What is Noble gas compound?
A '''noble gas compound''' is a [[chemical compound]] that has an [[Chemical element|element]] from [[Periodic table group|Group]] 18 of the [[periodic table]] in it. Group 18 (previously called Group 0) contains all the [[noble gas]]es. == History == For a long time, [[scientist]]s thought that noble gases could not form compounds because their [[Valence electron|valence]] [[electron shell]] had no space for more [[electron]]s. This means that they could not accept any more electrons, which made [[bonding]] impossible. However, in 1933, [[Linus Pauling]] said that heavy noble gases could react with [[fluorine]] or [[oxygen]], as they are the most [[electronegative]] atoms. His prediction was correct, and [[xenon hexafluoride]] ([[Xenon|Xe]][[Fluorine|F]]<sub>6</sub>) was later discovered. Many more noble gas compounds have been found since then. Oxidizing [[Helium]] or [[Neon]] takes a lot of energy. No chemical substance is known to have enough power to oxidize Helium or Neon. Two Helium compounds have been predicted; they would need a very high pressure to be stable. == Fullerene properties == [[File:Endohedral fullerene.png|thumb|right|An endohedral fullerene]] Noble gases can also make [[endohedral fullerene]] compounds when the noble gas atom is pushed inside a [[fullerene]] molecule. In 1993, it was discovered that when C<sub>60</sub> is put under pressure of about 3 [[bar (unit)|bar]] of Helium or Neon, He@C<sub>60</sub> and Ne@C<sub>60</sub> are made.<ref>{{cite journal|title=Stable compounds of helium and neon. He@C60 and Ne@C60|author=M. Saunders, H. A. Jiménez-Vázquez, R. J. Cross, and R. J. Poreda|journal=[[Science (journal)|Science]]|year=1993|volume=259|issue=5100|pages=1428–1430|doi=10.1126/science.259.5100.1428|pmid=17801275|bibcode=1993Sci...259.1428S|s2cid=41794612}}</ref> Only about one out of every 650,000 C<sub>60</sub> were found with a [[helium]] atom. But with more pressures (about 3000 bar), it is possible to get as much as 0.1%. Endohedral molecules with [[argon]], [[krypton]] and