In 1898, krypton was discovered when liquefied atmospheric
gases were carefully analyzed. Up until this time, only
helium (1868) and
argon (1894) had been discovered.
But because of their wide difference in atomic masses of
(atomic mass = 4.0026 amu for helium and
(atomic mass = 39.948 amu for argon), it was suspected that more gaseous elements belonging
to this group of gases existed. The cold residues that remained after the liquid helium and
argon were drawn off were carefully examined. Using
fractional distillation, this experiment yielded the
discovery of a new noble gas, krypton. Its name
is from the Greek word, kryptos, meaning "hidden". This method, incidentally, was also
used to discover neon a few weeks later.
Krypton is a dense, colorless, odorless atmospheric gas. It ranks
seventh on the list of gases in the earth's atmosphere.
Today, the gas is still captured and separated for commercial and laboratory applications by
fractional distillation of liquid air. Shown above is the
glow discharge of krypton gas.
None of the naturally occurring isotopes of krypton is radioactive. The radioactive isotopes
of krypton are produced artificially as byproducts of nuclear power plants.
It is used to keep track of Soviet nuclear production by subtracting off the amount
that is generated from the reactors of the Western world from the total in the air.
Krypton-85 is used as a low-cost source of radiation for industrial thickness gauges and
leak-testing instruments.
The International Committee of Weights and Measures once used Krypton-86 as the
basis of the international definition of a meter. The meter was
once defined in terms of the vacuum wavelength of the radiation corresponding to the transition
between two atomic levels of the krypton isotope.
The commercial applications of kryton include its
use as inert filler-gas in incandescent bulbs, and fluorescent lamps. The most important
application is in the flashing stroboscopic lamps that light up airport runways during hours
of darkness.
As for Superman's strength-zapping nemesis, kryptonite, the resemblance of the name to
krypton the element is purely coincidental.
