methods. A higher fluoride of krypton and a salt of an oxyacid
of krypton also have been reported. Molecule-ions of ArKr+ and KrH+ have been identified
and investigated, and evidence is provided for the formation of KrXe or KrXe+.
Krypton clathrates have been prepared with hydroquinone and phenol. 85Kr has found
recent application in chemical analysis. By imbedding the isotope in various solids,
kryptonates are formed. The activity of these kryptonates is sensitive to chemical
reactions at the surface. Estimates of the concentration of reactants are therefore made
possible. Krypton is used in certain photographic flash lamps for high-speed photography.
Uses thus far have been limited because of its high cost. Krypton gas presently costs
Sources: CRC Handbook of Chemistry
and Physics and the American Chemical Society.