Elementymology & Elements Multidict by Peter van der Krogt
Radon
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Multilingual dictionary
Language key
Indo-European
Germanic
Radon en de lb nl af fy da sv no is fo
Italic
Radon fr oc gl it fur ro arm
Radón es
Radó ca
Rádon pt
Slavic
Ðàäîí [radon] ru uk by sr mk bg
Radon pl cs sl hr bos
Radón sk
Redón kas
Baltic
Radonas lt
Radons lv
Radonan sud
Celtic
Radon cy gd cor br
Radón ga
Raadon gv
Other Indo-European
Ραδονιο [radonio] el
Radon sq
Ռադոն [ŗadon] hy
Indo-Iranian
Ðàäîí [radon] oss
Uralic
Radon fi hu
Radoon et
Радон [radon] mok
Altaic
Radon tr tg
Ðàäîí [radon] kk uz mn
Other (Europe)
Radona eu
რადონი [radoni] ka
East- & South-Asia
ラドン [radon] ja
[dong1 / dung1] zh (mand./cant.)
라돈 [radon] ko
Rađơn vi
เรดอน [rēdon] th
Radon ms
ரேடோன் [rēţōn] ta
Afro-Asiatic
رادون [rādūn] ar
Radon mt
רדון [radon] he
Africa
Radoni sw
Artificial
Radono eo New names
Radon (RDO) aen
Kilonoble dms
Appearance, some properties, a memory peg and a summary of discovery and etymology
Heavy radioactive gas
m.p. -71 ºC; -96 ºF
b.p. -61.8 ºC; -79.2 ºF
density (gas) 0.00973, (liquid at -62 ºC) 4.4 g/cc; (gas) 0.60742, (liquid at -79.6 ºC) 274.7 pound/cubic foot
memory peg

1899 Pierre & Marie Curie, France
radium = element #88

History & Etymology

Ernest Rutherford In 1899, Robert B. Owens (1870-), professor of electrical engineering at McGill University in Montreal, was trying to measure radiation from Thorium. Every time he made a measurement, he got a different result. Together with Ernest Rutherford (1871-1937), also teaching at McGill University, he studied this phenomenon and they observed that

"the radiation from thorium oxide was not constant, but varied in a most capricious manner." whereas "all the compounds of Uranium give out a radiation which is remarkably constant" (note).
Rutherford concluded that Thorium compounds continuously emit a radioactive gas which retain their radioactive powers for several minutes. He called this gas "emanation", from Latin "emanare" - to elapse and "emanatio" - expiration (note), hence Thorium Emanation (Th Em).

In the same year Pierre and Marie Curie observed a similar phenomenon with Radium, except that the "gas" emitted by Radium remained radioactive for a month (note). In 1900, Friedrich Ernst Dorn (1848-1916) confirmed the findings of Rutherford and the Curies (note), thus Radium Emanation (Ra Em). Most standard sources on the chemical elements list Dorn as the discoverer in 1900. In fact he had merely repeated the Curies’ experiment with more active Radium compounds.

In fact that the emanations emitted by Radium are a radioactive gas was clearly demonstrated by Rutherford and Brooks in 1901, though they were careful to give credit to the prior observations of the Curies (note).

In 1903, Fritz Giesel observed emanations from Emanium (note) and in the same year André-Louis Debierne (1874-1949) from Actinium (note). In 1906, when was concluded that Giesel's Emanium was identical with Debierne's Actinium, both emanations were therefore called Actinium Emanation (Ac Em).

The likeness of the spectra of these three gases with those of Argon, Krypton and Xenon, and its chemical inertia suggested that the "emanations" could contain a new element from the noble gases family. Several names were suggested:

  Radium Emanation Thorium Emanation Actinium Emanation
Ramsay & Collie, 1904 Exradio Exthorio Exactinio
Perrin, 1919 Radeon Thoreon Actineon
Schmidt, 1918 Radon Thoron Akton
Adams, 1920 Radon Thoron Actinon

Sir William Ramsay and J. Norman Collie wrote about their suggestion in 1904:
"It may be remembered that, at the Chemical Congress held in Paris in 1900, it was suggested that no element should receive a name until its spectrum had been mapped. (...) The «emanation from radium», however, is a cumbrous expression, and sufficient evidence has now been accumulated that it is an element, accepting that word in the usual sense. It is true that it is only a transient element, and ought in justice to be called a compound; but of what? It stands on a wholly different plane to any known compound (...) It is a gas; it follows Boyle's law; (...) it resembles the gases of the argon series in its indifference to chemical reagents (...) 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 appropiately be named «exactinio»." (note)
In 1910 Sir William Ramsay, whose 1904 suggestion was not followed, together with Robert W. Whytlaw-Gray again tried to change the cumbersome name. "L'expression l'émanation du radium est fort incommode," they wrote and suggested the new name Niton (symbol Ni), from Latin "nitens" (shining) (note). With this name he obviously desired to emphasize the property of gas to cause the phosphorescence of some substances. In 1912 this name was accepted by the International Commission for Atomic Weights. However, until 1923 the three gases were usually named Radium Emanation, Thorium Emanation, and Actinium Emanation.
(John and Gordon Marks suggested in 1994 Ramsay's name Niton (Nt) for the element. 'Radon' is short for 'radium emanation', Nt-222, and is thus merely an isotope of niton. Similarly thoron is Nt-220 and actinon is Nt-219. We do not refer to hydrogen as 'protium') (note).)

In 1923, the International Committee for Chemical Elements and the Union internationale de la chimie pure et appliquée chose for the names proposed by Schmidt and Adams: Radon, Thoron, and Actinon, with symbols Rn, Tn, and An.

Later, when isotopes were numbered instead of named, the name of the element became Radon.

Historical names of Radon isotopes
Name & Symbol (hist. and modern) First described Notes
Radium Emanation
1912: Niton, 1923: Radon
Ra Em
Ni, Rn
222Rn 1899/
1900
Pierre & Marie Curie
Friedrich E. Dorn
 
Thorium Emanation
1923: Thoron
Th Em
Tn
220Rn 1900 Ernest Rutherford  
Actinium Emanation
1923: Actinon
Ac Em
An
219Rn 1903 A. Debierne and Friedrich O. Giesel  

Further reading:

  • McGill Rutherford Museum, Emanations from Thorium and Radium (on line).
  • Edelgase. Gmelins Handbuch der anorganische Chemie, 8. Aufl.; System-Nummer 1 (1926).
  • David J. Brenner, Rutherford, the Curies, and Radon (PDF on line)
  • Was ist Radon? (on line).

Sources

Last update:
© Peter van der Krogt