The X-treme Element Xenon

xenon element lamp

Introduction to Xenon

The element xenon is a colorless noble gas. Xenon is primarily known for its remarkable reactivity among noble gases and its characteristic sky blue light emission. Due to these properties, xenon has many important uses today, including in gas-discharge lamps, medical anesthesia, and chemical research.

10 Fun Facts about Xenon

  • The World Anti-Doping Agency considers xenon a prohibited substance. Inhaling xenon activates a biochemical chain reaction which results in elevated red blood cells, which increases athletic performance.
  • Xenon is commonly used as a propellant in ion propulsion engines for spacecraft. NASA’s Dawn Spacecraft, launched in 2007 to study the asteroid belt, uses xenon ion engines.
  • The element’s name comes from the Greek word “xenos”, meaning stranger.
  • Though most commonly found in the gas phase, chemists have solidified xenon using hundreds of kilobars of pressure. The resulting crystal has a faint sky-blue hue.
  • The isotopes xenon-133 and xenon-135 are common uranium and plutonium fission products. As a result, officials use the detection of these xenon isotopes as prove compliance with nuclear test ban treaties.
  • Xenon can form structures called endohedral fullerene compounds. These involve an atom of xenon trapped in a spherical structure of 20 or more carbons.
  • Though much less commonly practiced than the 1H and 13C varieties, 129Xe Nuclear Magnetic Resonance spectroscopy has many important uses in chemical research.
  • Movie projectors primarily use xenon-containing short-arc lamps, including in IMAX projection systems.
  • Many mineral springs emit xenon, among other gases such as hydrogen sulfide and carbon dioxide.
  • The xenon dimer (Xe2), in the form of a liquid, was involved in the first excimer (“excited dimer”) laser in 1971. Later versions of excimer lasers involved xenon halides, such as XeBr.

Xenon in the Periodic Table

Xenon has the atomic symbol Xe with an atomic number of 54. It locates in the p-block of the periodic table, preceded by iodine and succeeded by cesium. Xenon occupies the fifth element in the noble gas group of the periodic table. Xenon has an electron configuration of [Kr]4d105s25p6, or simply [Xe]. Additionally, the element has an electronegativity of 2.60 on the Pauling scale. 

Xenon’s Application in Today’s World

What is xenon element used for?

Xenon has many important modern uses, both in research and industry. In general, however, the modern world predominantly depends on xenon for two uses: gas-discharge lamps and anesthetics.

Xenon in Gas-Discharge Lamps

Due to emitting light in the visible spectrum, xenon has a lot of use in gas-discharge lamps. These lamps involve a glass bulb filled with gas, along with two electrodes: the anode and cathode. The electric flow between the electrodes displaces electrons from the valence shell of xenon molecules, which become high-energy cations. Chemists call these ionized gas particles “plasma”.

These cations then collide with neutral xenons, resulting in an electron exchange that neutralizes the cations. This neutralization returns the ionized xenon to its low-energy ground state, with the loss in energy emitted as a photon. The light emanating from the lamp is the total of these photons from deionized xenons.

While other noble gases can also perform this gas-discharge light-producing reaction, such as neon or argon, xenon has particular advantages. Of the stable noble gases, xenon has the lowest ionization energy, which means that it most readily ionizes and produces light. Additionally, xenon has the lowest thermal conductivity, which means that the lamp emits less heat while in operation, saving energy.

lamp with xenon element

Xenon as an Anesthetic

In 1939, the anesthetic qualities of xenon were discovered by coincidence by American physician Albert R. Behnke. Behnke was researching the effects of breathing different mixes of gases. He noted xenon affected subjects’ depth perception and concluded that it must have anesthetic qualities. Experiments with mice confirmed the existence of xenon anesthesia, which began use in surgeries starting in the 1950s.

Despite its broadly unreactive chemistry, like other noble gases, xenon does interact with cellular receptors to produce an anesthetic effect. Specifically, xenon inhibits N-methyl-D-aspartate receptors, similar to ketamine or nitrous oxide. In addition, xenon reduces the activity of neuronal ATPase Ca2+ pumps, which decreases sensitivity. This results in both hypnotic and analgesic behavioral effects, called “dissociative anesthesia” by anesthesiologists. 

However, unlike ketamine and nitrous oxide, xenon does not harm neurons over long periods of exposure. Xenon also appears to not interfere with the cardiovascular system, which is very important during surgery.

Between its effectiveness and lack of serious side effects, relative to similar anesthetics, many anesthesiologists have declared xenon as the “ideal anesthetic”.

Where is xenon element found?

Xenon occurs naturally in the Earth’s atmosphere at a concentration of 1 part per 11.5 million. Elsewhere in the solar system, xenon tends to be similarly scarce, though Jupiter has a particularly high abundance at a ratio of 1.68 X 10-10 xenons per hydrogen

Additionally, commercial nuclear fission of elements such as uranium, plutonium, and thorium frequently produces xenon as a byproduct. However, many of the resulting xenon isotopes are unstable and quickly beta decay into cesium.

When and How was the Element Xenon Discovered?

Xenon, like many noble gases, remained undiscovered for much longer than most naturally occurring Earth elements. This is mainly due to its lack of chemical reactivity, which produced little evidence of its existence to chemists.

However, in 1898, British chemists William Ramsay and Morris Travers discovered xenon while studying the composition of air. Specifically, the pair liquified a sample of air and performed fractional distillation. After the most abundant atmospheric gases were separated from the sample, like oxygen and nitrogen, a peculiar residue of liquid air remained. This residue turned out to involve many previously undiscovered noble gases. Thus, by continuing the distillation, Ramsay and Travers eventually discovered xenon, shortly following the discovery of krypton and neon.

Xenon Chemistry – Compounds, Reactions, Oxidation States

Xenon Compounds and Reactions

Chemists have discovered many different types of xenon compounds generally split into four groups:

  • Xenon-Halides: XeF2, XeF4, XeF6, XeCl2, XeCl4
  • Xenon-Oxides: XeO2, XeO3, XeO4
  • Xenon-Oxohalides: XeOF2, XeOF4, XeO2F2, XeO3F2
  • Organoxenon Compounds: (C6F5)2Xe, C7F5XeF

Other, more exotic, xenon-containing compounds have been discovered. One interesting example includes tetraxenongold (II) ([Xe4Au2+]), which involves xenon acting as a ligand in an ion complex.

tetraxenonogold, with xenon element as a ligand

Despite the general unreactivity of noble gases, chemists have observed xenon performing many different chemical reactions.

The first reaction involving gaseous xenon, discovered in 1962, produced a salt from reacting with a platinum fluoride ion:

Xe + PtF6 → Xe(PtF6)

Xenon can also directly react with diatomic halides to form xenon halides. Such reactions require high temperatures (400°C):

Xe + 2F2 → XeF4

Xenon halides can subsequently react with oxygen-containing species to yield xenon oxides or oxohalides. They can even react with water through a hydrolysis reaction:

XeF6 + 3H2O → XeO3 + 6HF

In organic synthesis, xenon fluorides provide a very powerful fluorinating agent, making them useful in synthesis chains. Xenon fluorides can even participate in electrophilic aromatic substitutions:

xenon element diflouride electrophilic aromatic substitution

Isolation of Xenon Element

Just like Ramsay and Travers in 1898, chemists generally isolate xenon by distilling liquid air. After separating the sample into oxygen and nitrogen, chemists then perform fractional distillation on the resulting liquid oxygen. Importantly, a silica gel adsorbent is used with the distillation to separate the krypton and xenon from the oxygen. One final distillation consequently separates the krypton from the xenon.

Xenon Oxidation States

Due to the characteristic unreactivity of noble gases, xenon overwhelmingly exhibits the neutral oxidation state (0). However, when it does participate in chemical reactions, xenon has one of four known oxidations states:

  • Xe(II): Xe2+, XeF2, XeCl2, XeH+
  • Xe(IV): Xe4+, XeF4, XeO2, XeOF2
  • Xe(VI): Xe6+, XeF6, XeO3
  • Xe(VIII): Xe8+, XeO4

Properties of Xenon Element

  • Atomic Symbol: Xe
  • Melting point: 161.4K; -111.8°C; -169.2°F
  • Boiling point: 165.0K; -108.1°C; 162.6°F
  • Density at STP: 5.894 g/L
  • Atomic weight: 131.293
  • Atomic number: 54
  • Electronegativity: 2.60
  • Molar heat capacity: 21.01 J/(mol*K)
  • Classification: Noble Gas
  • Natural abundance in the Earth’s atmosphere: 0.086 ppm
  • Electron shell configuration: [Kr]4d105s25p6
  • Stable Isotopes: 128, 129, 130, 131, 132
  • Found naturally in the minerals: N/A
  • Toxicity: Non-Toxic

Where can I buy xenon?

Small vials of xenon element for chemistry collections are sold by many online vendors, including Amazon. Larger quantities of xenon for commercial gas lamp production or research are also sold by specialty gas suppliers. For these larger orders, vendors often sell pure xenon gas for $10-$15 per liter.