Xenon
Atomic Data
| Atomic Number | 54 |
| Symbol | Xe |
| Atomic Weight | 131.29 u |
| Density (STP) | 5.894 g/L |
| Melting Point | −111.75 °C (161.4 K) |
| Boiling Point | −108.12 °C (165.03 K) |
| Electronegativity | : |
| Electron Config. | 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 |
| Oxidation States | 0, +2, +4, +6, +8 |
| Phase at STP | Gas |
| Category | Noble Gas |
| Period / Group | 5 / 18 |
| CAS Number | 7440-63-3 |
Electron Configuration
[Kr] 4d10 5s2 5p6
| Shell | n | Subshell | Electrons | Cumulative |
|---|---|---|---|---|
| K | 1 | 1s | 2 | 2 |
| L | 2 | 2s | 2 | 4 |
| L | 2 | 2p | 6 | 10 |
| M | 3 | 3s | 2 | 12 |
| M | 3 | 3p | 6 | 18 |
| M | 3 | 3d | 10 | 28 |
| N | 4 | 4s | 2 | 30 |
| N | 4 | 4p | 6 | 36 |
| N | 4 | 4d | 10 | 46 |
| O | 5 | 5s | 2 | 48 |
| O | 5 | 5p | 6 | 54 |
| Total | 54 | 54 | ||
Isotopes of Xenon
Xenon has nine naturally occurring stable isotopes. The most abundant is ¹³²Xe, comprising 26.909% of all naturally occurring Xenon.
| Isotope | Symbol | Protons | Neutrons | Abundance | Stability |
|---|---|---|---|---|---|
| Xenon-124 | ¹²⁴Xe | 54 | 70 | 0.095 | Stable |
| Xenon-126 | ¹²⁶Xe | 54 | 72 | 0.089 | Stable |
| Xenon-128 | ¹²⁸Xe | 54 | 74 | 1.91 | Stable |
| Xenon-129 | ¹²⁹Xe | 54 | 75 | 26.401 | Stable |
| Xenon-130 | ¹³⁰Xe | 54 | 76 | 4.071 | Stable |
| Xenon-131 | ¹³¹Xe | 54 | 77 | 21.232 | Stable |
| Xenon-132 | ¹³²Xe | 54 | 78 | 26.909 | Stable |
| Xenon-134 | ¹³⁴Xe | 54 | 80 | 10.436 | Stable |
| Xenon-136 | ¹³⁶Xe | 54 | 82 | 8.857 | Stable |
Abundance & Occurrence
Xenon is present in Earth's crust at approximately 3e-05 ppm by mass and at approximately 8 ppm by mass throughout the universe.
Earth's Crust (ppm by mass)
Universe (ppm by mass)
Discovery & History
Read more about the discovery of the periodic table of elements →
Safety & Handling
- Asphyxiation: Xenon is a colourless, odourless inert gas; it is denser than air and can displace oxygen in enclosed or low-lying spaces, causing unconsciousness without warning.
- Pressurised cylinders: Xenon is stored under high pressure; cylinders must be secured upright and kept away from heat sources.
- Anaesthetic properties: Xenon is a potent anaesthetic at concentrations above ~65%; unintended high concentrations from cylinder leaks in enclosed spaces can cause rapid incapacitation before an individual can self-rescue.
- Xenon-133: radiation: Xe-133 (t½ = 5.2 days, beta/gamma) is used in lung ventilation scintigraphy; exhaled xenon from patients must be trapped or vented to prevent nuclear medicine department contamination.
Xenon in the Real World
Real-World Uses
- High-intensity discharge headlights: Xenon HID headlamps produce 2–3 times more light per watt than halogen headlights with a white light spectrum close to daylight, improving night-time driving visibility in luxury and high-performance vehicles.
- Ion thrusters for spacecraft: Xenon propellant is ionised and accelerated electrostatically in ion propulsion systems used in deep-space probes (Dawn, Hayabusa2, Starlink satellites) for fuel-efficient long-duration thrust.
- Medical anaesthesia: Xenon is an anaesthetic agent with rapid induction and recovery, minimal cardiovascular side effects, and neuroprotective properties; it is used clinically in some countries though high cost limits wide adoption.
- Excimer lasers: Xenon chloride (XeCl, 308 nm) and xenon fluoride (XeF, 351 nm) excimer lasers are used in dermatology (psoriasis and vitiligo treatment), ultraviolet photolithography, and scientific research.
- Nuclear test ban verification: Xenon isotopes produced in nuclear reactors and nuclear explosions are monitored globally as a key tool for verifying compliance with the Comprehensive Nuclear-Test-Ban Treaty.
Downloadable Resources
Free periodic table reference sheets for classrooms, study sessions, and laboratory use.
Frequently Asked Questions
What is xenon used for?
Xenon is used in high-intensity discharge lamps: HID headlights in cars and cinema projectors use xenon arc lamps for their intense, white light. Xenon is used as an anaesthetic gas in some medical settings. Ion propulsion thrusters in spacecraft (such as the Dawn and Hayabusa missions) use xenon as propellant. Xenon flash lamps are used in photography and strobe lights.
Can xenon form chemical compounds?
Yes: xenon was the first noble gas shown to form stable compounds, disproving the long-held belief that noble gases were completely chemically inert. In 1962, Neil Bartlett synthesised xenon hexafluoroplatinate. Subsequently, xenon difluoride (XeF2), xenon tetrafluoride (XeF4), and xenon hexafluoride (XeF6) were prepared. XeF2 is used as a selective fluorinating agent in organic chemistry and as an etchant in semiconductor manufacturing.
How was xenon discovered?
Xenon was discovered in 1898 by William Ramsay and Morris Travers by fractional distillation of liquid air, the same method used to discover krypton and neon the same year. They detected it spectroscopically by its distinctive bright blue glow. The name comes from the Greek 'xenos', meaning stranger or foreign, reflecting its rarity in the atmosphere (about 87 parts per billion by volume).
How do xenon ion thrusters work?
In a xenon ion thruster, xenon gas is ionised by electron bombardment in an ionisation chamber. The positive xenon ions are then accelerated to high velocities (30–90 km/s) through an electric grid. The stream of high-speed ions produces thrust by Newton's third law. While the thrust is tiny (comparable to the weight of a coin), ion thrusters operate with 10 times the fuel efficiency of chemical rockets, making them ideal for long interplanetary missions.