History (and pre-history) of the discovery and chemistry of the noble gases

Abstract

Cavendish's 1783 measurements showing that around 1/120 of the vol. of air appeared to be neither nitrogen or oxygen, along with Lockyer's 1868 observation of a solar spectral line that corresponded to no known element on earth, were early but unrecognized hints of elements that could not be accommodated in Mendeleev's Periodic Table. Following a series of painstaking expts., in 1895 Lord Rayleigh and William Ramsay announced the isolation of a new element, which they called argon. Their claim was widely challenged - not least by Mendeleev himself - with alternate interpretations, particularly that the substance was actually N_3, an allotrope of nitrogen analogous to ozone. Within the next few years, though, Ramsay demonstrated the existence of four more such inert gases: He, isolated from minerals and shown to exhibit the mystery solar spectral line; and Ne, Kr, and Xe, by cryogenic fractionation of air. Ramsay inserted a place in the Periodic Table for this new group in 1896; Frederick Soddy added Rn in 1903; and Ramsay received the chem. Nobel Prize in 1904. Attempts to induce reactivity began almost immediately, but with no (reproducible) success. Friedrich Paneth proclaimed in 1924 that the unreactivity of the noble gases "belongs to the surest of exptl. results," while others - notably Linus Pauling - insisted that they should form compds. under the right conditions. In 1933, at Pauling's instigation, Caltech chemist Don Yost carried out an unsuccessful assault on xenon's inertness, which was finally overcome three decades later. Neil Bartlett's discovery of "Xe+[PtF_6]-" was followed quickly by extensive demonstrations of chem. reactivity, along with considerable speculation on the reasons for Yost's failure. I will very briefly summarize the former, and offer my own interpretation of the latter.