Radon test kit, 1988
26 July 2024
Radon is a chemical element, a radioactive noble gas with atomic number 86 and the symbol Rn. It has few practical applications. Radon has long history of use in medical quackery, and is still occasionally used in legitimate nuclear medicine, although it has largely been replaced by other substances. Because radon is emitted from soil, measurements of radon concentrations is used in hydrologic and seismic research.
Radon gas, a decay product of thorium oxide, was discovered in 1899 by Ernest Rutherford and Robert Owens at McGill University in Montreal. A year later, the husband and wife team of Marie Sklodowska Curie and Pierre Curie observed it as a decay product of radium. As a result, the two decay products were initially dubbed thorium emanation, radium emanation, and, later when it was found to be emitted by actinium, actinium emanation.
These names proved cumbersome and didn’t conform to standard chemical nomenclature, so in 1904, William Ramsay and J. Norman Collie proposed three shortened names, exradio, exthorio, and exactino:
Now, it appears advisable to devise a name which should recall its source, and, at the same time, by its termination, express the radical difference which undoubtedly exists between it and other elements. As it is derived from radium, why not name it simply “exradio”? Should it be found that the emanation, which is supposed to be evolved from thorium, is really due to that element, and not to some other element mixed with thorium in exceedingly small amount, a similar name could be given, namely, “exthorio.” If the existence of actinium as a definite element is established, its emanation would appropriately be named “exactinio.” It is unlikely that others will be discovered, but, if they are, the same principle of nomenclature might be applied.
The names didn’t catch on, and in 1910 Ramsay tried again, this time with Robert Wytlaw-Gray and proposed the name niton because of its radioluminescent property, from the Latin nitere (to shine) + the -on suffix used for noble gases:
L'expression l’émanation du radium est fort incommode; il est certain que c'est un élément aussi bien caractérisé,que les autres, avec son spectre, décrit d'abord par Cottie et Ramsay, et étudié par Watson, sous la direction de Ramsay; nous avons maintenant déterminé par des moyens bien connus son poids atomique avec une exactitude approximative;nous l'avons liquéfié et nous avons mesuré des pressions de vapeur; cet élément appartient à la série des gaz inactifs de l'atmosphère, étant même un constituant normal de l'air atmosphérique; et pour le ranger dans sa classe, nous faisons la proposition de le nommer Niton, brillant, pour rappeler ses propriétés phosphorescentes, dont l'abréviation peut s'écrire Ni.
(The expression emanation of radium is very inconvenient; it is certain that it is an element as well characterized as the others, with its spectrum, first described by Cottie and Ramsay, and studied by Watson, under the direction of Ramsay; we have now determined by well-known means its atomic weight with approximate accuracy; we have liquefied it and measured vapor pressures; this element belongs to the series of inactive gases of the atmosphere, even being a normal constituent of atmospheric air; and to place it in its class, we propose to name it Niton, brilliant, to recall its phosphorescent properties, the abbreviation of which can be written Ni.)
Again, these names didn’t gain widespread acceptance, and the name radon was proposed by Curt Schmidt in 1917:
Daß der von im für die Radiumemanation in Vorschlag gebrachte Name Niton keine allgemeine Annahme gefunden hat, erklärt sich, we SODDY wohl mit Recht bemerkt, hauptsächlich daraus, daß “der ersprüngliche Name offenbare Vorteile dadurch bietet, daß er die radioaktive Verwandtschaft zum Ausdruck bringt, und weil es von Nachteil ist, nur für eine der drei bekannten Emanationen einen neuen Namen vorschlagen.” Demgemäß gestatte ich mir, für die drei Emanationen die aus der ersten und letzten Silbe der bisherigen schwerfälligen Bezeichnungsweise zusammengezogenen Namen
Radon Ro
Thoron To
Akton Aoin Vorschlag zu bringen, eine Benennung, die nicht nur den in SODDYS Worten liegenden Forderungen gerecht wird, sondern sich außer präziser Kürze noch dadurch auszeichnet, daß die Wortbildung konform mit der für die anderen Glieder der Edelgasgruppe ist.
(The fact that the name Niton proposed by him for the radium emanation has not found general acceptance is explained, as SODDY rightly points out, mainly by the fact that "the original name offers obvious advantages in that it expresses the radioactive relationship, and because it is disadvantageous to propose a new name for only one of the three known emanations." Accordingly, I take the liberty of suggesting the names for the three emanations:
Radon Ro
Thoron To
Akton Aoin which are drawn from the first and last syllables of the previous cumbersome naming convention, a name which not only meets the requirements of SODDY’s words but is also distinguished by the fact that the word formation is consistent with that for the other members of the noble gas group, in addition to being precise and brief.)
But soon it was discovered that these three were just different isotopes of the same element, and in 1923 the International Union of Pure and Applied Chemistry chose radon as the official name because it was the most stable isotope of the three, 222Rn, the decay product of radium. It also adopted the symbol Rn, instead of Schmidt’s Ro. Thoron and akton became 220Rn and 219Rn, respectively.
Sources:
Miśkowiec, Pawel. “Name Game: The Naming History of the Chemical Elements: Part 2—Turbulent Nineteenth Century.” Foundations of Chemistry, 8 December 2022. DOI: 10.1007/s10698-022-09451-w.
Oxford English Dictionary, third edition, June 2008, radon, n., December 2003, niton, n.; second edition, 1989, emanation, n.
Ramsay, William and J. Norman Collie. “The Spectrum of Radium Emanation” (18 May 1904). Proceedings of the Royal Society of London, 73.488, July 1904, 470–76 at 476. DOI: 10.1098/rspl.1904.0064.
Ramsay, William and Robert Whytlaw Gray. “La densité de l'émanation du radium.” Comptes rendus hebdomadaires des séances de l'Académie des sciences, 151.2, 11 July 1910, 126–128. BnF Gallica.
Schmidt, Curt. “Periodisches System und Genesis der Elemente” (22 November 1917). Zeitschrift für anorganische und allgemeine Chemie, 103.1, 14 May 1918, 79–118 at 113–14. DOI: 10.1002/zaac.19181030106
Photo Credit: Unknown photographer, National Cancer Institute, National Institutes of Health, 1988. Wikimedia Commons. Public domain image.