Xenon was discovered in 1898 and is classified as a noble gas. It emits blue light when subjected to electrical discharge. Most commonly, xenon is used in flash lights. Some compounds of xenon are toxic due to its oxidizing property.
History and Discovery
Xenon was discovered in 1898 by chemist William Ramsay and Morris Travers. They already discovered neon, krypton and argon from liquid air so that wasn’t their first discovery. This discovery came when Ludwig Mond gifted the team a new liquid air machine. They extracted more krypton from the new machine, repeatedly distilled the krypton and isolated heavier gas. However, during extraction of krypton they examined a novel that gas in the vacuum tube that showed beautiful blue glow. They categorized the new gas as inert and Ramsay suggested the name xenon. The word xenon has been derived from Greek word xenos that means stranger. In 1920, Ramsay estimated its occurrence in the earth atmosphere which was about one part in 20 million [1]. In 1962, Neil Barlett proposed that xenon was not inert but react with other compounds and carried out many reactions [2].
Xenon
| Periodic Table Classification | Group 18 Period 5 |
|---|---|
| State at 20C | Gas |
| Color | Colorless gas, exhibiting a blue glow when placed in an electric field |
| Electron Configuration | [Kr] 4d10 5s2 5p6 |
| Electron Number | 54 |
| Proton Number | 54 |
| Electron Shell | 2, 8, 18, 18, 8 |
| Density | 5.90 g.cm-3 at 20°C |
| Atomic number | 54 |
| Atomic Mass | 131.29 g.mol -1 |
| Electronegativity according to Pauling | 2.60 |
Occurrence
Xenon is present in the Earth crust in trace amounts. It is present on earth is approximately 1 part per million. Xenon is rare in the earth’s atmosphere, Sun, asteroids and comets. Its abundance is much higher on the planet Jupiter and is about 2.6 times that of the sun. It is also present in the component of gases which are emitted from some mineral springs. Commercially, xenon is produced as a by-product during the separation of air into oxygen and nitrogen.
Physical Characteristics
Xenon is colorless, odorless and heavy noble gas. Its chemical symbol is Xe. Xenon atomic number is 54 and atomic weight is 131.29g/mol. Xenon is very dense in nature. It has a density of 5.761 kg/m3 which is about 4.5 times the density of the earth’s atmosphere at sea level. Its melting point is -111.75oC and boiling point is -108.099oC. It belongs to the group zero-valence called noble or inert because its outer most shell has eight electrons.
Chemical Characteristics
Xenon is chemically unreactive gas but it can carry out few chemical reaction. For instance, the formation of xenon hexafluoro-platinate which is categorized as the first noble gas compound. Due to its high atomic volume, it is considered as an efficient solvent that easily dissolve hydrocarbons, biological molecules and water. Xenon in solid form changes its shape from face centered cubic to hexagonal close packed crystal under pressure and then it acquires its metallic form. When metallized it appears sky blue in color because it absorbs red light and transmits others. All compounds of xenon contain electronegative elements, fluorine or oxygen. Xenon forms fluorides: XeF2, XeF4 and XeF6, and xenon fluorides behave as both donor and acceptor and form salts. Xenon does not react directly with oxygen. However, XeO3 is formed by hydrolysis of XeF6. Xenon trioxide (XeO3), Xenon tetroxide (XeO4) and xenon dioxide (XeO2) oxides are known. Xenon also react with less electronegative compounds like carbon and forms different compounds [3].
Significance and Uses
- Xenon is used in flash lamps which are used in photographic flashes.
- Xenon is also used as general anesthetic.
- Xenon is also used in stroboscopic lamp, highly sensitive arc lamps and bactericidal lamps.
- Xenon dimer molecule (Xe2) is used in first excimer laser (ultraviolet laser) as lasing medium.
- Xenon is used in search of hypothetical weakly interacting massive particles.
- Several satellites use xenon ion propulsion system to keep them in orbit and in some other space craft.
- Xenon is widely used in the preparation of 5-fluorouracil, a drug used to treat certain cancer.
- Xenon produced blue glow during electrical discharge, so it is widely used in headlights.
- It is used for filling television and radio tubes.
- Xenon is used in road signs as it provides better illumination than conventional lights.
- Xenon is used to carry out robust cardio-protection (preservation of heart by controlling myocardial damage) and neuroprtotection (preservation of neuronal structure) through variety of mechanism.
- Inhalation of xenon/oxygen mixture activate production of transcription factor, which is used as metabolism booster.
- Liquid xenon is used in calorimeters which measure gamma rays.
Health effects
Prolonged inhalation of xenon can lead to dizziness, nausea, vomiting and sometime cause death. It is chemically inert, so it does not have variety of toxic and hazardous compounds.
Isotopes of Xenon
Xenon has eight stable isotopes. More the forty unstable are also present in which longest lived isotope is 136Xe has half- life of 2.11 x 1021 years. 129Xe has half-life of 16 million years.
REFERENCES
[1]. Ramsay, William (1902). “An Attempt to Estimate the Relative Amounts of Krypton and of Xenon in Atmospheric Air”. Proceedings of the Royal Society of London. 71(467–476): 421–426.
[2]. https://www.livescience.com/37504-facts-about-xenon.html
[3]. https://en.wikipedia.org/wiki/Xenon