Xenon is the chemical element with atomic number 54 and element symbol Xe. The element is a noble gas, so it is inert, colorless, odorless, flavorless, and non-toxic. Xenon is best known for its use in high-power lamps. Here is a collection of interesting xenon facts, along with the history of its discovery, uses, and sources.
Xenon Element Facts
Atomic Number: 54
Element Symbol: Xe
Appearance: Colorless gas
Group: Group 18 (noble gas)
Period: Period 5
Element Family: Noble gas
Atomic Mass: 131.293(6)
Electron Configuration: [Kr] 4d10 5s2 5p6
Electrons per Shell: 2, 8, 18, 18, 8
Discovery: William Ramsay and Morris Travers (1898)
Name Origin: Greek xenos, meaning stranger
History of Discovery
Scottish chemistry William Ramsay and English chemist Morris Travers isolated and discovered xenon in September 1898. They had already discovered the noble gases krypton and neon, using a liquid air machine gifted to them by industrialist Ludwig Mond. The obtained xenon by evaporating liquefied air and examining the residue. When they placed the gas in a vacuum tube, the observed its stunning blue glow. Ramsay proposed the new element’s name, from the Greek word “xenos,” meaning “strange.” Ramsay described xenon as a stranger in the sample of liquefied air.
Natural xenon consists of seven stable isotopes: Xe-126, Xe-128, Xe-129, Xe-130, Xe-131, Xe-132, and Xe-134. Although Xe-126 and Xe-134 theoretically undergo double beta decay, it has never been observed. Over 40 radioactive isotopes have been described. The longest-lived radioisotope is Xe-124, which has a half-life of 1.8 × 1022 yr.
Biological Role and Toxicity
Elemental xenon is non-toxic and serves no biological role. However, xenon is soluble in blood and crosses the blood-brain barrier, acting as an anesthetic. It’s possible to be asphyxiated by xenon, since it is heavier than oxygen, although it’s possible to breath a xenon-oxygen mixture. Xenon compounds, especially oxygen-xenon compounds, may be toxic and explosive.
Sources of Xenon
Xenon is a rare gas in the Earth’s atmosphere, present at a concentration of about 1 part per 11.5 million (0.087 parts per million). Although it’s rare, the best source of the element is extraction from liquid air. Xenon also occurs in the Martian atmosphere at about the same concentration. The element has been found in the Sun, meteorites, and Jupiter. For a long time, scientists thought the atmosphere was the only source of xenon on Earth, but the concentration in air didn’t match the amount predicted for the planet. Researchers discovered the gas is emitted by some mineral springs, so xenon also exists within the Earth. It may be the so-called “missing xenon” may be found in the Earth’s core, possibly bonded to iron and nickel.
Xenon is used in gas-discharge lamps, including photography flashes, automobile headlamps, strobes, and bactericidal lamps (because the spectrum includes a strong ultraviolet component). It’s used in movie project lamps and high-end flashlights because its spectrum is close to that of natural sunlight. It’s used in night vision system because of its near-infrared emission. A mixture of xenon and neon is a component of plasma displays.
The first excimer laser used a xenon dimer (Xe2). Xenon is a popular element for several types of laser.
In medicine, xenon is a general anesthetic, neuroprotectant, and cardioprotectant. Is is used in sports doping to increase red blood cell production and performance. The isotope Xe-133 is used in single photon emission computer tomography, while Xe-129 is used as a contrast agent for magnetic resonance imaging (MRI). Xenon chloride excimer lasers are used for some dermatology procedures.
Xenon is also used in nuclear magnetic resonance (NMR) to aid surface characterization. It is used in bubble chambers, calorimeters, and as an ion propulsion propellant.
Noble gases are relatively inert, but they do form some compounds. Xenon hexafluoroplatinate was the first noble gas compound ever synthesized. Over 80 xenon compounds are known, including chlorides, fluorides, oxides, nitrates, and metal complexes.
Density (at STP): 5.894 g/L
Melting Point: 161.40 K (−111.75 °C, −169.15 °F)
Boiling Point: 165.051 K (−108.099 °C, −162.578 °F)
Triple Point: 161.405 K, 81.77 kPa
Critical Point: 289.733 K, 5.842 MPa
State at 20ºC: gas
Heat of Fusion: 2.27 kJ/mol
Heat of Vaporization: 12.64 kJ/mol
Molar Heat Capacity: 21.01 J/(mol·K)
Thermal Conductivity: 5.65×10−3 W/(m·K)
Crystal Structure: face-centered cubic (fcc)
Magnetic Ordering: diamagnetic
Covalent Radius: 140±9 pm
Van der Waals Radius: 216 pm
Electronegativity: Pauling scale: 2.6
1st Ionization Energy: 1170.4 kJ/mol
2nd Ionization Energy: 046.4 kJ/mol
3rd Ionization Energy: 3099.4 kJ/mol
Common Oxidation States: Usually 0, but can be +1, +2, +4, +6, +8
Fun Xenon Facts
- Because xenon is more dense than air, it can be used to produce a deep-sounding voice (the opposite of helium). However, it’s not often used for this purpose because xenon is an anesthetic.
- Similarly, if you fill a balloon with xenon gas, it will sink to the floor.
- While xenon gas, liquid, and solid are colorless, there is a metallic solid state of the element that is sky blue.
- Nuclear fission (like from the Fukushima reactor) can produce the radioisotope iodine-135. Iodine-135 undergoes beta decay to produce the radioisotope xenon-135.
- Bartlett, Neil (2003). “The Noble Gases.” Chemical & Engineering News. American Chemical Society. 81 (36): 32–34. doi:10.1021/cen-v081n036.p032
- Brock, David S.; Schrobilgen (2011). “Synthesis of the Missing Oxide of Xenon, XeO2, and Its Implications for Earth’s Missing Xenon.” J. Am. Chem. Soc. 2011, 133, 16, 6265–6269. doi:10.1021/ja110618g
- Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 0-08-037941-9.
- Meija, J.; et al. (2016). “Atomic Weights of the Elements 2013 (IUPAC Technical Report)”. Pure and Applied Chemistry. 88 (3): 265–91. doi:10.1515/pac-2015-0305