Xenon (pronounced /ˈzɛnɒn/[2] or /'ziːnɒn/[3]) is the chemical element that has the symbol Xe and atomic number 54. A colorless, heavy, odorless noble gas, xenon occurs in the earth's atmosphere in trace amounts.[4] Although generally unreactive, xenon can undergo a few chemical reactions such as the formation of xenon hexafluoroplatinate, the first noble gas compound to be synthesized.[5][6][7]
Naturally occurring xenon consists of nine stable isotopes. There are also over 40 unstable isotopes that undergo radioactive decay. The isotope ratios of xenon are an important tool for studying the early history of the
Solar System.[8] Xenon-135 is produced as a result of nuclear fission and acts as a neutron absorber in nuclear reactors.[9]
Xenon is used in flash lamps[10] and arc lamps,[11] and as a general anesthetic.[12] The first excimer laser design used a xenon dimer molecule (Xe2) as its lasing medium,[13] and the earliest laser designs used xenon flash lamps as pumps.[14] Xenon is also being used to search for hypothetical weakly interacting massive particles[15] and as the propellant for ion thrusters in spacecraft.[16]
History
Xenon was discovered in England by William Ramsay and Morris Travers on July 12, 1898, shortly after their discovery of the elements krypton and neon. They found it in the residue left over from evaporating components of liquid air.[17][18] Ramsay suggested the name xenon for this gas from the Greek word ξένον [xenon], neuter singular form of ξένος
[xenos], meaning 'foreign(er)', 'strange(r)', or 'guest'.[19][20] In 1902, Ramsay estimated the proportion of xenon in the Earth's atmosphere as one part in 20 million.[21]
During the 1930s, engineer Harold Edgerton began exploring strobe light technology for high speed photography. This led him to the invention of the xenon flash lamp, in which light is generated by sending a brief electrical current through a tube filled
with xenon gas. In 1934, Edgerton was able to generate flashes as brief as one microsecond with this method.[10][22][23]
In 1939 Albert R. Behnke Jr. began exploring the causes of "drunkenness" in deep-sea
divers. He tested the effects of varying the breathing mixtures on his subjects, and discovered that this caused the divers
to perceive a change in depth. From his results, he deduced that xenon gas could serve as an anesthetic. Although Lazharev, in Russia, apparently studied xenon anesthesia in 1941, the first published report confirming xenon anesthesia was in 1946 by J.
H. Lawrence, who experimented on mice. Xenon was first used as a surgical anesthetic in 1951 by Stuart C. Cullen, who successfully
operated on two patients.[24]
In 1960 physicist John H. Reynolds discovered that certain meteorites contained an isotopic anomaly in the form of an overabundance of xenon-129. He inferred
that this was a decay product of radioactive iodine-129. This isotope is produced slowly by cosmic ray spallation and nuclear fission, but is produced in quantity only in supernova explosions. As the half-life of 129I
is comparatively short on a cosmological time scale, only 16 million years, this demonstrated that only a short time had passed
between the supernova and the time the meteorites had solidified and trapped the 129I. These two events (supernova
and solidification of gas cloud) were inferred to have happened during the early history of the Solar System, as the 129I isotope was likely generated before the Solar System was
formed, but not long before, and seeded the solar gas cloud isotopes with isotopes from a second source. This supernova source
may also have caused collapse of the solar gas cloud. [25][26]
Xenon and the other noble gases were for a long time considered to be completely chemically
inert and not able to form compounds. However, while teaching at the University of British Columbia, Neil Bartlett discovered that the gas platinum hexafluoride (PtF6) was a powerful oxidizing agent that could oxidize oxygen gas (O2) to form dioxygenyl hexafluoroplatinate (O2+[PtF6]−).[27] Since O2 and xenon have almost the same first ionization potential, Bartlett realized that platinum hexafluoride might also be able to oxidize xenon. On
March 23, 1962, he mixed the two gases and produced the first known compound of a noble gas, xenon hexafluoroplatinate.[28][7] Bartlett thought its composition to be Xe+[PtF6]−, although later work has revealed
that it was probably a mixture of various xenon-containing salts.[29][30][31] Since then, many other xenon compounds have been discovered,[32] and some compounds of the noble gases argon, krypton, and radon have been identified, including argon fluorohydride (HArF),[33] krypton difluoride (KrF2),[34][35] and radon fluoride.[36]
Occurrence
Xenon is a trace gas in Earth's atmosphere, occurring at 0.087±0.001 parts per million (μL/L),[37] and is also found in gases emitted from some mineral springs. Some radioactive species of xenon, for example, 133Xe and 135Xe,
are produced by neutron irradiation of fissionable material within nuclear reactors.[5]
Xenon is obtained commercially as a byproduct of the separation of air into oxygen and nitrogen. After this separation, generally performed by fractional distillation in a double-column plant, the liquid oxygen produced will contain small quantities of krypton and xenon. By additional fractional
distillation steps, the liquid oxygen may be enriched to contain 0.1–0.2% of a krypton/xenon mixture, which is extracted
either via adsorption onto silica gel or by distillation. Finally, the krypton/xenon mixture may be separated into krypton and xenon via distillation.[38][39] Extraction of a liter of xenon from the atmosphere requires 220 watt-hours of energy.[40] Worldwide production of xenon in 1998 was estimated at 5,000–7,000 m3.[41] Due to its low abundance, xenon is much more expensive than the lighter noble gases—approximate prices for the
purchase of small quantities in Europe in 1999 were 10 €/L for xenon, 1 €/L for krypton, and 0.20 €/L for neon.[41]
Xenon is relatively rare in the Sun's atmosphere, on Earth, and in asteroids and comets. The atmosphere of Mars shows a xenon abundance similar to that of Earth: 0.08 parts per million,[42] however Mars shows a higher proportion of 129Xe than the Earth or the Sun. As this isotope is generated
by radioactive decay, the result may indicate that Mars lost most of its primordial atmosphere, possibly within the first
100 million years after the planet was formed.[43][44] By contrast, the planet Jupiter has an unusually high abundance of xenon in its atmosphere; about 2.6 times as much as
the Sun.[45] This high abundance remains unexplained and may have been caused by an early and rapid buildup of planetesimals—small, subplanetary bodies—before the presolar disk began to heat up.[46] (Otherwise, xenon would not have been trapped in the planetesimal ices.) Within the Solar System, the nucleon fraction for all isotopes of xenon is 1.56 × 10-8, or one part in 64 million
of the total mass.[47] The problem of the low terrestrial xenon may potentially be explained by covalent bonding of xenon to oxygen within quartz, hence reducing the outgassing of xenon into the atmosphere.[48]
Unlike the lower mass noble gases, the normal stellar nucleosynthesis process inside a star does not form xenon. Elements more massive than iron-56 have a net energy cost to produce through fusion, so there is no energy gain for a star
to create xenon.[49] Instead, many isotopes of xenon are formed during supernova explosions.[50]
SOPHIA OF WISDOM III - ANGELS & DEMONS 2
LIBRARY OF SOPHIA OF WISDOM III
THE SOPHIA OF ALL THE SOPHIA OF WISDOMS
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SOPHIA OF WISDOM III - ANGELS &
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LIBRARY OF SOPHIA OF WISDOM III
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