Xenon monofluoride

Xenon,  ₅₄Xe

A xenon-filled discharge tube glowing light blue
General properties
Pronunciation	/ˈzɛnɒn/ (ZEN-on) /ˈziːnɒn/ (ZEE-non)
Appearance	colorless gas, exhibiting a blue glow when placed in an electric field
Standard atomic weight (Ar, standard)	7002131293000000000♠131.293(6)
Xenon in the periodic table
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson Kr ↑ Xe ↓ Rn iodine ← xenon → caesium
Atomic number (Z)	54
Group	group 18 (noble gases)
Period	period 5
Element category	noble gas
Block	p-block
Electron configuration	[Kr] 4d10 5s2 5p6
Electrons per shell	2, 8, 18, 18, 8
Physical properties
Phase (at STP)	gas
Melting point	161.40 K ​(−111.75 °C, ​−169.15 °F)
Boiling point	165.051 K ​(−108.099 °C, ​−162.578 °F)
Density (at STP)	5.894 g/L
when liquid (at b.p.)	2.942 g/cm3
Triple point	161.405 K, ​81.77 kPa
Critical point	289.733 K, 5.842 MPa
Heat of fusion	2.27 kJ/mol
Heat of vaporization	12.64 kJ/mol
Molar heat capacity	21.01 J/(mol·K)
Vapor pressure P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 83 92 103 117 137 165
Atomic properties
Oxidation states	0, +1, +2, +4, +6, +8 ​(rarely more than 0; a weakly acidic oxide)
Electronegativity	Pauling scale: 2.6
Ionization energies	1st: 1170.4 kJ/mol 2nd: 2046.4 kJ/mol 3rd: 3099.4 kJ/mol
Covalent radius	140±9 pm
Van der Waals radius	216 pm
Spectral lines
Miscellanea
Crystal structure	​face-centered cubic (fcc)
Speed of sound	gas: 178 m·s−1 liquid: 1090 m/s
Thermal conductivity	5.65×10−3 W/(m·K)
Magnetic ordering	diamagnetic
Magnetic susceptibility	−43.9·10−6 cm3/mol (298 K)
CAS Number	7440-63-3
History
Discovery and first isolation	William Ramsay and Morris Travers (1898)
Main isotopes of xenon
Iso­tope Abun­dance Half-life (t1/2) Decay mode Pro­duct 124Xe 0.095% stable 125Xe syn 16.9 h ε 125I 126Xe 0.089% stable 127Xe syn 36.345 d ε 127I 128Xe 1.910% stable 129Xe 26.401% stable 130Xe 4.071% stable 131Xe 21.232% stable 132Xe 26.909% stable 133Xe syn 5.247 d β− 133Cs 134Xe 10.436% stable 135Xe syn 9.14 h β− 135Cs 136Xe 8.857% 2.165×1021 y β−β− 136Ba
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Xenon is a chemical element with symbol Xe and atomic number 54. It is a colorless, dense, odorless noble gas found 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.

Xenon is used in flash lamps and arc lamps, and as a general anesthetic. The first excimer laser design used a xenon dimer molecule (Xe₂) as the lasing medium, and the earliest laser designs used xenon flash lamps as pumps. Xenon is used to search for hypothetical weakly interacting massive particles and as the propellant for ion thrusters in spacecraft.

Naturally occurring xenon consists of eight stable isotopes. More than 40 unstable xenon isotopes undergo radioactive decay, and the isotope ratios of xenon are an important tool for studying the early history of the Solar System. Radioactive xenon-135 is produced by beta decay from iodine-135 (a product of nuclear fission), and is the most significant (and unwanted) neutron absorber in nuclear reactors.