Xenon
[Kr] 4d¹⁰ 5s² 5p⁶ · 2 · 8 · 18 · 18 · 8
The heaviest stable noble gas and the first to be coaxed into a chemical compound, which demolished the dogma that group 18 was wholly inert. Xenon is also an anaesthetic.
3D model
Bohr model: nucleus and electron shells from the real configuration. Valence electrons are highlighted.
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Atomic properties
- Atomic number
- 54
- Atomic mass
- 131.293 а.е.м.
- Electron configuration
- [Kr] 4d¹⁰ 5s² 5p⁶
- Electrons per shell
- 2 · 8 · 18 · 18 · 8
- Block
- p-block
- Group
- Noble gases
- Period
- 5
- Electronegativity (Pauling)
- 2.6
- Electronegativity (Allen)
- 2.58
- Atomic radius
- 108 pm
- Covalent radius
- 140 pm
- Van der Waals radius
- 216 pm
- Ionisation energy 1
- 1 170.4 kJ/mol
- Ionisation energy 2
- 2 046.4 kJ/mol
- Ionisation energy 3
- 3 099.4 kJ/mol
- Electron affinity
- 0 kJ/mol
- Common oxidation states
- 0
- Oxidation states
- 0, +2, +4, +6, +8
Physical properties
- State at 25 °C
- gas
- Density
- 0.00589 g/cm³
- Melting point
- 161.4 K · -111.8 °C
- Boiling point
- 165.05 K · -108.1 °C
- Speed of sound
- 1 090 m/s
Thermal properties
- Heat of fusion
- 2.27 kJ/mol
- Heat of vaporisation
- 12.64 kJ/mol
- Specific heat capacity
- 0.158 J/(g·K)
- Thermal conductivity
- 0.00565 W/(m·K)
Mechanical properties
- Young's modulus
- no data
- Shear modulus
- no data
- Bulk modulus
- no data
- Poisson ratio
- no data
- Mohs hardness
- no data
- Brinell hardness
- no data
Electrical and magnetic properties
- Electrical resistivity
- no data
- Magnetic ordering
- diamagnetic
- Curie point
- no data
- Néel point
- no data
- Superconducting point
- no data
Crystal structure
- Crystal structure
- face-centred cubic (fcc)
- Lattice constants
- a = 619.7 pm
Abundance
- In the crust
- 3·10⁻⁵ mg/kg
- In the ocean
- 5·10⁻⁵ mg/L
- In the universe
- 10 mg/kg
- In the human body
- 0 mg/kg
Isotopes
| Isotope | Abundance | Half-life | Decay mode |
|---|---|---|---|
| 124Xe | 0.095 % | stable | — |
| 126Xe | 0.089 % | stable | — |
| 128Xe | 1.91 % | stable | — |
| 129Xe | 26.401 % | stable | — |
| 130Xe | 4.071 % | stable | — |
| 131Xe | 21.232 % | stable | — |
| 132Xe | 26.909 % | stable | — |
| 134Xe | 10.436 % | stable | — |
| 136Xe | 8.857 % | stable | — |
Nine stable isotopes, sharing with tin the record for natural nuclides. Xenon-136 is used in searches for neutrinoless double beta decay.
Discovery
- Year of discovery
- 1898
- Discovered by
- William Ramsay and Morris Travers
- Where
- England
- Origin of the name
- from Greek xenos (stranger)
History
Ramsay and Travers found xenon in July 1898 in the residue from distilling krypton. In 1962 Neil Bartlett made xenon hexafluoroplatinate, the first noble gas compound ever.
Where it occurs
0.087 ppm of the atmosphere — the rarest of the non-radioactive noble gases.
How it is produced
At the last stage of cryogenic air separation. At one part in ten million, xenon is extraordinarily expensive.
Role in living things
No biological role, but xenon binds NMDA receptors and produces anaesthesia — a rare case of an inert gas with a physiological action.
Safety
Non-toxic; at high concentrations it anaesthetises and displaces oxygen. WADA lists it as a prohibited substance for stimulating erythropoietin production.
Uses
- Ion thrusters on spacecraft — xenon is heavy and easily ionised
- Xenon arc lamps: a near-solar spectrum for cinema projectors and car headlights
- General anaesthesia: xenon has almost no side effects and an almost prohibitive price
- Liquid xenon detectors for dark matter and double beta decay
Curiosities
- The first noble gas compound, made in 1962, overturned the textbooks and opened a field of chemistry.
- The Dawn probe's xenon ion thruster ran for more than 50 000 hours.
- Xenon is the only anaesthetic that does not depress cardiac function.
- The largest dark matter detectors are multi-tonne tanks of liquid xenon.