Eternal radiance of inert gases

Noble gases properties and applications


These el­e­ments be­long to the eighth group of the Pe­ri­od­ic Ta­ble, and pos­sess sta­ble, full elec­tron shells. In­ert gas­es, or no­ble gas­es, are monatom­ic gas­es with no col­or or smell. They glow bright­ly when cur­rent flows through them. They also liq­ue­fy and freeze at sig­nif­i­cant­ly low­er tem­per­a­tures than oth­er gas­es. He­li­um is the light­est among them, fol­lowed by neon, ar­gon, kryp­ton, xenon, and radon.

His­to­ry of dis­cov­ery

The first in­ert gas in the pe­ri­od­ic sys­tem and the first to be dis­cov­ered was he­li­um. It was ob­served for the first time by Jules Janssen in 1868 dur­ing a to­tal so­lar eclipse. A quar­ter of a cen­tu­ry lat­er, Lord Rayleigh and William Ram­say iso­lat­ed a new el­e­ment they called ar­gon. In 1898, William Ram­say and Mor­ris Travers dis­cov­ered kryp­ton, xenon, and neon. In 1904, Rayleigh and Ram­say re­ceived No­bel Prizes in Physics and Chem­istry, re­spec­tive­ly, for their dis­cov­er­ies and stud­ies on this top­ic.

Ex­trac­tion and chem­i­cal prop­er­ties

Neon, ar­gon, kryp­ton, and xenon are ex­tract­ed from the air. First, the air is pu­ri­fied of car­bon diox­ide and mois­ture and com­pressed via deep freeze. Next, the liq­uid air is grad­u­al­ly evap­o­rat­ed by a num­ber of frac­tion­al dis­til­la­tions. These four gas­es are sep­a­rat­ed dur­ing this process us­ing dif­fer­ent tech­ni­cal so­lu­tions. He­li­um is ob­tained via a sim­i­lar method, but from nat­u­ral gas. In­ert gas­es are prac­ti­cal­ly chem­i­cal­ly in­ac­tive due to pe­cu­liar­i­ties in their elec­tron shell struc­ture: their atoms have full va­lence elec­tron shells. Va­lence elec­trons are an atom’s out­er elec­trons, and are usu­al­ly the only elec­trons in­volved in chem­i­cal bond­ing. How­ev­er, heav­ier no­ble gas­es, due to the in­creased dis­tance of the va­lence elec­trons from the nu­cle­us, are ca­pa­ble of en­ter­ing into chem­i­cal bonds with strong ox­i­dants such as flu­o­rine and oxy­gen.


In­ert gas­es have a wide va­ri­ety of uses. He­li­um is in­cor­po­rat­ed in the com­po­si­tion of gas mix­tures used in scu­ba div­ing and to fill bal­loons. It can also tem­po­rar­ily af­fect the pitch of the voice if in­haled. Neon is main­ly used to fill apt­ly-named neon signs and, in liq­uid form, as a coolant. Ar­gon is used in plas­ma cut­ting and some sur­gi­cal pro­ce­dures. Kryp­ton is used to fuel SpaceX satel­lites’ elec­tric propul­sion sys­tems and man­u­fac­ture lasers. Xenon is main­ly uti­lized in IMAX film pro­jec­tion sys­tems and as a con­trast agent in CT and MRI scans.