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54Xe131.29
Noble Gasesgas at STPP-block

Xenon

Group: 18Period: 5Standard Atomic Weight: 131.29 u

Why is Xenon in this position?

Understanding the scientific rationale behind Xenon's position in the periodic table:

Group Assignment
Group 18

Belongs to Group 18 because it has a full octet of 8 valence electrons (5s² 5p⁶).

Period Assignment
Period 5

Belongs to Period 5 because its valence electrons fill the n=5 shell.

Orbital Block
P-block

Belongs to the p-block because its valence subshell is a full 5p orbital.

Chemical Category
Noble Gases

Classified as a noble gas, though its large polarizable electron cloud allows it to form stable chemical bonds with fluorine and oxygen.

Atomic Structure & Bohr Shell Model

Shell Distribution: [2, 8, 18, 18, 8]

Bohr Atomic Shell Model(2, 8, 18, 18, 8)

Hover or tap any shell orbit ring to inspect electron counts and 2n² capacities.

54 Protons (p⁺)77 Neutrons (n⁰)
KShell K: Electron 1 of 2Shell K: Electron 2 of 2LShell L: Electron 1 of 8Shell L: Electron 2 of 8Shell L: Electron 3 of 8Shell L: Electron 4 of 8Shell L: Electron 5 of 8Shell L: Electron 6 of 8Shell L: Electron 7 of 8Shell L: Electron 8 of 8MShell M: Electron 1 of 18Shell M: Electron 2 of 18Shell M: Electron 3 of 18Shell M: Electron 4 of 18Shell M: Electron 5 of 18Shell M: Electron 6 of 18Shell M: Electron 7 of 18Shell M: Electron 8 of 18Shell M: Electron 9 of 18Shell M: Electron 10 of 18Shell M: Electron 11 of 18Shell M: Electron 12 of 18Shell M: Electron 13 of 18Shell M: Electron 14 of 18Shell M: Electron 15 of 18Shell M: Electron 16 of 18Shell M: Electron 17 of 18Shell M: Electron 18 of 18NShell N: Electron 1 of 18Shell N: Electron 2 of 18Shell N: Electron 3 of 18Shell N: Electron 4 of 18Shell N: Electron 5 of 18Shell N: Electron 6 of 18Shell N: Electron 7 of 18Shell N: Electron 8 of 18Shell N: Electron 9 of 18Shell N: Electron 10 of 18Shell N: Electron 11 of 18Shell N: Electron 12 of 18Shell N: Electron 13 of 18Shell N: Electron 14 of 18Shell N: Electron 15 of 18Shell N: Electron 16 of 18Shell N: Electron 17 of 18Shell N: Electron 18 of 18OShell O: Electron 1 of 8Shell O: Electron 2 of 8Shell O: Electron 3 of 8Shell O: Electron 4 of 8Shell O: Electron 5 of 8Shell O: Electron 6 of 8Shell O: Electron 7 of 8Shell O: Electron 8 of 8XeZ = 54

Educational Note: This Niels Bohr planetary model visually illustrates principal quantum energy shells ($n=1, 2, 3\dots$) and electron counts. In modern quantum mechanics (Schrödinger model), electrons do not orbit in fixed circular planetary tracks, but exist as 3D probability clouds (orbitals: $s, p, d, f$) governed by the Heisenberg uncertainty principle.

Electron Shell Filling Breakdown

Shell K (n=1):2 / 2 electrons (100%)
Shell L (n=2):8 / 8 electrons (100%)
Shell M (n=3):18 / 18 electrons (100%)
Shell N (n=4):18 / 32 electrons (56%)
Shell O (n=5):8 / 50 electrons (16%)
Aufbau Electron Configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶

Neutral ground state configuration. Valence electrons: 8.

Atomic & Quantum Properties

Electronegativity (Pauling)2.6 Pauling
1st Ionization Energy1170.4 kJ/mol
Electron Affinity0 kJ/mol
Atomic Radius (empirical)108 pm
Common Oxidation States0, +2, +4, +6, +8
Crystal StructureFCC

Physical & Thermal Properties

Density at STP0.00589 g/cm³
Melting Point-111.7 °C (161.45 K)
Boiling Point-108.1 °C (165.05 K)
Magnetic OrderingDiamagnetic
Discovery Year1898
Discovered BySir William Ramsay & Morris Travers

Real-World Uses, Occurrence & Compounds

Major Industrial & Everyday Uses
  • Ion propulsion rocket thrusters for deep space probes (Dawn mission) and Starlink satellites
  • High-intensity xenon arc lamps for movie IMAX cinema projectors and automotive headlights
  • General anesthesia in high-risk cardiac surgeries with rapid neuroprotective recovery
  • Direct dark matter search detectors (liquid xenon cryogenic time-projection chambers / LUX-ZEPLIN)
Occurrence in Nature

Occurs as a trace component in Earth's atmosphere (0.087 parts per million by volume), extracted via cryogenic air fractionation.

Etymology & Name Origin

From Greek 'xenos' meaning stranger or foreign

Important Chemical Compounds
XeF₄ (Xenon tetrafluoride)
XeF₂ (Xenon difluoride)
XeF₆ (Xenon hexafluoride)
XeO₃ (Xenon trioxide)
Interesting Chemical Facts
  • In 1962, Neil Bartlett synthesized the very first noble gas compound in history (Xe[PtF₆]), overturning decades of scientific consensus that noble gases were completely inert.
  • Xenon ion engines accelerate positively charged xenon ions electrostatically to 30 km/s, providing months of fuel-efficient deep space propulsion.
  • Inhaling xenon produces an ultra-deep voice (the polar opposite of helium) because sound travels much slower through dense xenon gas.
Safety & Handling Note

Chemically non-toxic and non-reactive under normal conditions; acts as a potent anesthetic and simple asphyxiant.