Noble Gases
. Noble Gases, also inert gases, group of six gaseous chemical elements constituting the group 18 (or VIIIa) of the periodic table . They are, in order of increasing atomic weight, helium , neon , argon , krypton , xenon , and radon . For many years chemists believed that these gases, because their outermost shells were completely filled with electrons, were inert—that is, that they would not enter into chemical combinations with other elements or compounds. This is now known not to be true, at least for the four heaviest inert gases—argon, krypton, xenon, and radon. In 1962, Neil Bartlett, a British chemist working in Canada, succeeded in making the first complex xenon compound. His work was confirmed by scientists at Argonne National Laboratory in Illinois, who made the first simple compound of xenon and fluorine (xenon tetrafluoride) and later made radon and krypton compounds. Although krypton compounds were made with considerable difficulty, both xenon and radon reacted readily wit