Xenon is a chemical element with the symbol Xe and atomic number 54. It is a colorless, dense, odorless noble gas found in Earth's atmosphere in trace amounts.[11] Although generally unreactive, it can undergo a few chemical reactions such as the formation of xenon hexafluoroplatinate, the first noble gas compound to be synthesized.
After Neil Bartlett's discovery in 1962 that xenon can form chemical compounds, a large number of xenon compounds have been discovered and described. Almost all known xenon compounds contain the electronegative atoms fluorine or oxygen. The chemistry of xenon in each oxidation state is analogous to that of the neighboring element iodine in the immediately lower oxidation state.
Halides of Xenon:
Three fluorides are known: XeF
2, XeF
4, and XeF
6. XeF is theorized to be unstable.[96] These are the starting points for the synthesis of almost all xenon compounds.
The solid, crystalline difluoride XeF
2 is formed when a mixture of fluorine and xenon gases is exposed to ultraviolet light.[97] The ultraviolet component of ordinary daylight is sufficient.[98] Long-term heating of XeF
2 at high temperatures under an NiF
2 catalyst yields XeF
6.[99] Pyrolysis of XeF
6 in the presence of NaF yields high-purity XeF
4.[100]
The xenon fluorides behave as both fluoride acceptors and fluoride donors, forming salts that contain such cations as XeF+
 and Xe
2F+
3, and anions such as XeF−
5, XeF−
7, and XeF2−
8. The green, paramagnetic Xe+
2 is formed by the reduction of XeF
2 by xenon gas.[95]
XeF
2 also forms coordination complexes with transition metal ions. More than 30 such complexes have been synthesized and characterized.[99]
Whereas the xenon fluorides are well characterized, with the exception of dichloride XeCl2 and XeCl4, the other halides are not known. Xenon dichloride, formed by the high-frequency irradiation of a mixture of xenon, fluorine, and silicon or carbon tetrachloride,[101] is reported to be an endothermic, colorless, crystalline compound that decomposes into the elements at 80 °C. However, XeCl
2 may be merely a van der Waals molecule of weakly bound Xe atoms and Cl
2 molecules and not a real compound.[102] Theoretical calculations indicate that the linear molecule XeCl
2 is less stable than the van der Waals complex.[103] Xenon tetrachloride is more unstable that it cannot be synthesized by chemical reactions. It was created by radioactive 129
ICl−
4 decay.