ELEMENTLE

Element 54 · Noble Gas

Xenon

Period 5 · Group 18

Xenon is a chemical element with symbol Xe and atomic number 54. It is a colorless, dense, odorless noble gas, that occurs in the Earth's atmosphere in trace amounts. Although generally unreactive, xenon can undergo a few chemical reactions such as the formation of xenon hexafluoroplatinate, the first noble gas compound to be synthesized.

Three reasons Xenon stands out

  1. 1

    Used in light bulbs, known for its blue glow.

  2. 2

    It is used as a propellant in ion-drive spacecraft thrusters because its heavy atoms produce efficient thrust.

  3. 3

    In 1962 it became the first noble gas ever shown to form a true chemical compound, overturning a long-held scientific belief.

The noble gas that broke the rules

Xenon’s heavy atoms are polarizable enough to form genuine compounds, overturning the old belief that noble gases were completely inert. It produces bright flashes in lamps, works as an anesthetic, and propels spacecraft in ion engines. Xenon is effective precisely because it is heavy and chemically clean.

Xenon at a glance
Atomic number / protons54
SymbolXe
Family (Elementle)Noble Gas
Classification (PubChem)Noble gas
Period5
Group18
Atomic mass (u)131.29
Standard stateGas
Electron configuration[Kr]5s2 4d10 5p6
Reported oxidation states0
Electronegativity (Pauling)2.6
Atomic radius (pm)216
First ionization energy (eV)12.130
Electron affinity (eV)Not available
Density (g/cm³)0.005887
Melting point161.36 K (-111.79 °C)
Boiling point165.03 K (-108.12 °C)
Discovery (PubChem)1898

Values are reference data, not a specification for every temperature, pressure, or allotrope. Unknown properties are left unavailable. Superheavy-element predictions remain uncertain.

Sources & further reading

PubChem: Xenon · Xenon on Wikipedia

The introduction and original editorial story are adapted from Wikipedia contributors via Periodic-Table-JSON. Element descriptions and their adaptations are available under CC BY-SA 3.0. Numerical attributes use the PubChem periodic-table dataset, retrieved September 22, 2026.