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= = Death and legacy = =
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Berhtwald died on 13 January 731 . An epitaph to him in verse survives , and may have been placed over his tomb , which was at Canterbury . Subsequently he was canonised with a feast day of 9 January . Little evidence of extensive cult activity exists , however , and the main evidence for his sainthood is a late medie... |
= Xenon =
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Xenon is a chemical element with symbol Xe and atomic number 54 . It is a colorless , dense , odorless noble gas , that occurs in the Earth 's atmosphere in trace amounts . Although generally unreactive , xenon can undergo a few chemical reactions such as the formation of xenon hexafluoroplatinate , the first noble ga... |
Xenon is used in flash lamps and arc lamps , and as a general anesthetic . The first excimer laser design used a xenon dimer molecule ( Xe2 ) as its lasing medium , and the earliest laser designs used xenon flash lamps as pumps . Xenon is also being used to search for hypothetical weakly interacting massive particles ... |
Naturally occurring xenon consists of eight 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 . Radioactive xenon @-@ 135 is produced by beta decay from iodine @-@ 135 ( which ... |
= = History = =
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Xenon was discovered in England by the Scottish chemist William Ramsay and English chemist Morris Travers in September 1898 , shortly after their discovery of the elements krypton and neon . They found xenon in the residue left over from evaporating components of liquid air . Ramsay suggested the name xenon for this g... |
During the 1930s , American 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 electric current through a tube filled with xenon gas . In 1934 , Edgerton was able to generat... |
In 1939 , American physician 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 coul... |
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 oxyg... |
In November 1999 IBM scientists demonstrated a technology capable of manipulating individual atoms . The program , called IBM in atoms , used a scanning tunneling microscope to arrange 35 individual xenon atoms on a substrate of chilled crystal of nickel to spell out the three letter company acronym . It was the first... |
= = Characteristics = =
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Xenon has atomic number 54 ; that is , its nucleus contains 54 protons . At standard temperature and pressure , pure xenon gas has a density of 5 @.@ 761 kg / m3 , about 4 @.@ 5 times the surface density of the Earth 's atmosphere , 1 @.@ 217 kg / m3 . As a liquid , xenon has a density of up to 3 @.@ 100 g / mL , with... |
Solid xenon changes from face @-@ centered cubic ( fcc ) to hexagonal close packed ( hcp ) crystal phase under pressure and begins to turn metallic at about 140 GPa , with no noticeable volume change in the hcp phase . It is completely metallic at 155 GPa . When metallized , xenon looks sky blue because it absorbs red... |
Liquid or solid xenon nanoparticles can be formed at room temperature by implanting Xe + ions into a solid matrix . Many solids have lattice constants smaller than solid Xe . This results in compression of the implanted Xe to pressures that may be sufficient for its liquefaction or solidification .
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Xenon is a member of the zero @-@ valence elements that are called noble or inert gases . It is inert to most common chemical reactions ( such as combustion , for example ) because the outer valence shell contains eight electrons . This produces a stable , minimum energy configuration in which the outer electrons are ... |
In a gas @-@ filled tube , xenon emits a blue or lavenderish glow when the gas is excited by electrical discharge . Xenon emits a band of emission lines that span the visual spectrum , but the most intense lines occur in the region of blue light , which produces the coloration .
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= = Occurrence and production = =
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Xenon is a trace gas in Earth 's atmosphere , occurring at 87 ± 1 parts per billion ( nL / L ) , or approximately 1 part per 11 @.@ 5 million , and is also found as a component in gases emitted from some mineral springs .
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Xenon is obtained commercially as a by @-@ product 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 distillat... |
Within the Solar System , the nucleon fraction of xenon is 1 @.@ 56 × 10 − 8 , for an abundance of approximately one part in 630 thousand of the total mass . Xenon is relatively rare in the Sun 's atmosphere , on Earth , and in asteroids and comets . The planet Jupiter has an unusually high abundance of xenon in its a... |
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 when creating xenon . Instead , xenon is formed during supernova explosions ... |
= = Isotopes and isotopic studies = =
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Naturally occurring xenon is made of eight stable isotopes , the most of any element with the exception of tin , which has ten . Xenon and tin are the only elements to have more than seven stable isotopes . The isotopes 124Xe and 134Xe are predicted to undergo double beta decay , but this has never been observed so th... |
Nuclei of two of the stable isotopes of xenon , 129Xe and 131Xe , have non @-@ zero intrinsic angular momenta ( nuclear spins , suitable for nuclear magnetic resonance ) . The nuclear spins can be aligned beyond ordinary polarization levels by means of circularly polarized light and rubidium vapor . The resulting spin... |
Because a 129Xe nucleus has a spin of 1 / 2 , and therefore a zero electric quadrupole moment , the 129Xe nucleus does not experience any quadrupolar interactions during collisions with other atoms , and thus its hyperpolarization can be maintained for long periods of time even after the laser beam has been turned off... |
Some radioactive isotopes of xenon , for example , 133Xe and 135Xe , are produced by neutron irradiation of fissionable material within nuclear reactors . 135Xe is of considerable significance in the operation of nuclear fission reactors . 135Xe has a huge cross section for thermal neutrons , 2 @.@ 6 × 106 barns , so ... |
Under adverse conditions , relatively high concentrations of radioactive xenon isotopes may be found emanating from nuclear reactors due to the release of fission products from cracked fuel rods , or fissioning of uranium in cooling water .
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Because xenon is a tracer for two parent isotopes , xenon isotope ratios in meteorites are a powerful tool for studying the formation of the solar system . The iodine @-@ xenon method of dating gives the time elapsed between nucleosynthesis and the condensation of a solid object from the solar nebula . In 1960 , physi... |
In a similar way , xenon isotopic ratios such as 129Xe / 130Xe and 136Xe / 130Xe are also a powerful tool for understanding planetary differentiation and early outgassing . For example , The atmosphere of Mars shows a xenon abundance similar to that of Earth : 0 @.@ 08 parts per million , however Mars shows a higher p... |
= = Compounds = =
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After Neil Bartlett 's discovery in 1962 that xenon can form chemical compounds , a large number of xenon compounds have been discovered and described . Almost all known xenon compounds contain the electronegative atoms fluorine or oxygen .
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= = = Halides = = =
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Three fluorides are known : XeF
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2 , XeF
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4 , and XeF
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6 . XeF is theorized to be unstable . The fluorides are the starting point for the synthesis of almost all xenon compounds .
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The solid , crystalline difluoride XeF
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2 is formed when a mixture of fluorine and xenon gases is exposed to ultraviolet light . Ordinary daylight is sufficient . Long @-@ term heating of XeF
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2 at high temperatures under an NiF
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2 catalyst yields XeF
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6 . Pyrolysis of XeF
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6 in the presence of NaF yields high @-@ purity XeF
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4 .
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The xenon fluorides behave as both fluoride acceptors and fluoride donors , forming salts that contain such cations as XeF + and Xe
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2F +
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3 , and anions such as XeF −
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5 , XeF −
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7 , and XeF2 −
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8 . The green , paramagnetic Xe +
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2 is formed by the reduction of XeF
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2 by xenon gas .
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XeF
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2 is also able to form coordination complexes with transition metal ions . Over 30 such complexes have been synthesized and characterized .
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Whereas the xenon fluorides are well @-@ characterized , the other halides are not known , the only exception being the dichloride , XeCl2 . Xenon dichloride is reported to be an endothermic , colorless , crystalline compound that decomposes into the elements at 80 ° C , formed by the high @-@ frequency irradiation of... |
2 is a real compound and not merely a van der Waals molecule consisting of weakly bound Xe atoms and Cl
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2 molecules . Theoretical calculations indicate that the linear molecule XeCl
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2 is less stable than the van der Waals complex .
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= = = Oxides and oxohalides = = =
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Three oxides of xenon are known : xenon trioxide ( XeO
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3 ) and xenon tetroxide ( XeO
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4 ) , both of which are dangerously explosive and powerful oxidizing agents , and xenon dioxide ( XeO2 ) , which was reported in 2011 with a coordination number of four . XeO2 forms when xenon tetrafluoride is poured over ice . Its crystal structure may allow it to replace silicon in silicate minerals . The XeOO + cat... |
Xenon does not react with oxygen directly ; the trioxide is formed by the hydrolysis of XeF
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6 :
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XeF
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6 + 3 H
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2O → XeO
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3 + 6 HF
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XeO
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3 is weakly acidic , dissolving in alkali to form unstable xenate salts containing the HXeO −
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4 anion . These unstable salts easily disproportionate into xenon gas and perxenate salts , containing the XeO4 −
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6 anion .
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Barium perxenate , when treated with concentrated sulfuric acid , yields gaseous xenon tetroxide :
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Ba
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2XeO
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6 + 2 H
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2SO
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4 → 2 BaSO
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4 + 2 H
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2O + XeO
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4
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