Xenon (Xe)
Noble gas
Xenon is a heavy, rare noble gas that surprised chemists in 1962 by forming genuine compounds — the first “inert” gas ever to react. It shines blue-white in car headlights and anaesthetises patients in some operating theatres.
Position on the periodic table
Atomic properties
| Atomic number | 54 |
|---|---|
| Atomic mass | 131.294 amu |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 |
| Noble gas shorthand | [Kr] 4d10 5s2 5p6 |
| Electrons per shell | 2, 8, 18, 18, 8 |
| Valence electrons (outer shell) | 8 |
| Common oxidation states | +2, +4, +6 |
| Electronegativity (Pauling) | 2.6 |
| Covalent radius (approx.) | 140 pm |
| First ionization energy | 1170 kJ/mol |
| Electron affinity | -77 kJ/mol |
Physical properties
| State at 25 °C | Gas |
|---|---|
| Density | 5.894 g/L |
| Melting point | -111.75 °C (161.4 K) |
| Boiling point | -108.1 °C (165.05 K) |
| Appearance | colorless gas, exhibiting a blue glow when placed in a high voltage electric field |
| Radioactive | No |
| Origin | Occurs naturally |
Electron configuration of xenon
Xenon's ground-state electron configuration is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6, usually shortened to [Kr] 4d10 5s2 5p6. Its electrons occupy 5 shells (2, 8, 18, 18, 8), placing it in period 5 of the p-block. The 8 outer-shell electrons drive its bonding behaviour. Explore it interactively in the electron configuration calculator.
Uses of xenon
- High-intensity lamps and cinema projectors
- Ion propulsion for spacecraft
- Medical anaesthesia (specialist use)
- Dark-matter detection experiments
Biological role: None; acts as an anaesthetic gas at high concentration.
Occurrence: Only ~0.09 parts per million of the atmosphere — extracted from liquefied air.
Common compounds of xenon
XeF2
Xenon difluoride
XeF4
Xenon tetrafluoride
History and discovery
Discovered: 1898 — William Ramsay. Name origin: From Greek xenos, meaning stranger.
William Ramsay and Morris Travers found xenon in 1898 in the last, heaviest fraction of liquefied air.
Safety notes
Inert and non-toxic (an asphyxiant in bulk); its fluorides are reactive lab-only compounds.
Educational context only — always follow your school's laboratory rules and never handle chemicals without proper supervision. See our disclaimer.
Practice questions
Quick practice: Xenon
1. What is the chemical symbol of Xenon?
2. What is the atomic number of Xenon?
3. Which category does Xenon belong to?
4. What is the state of Xenon at room temperature?
5. Which period of the periodic table is Xenon in?
Xenon FAQs
What is the atomic number of xenon?
Xenon's atomic number is 54 — every xenon atom has 54 protons in its nucleus.
What is the symbol for xenon?
Xe. From Greek xenos, meaning stranger.
Is xenon a metal, nonmetal, or metalloid?
Xenon is classified as a noble gas.
What state is xenon at room temperature?
At about 25 °C, xenon is a gas. It melts at -111.75 °C.
How many valence electrons does xenon have?
Xenon has 8 electrons in its outer shell (shell pattern: 2, 8, 18, 18, 8).
What is xenon used for?
Key uses include: high-intensity lamps and cinema projectors; ion propulsion for spacecraft; medical anaesthesia (specialist use).
Related elements
Keep working with this element
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