Half Life Of Radon 222
| General | |
|---|---|
| Symbol | 222Rn |
| Names | radon-222, Rn-222, Radium emanation |
| Protons (Z) | 86 |
| Neutrons (N) | 136 |
| Nuclide data | |
| Natural abundance | Trace |
| Half-life (t i/ii) | 3.8215 d [one] |
| Isotope mass | 222.0175763[2] Da |
| Spin | 0 |
| Parent isotopes | 226Ra (α) |
| Disuse products | 218Po |
| Disuse modes | |
| Decay mode | Decay energy (MeV) |
| Alpha decay | 5.5904[2] |
| Isotopes of radon Consummate table of nuclides | |
Radon-222 (222Rn, Rn-222, historically radium emanation or radon) is the most stable isotope of radon, with a half-life of approximately 3.viii days. It is transient in the decay chain of primordial uranium-238 and is the immediate decay production of radium-226. Radon-222 was showtime observed in 1899, and was identified as an isotope of a new chemical element several years subsequently. In 1957, the name radon, formerly the proper name of merely radon-222, became the name of the element. Owing to its gaseous nature and loftier radioactive decay, radon-222 is one of the leading causes of lung cancer.[iii]
History [edit]
Following the 1898 discovery of radium through chemical analysis of radioactive ore, Marie and Pierre Curie observed a new radioactive substance emanating from radium in 1899 that was strongly radioactive for several days.[4] Around the same time, Ernest Rutherford and Robert B. Owens observed a like (though shorter-lived) emission from thorium compounds.[5] German physicist Friedrich Ernst Dorn extensively studied these emanations in the early 1900s and attributed them to a new gaseous chemical element, radon. In detail, he studied the product in the uranium series, radon-222, which he called radium emanation.[6]
In the early on 20th century, the element radon was known by several different names. Chemist William Ramsay, who extensively studied the chemical element's chemical backdrop, suggested the proper noun niton, and Rutherford originally suggested emanation. At that time, radon but referred to the isotope 222Rn, whereas the names actinon and thoron denoted 219Rn and 220Rn, respectively.[7] In 1957, the International Union of Pure and Applied Chemistry (IUPAC) promoted the name radon to refer to the element rather than just 222Rn; this was done under a new rule concerning isotope naming conventions.[7] This decision was controversial because it was believed to requite undue credit to Dorn's identification of radon-222 over Rutherford's identification of radon-220, and the historical use of the name radon created confusion as to whether the chemical element or the isotope 222Rn was existence discussed.[7]
Disuse properties [edit]
The decay chain of uranium-238, known equally the uranium series or radium series, of which radon-222 is a member.
Radon-222 is generated in the uranium series from the alpha decay of radium-226, which has a half-life of 1600 years. Radon-222 itself alpha decays to polonium-218 with a half-life of approximately 3.82 days, making it the most stable isotope of radon.[1] Its terminal decay product is stable lead-206.
In theory, 222Rn is capable of double beta decay to 222Ra, and depending on the mass measurement, single beta decay to 222Fr may besides be allowed.[viii] [a] These decay modes have been searched for, yielding lower partial half-life limits of 8 years for both transitions. If the beta disuse of 222Rn is possible, it is predicted to have a very low decay energy (24 ± 21 keV) and thus a half-life on the order of 10v years, as well resulting in a very low branching probability relative to alpha decay.[eight]
Occurrence and hazards [edit]
All radon isotopes are hazardous owing to their radioactive decay, gaseous nature, chemical inertness, and radioactive decay of their decay products (progeny). Radon-222 is especially dangerous because its longer half-life allows it to permeate soil and rocks, where it is produced in trace quantities from decays of uranium-238, and concentrate in buildings and uranium mines. This contrasts with the other natural isotopes that disuse far more quickly (half-lives less than one infinitesimal) and thus do non contribute significantly to radiation exposure.[ix] At college concentrations, gaseous 222Rn may be inhaled and decay before exhalation, which leads to a buildup of its daughters 218Po and 214Po in the lungs, whose high-free energy alpha and gamma radiation damages cells. Extended periods of exposure to 222Rn and its progeny ultimately induce lung cancer.[9] Alternatively, radon may enter the body through contaminated drinking water or through the disuse of ingested radium[iii] – making radon diffusion one of the greatest dangers of radium.[10] Thus, 222Rn is a carcinogen; in fact, it is the second leading crusade of lung cancer in the United States after cigarette smoking,[3] with over 20,000 deaths per year attributed to radon-induced lung cancer.[nine] [11]
See also [edit]
- Isotopes of radon
Notes [edit]
- ^ AME2016 gives 222Rn a lower mass than 222Fr,[1] which would forestall single beta disuse, though it is possible inside the given error margin and is explicitly predicted by Belli et al.
References [edit]
- ^ a b c Audi, G.; Kondev, F. G.; Wang, One thousand.; Huang, W. J.; Naimi, S. (2017). "The NUBASE2016 evaluation of nuclear properties" (PDF). Chinese Physics C. 41 (3): 030001. Bibcode:2017ChPhC..41c0001A. doi:x.1088/1674-1137/41/3/030001.
- ^ a b Wang, M.; Audi, G.; Kondev, F. G.; Huang, W. J.; Naimi, Due south.; Xu, X. (2017). "The AME2016 atomic mass evaluation (II). Tables, graphs, and references" (PDF). Chinese Physics C. 41 (iii): 030003-i–030003-442. doi:x.1088/1674-1137/41/3/030003.
- ^ a b c EPA Facts near Radon (PDF) (Report). United States Environmental Protection Bureau. pp. 1–3. Retrieved 22 February 2019.
- ^ Fry, C.; Thoennessen, M. (2013). "Discovery of the astatine, radon, francium, and radium isotopes". Atomic Information and Nuclear Data Tables. 99 (5): 497–519. arXiv:1205.5841. Bibcode:2013ADNDT..99..497F. doi:10.1016/j.adt.2012.05.003. S2CID 12590893.
- ^ Thoennessen, 1000. (2016). The Discovery of Isotopes: A Complete Compilation. Springer. p. 8. doi:10.1007/978-three-319-31763-ii. ISBN978-iii-319-31761-8. LCCN 2016935977.
- ^ George, A.C. (2008). "World History of Radon Research and Measurement from the Early 1900s to Today" (PDF). AIP Briefing Proceedings. 1034 (1): twenty–36. Bibcode:2008AIPC.1034...20G. CiteSeerX10.1.1.618.9328. doi:10.1063/1.2991210.
- ^ a b c Thornton, B.F.; Burdette, S.C. (2013). "Recalling radon's recognition". Nature Chemical science. 5 (ix): 804. Bibcode:2013NatCh...5..804T. doi:10.1038/nchem.1731. PMID 23965684.
- ^ a b Belli, P.; Bernabei, R.; Cappella, C.; Caracciolo, 5.; Cerulli, R.; Danevich, F.A.; Di Marco, A.; Incicchitti, A.; Poda, D.V.; Polischuk, O.G.; Tretyak, 5.I. (2014). "Investigation of rare nuclear decays with BaF2 crystal scintillator contaminated by radium". European Physical Journal A. fifty (nine): 134–143. arXiv:1407.5844. Bibcode:2014EPJA...fifty..134B. doi:10.1140/epja/i2014-14134-six. S2CID 118513731.
- ^ a b c EPA assessment of risks from radon in homes (PDF) (Study). Office of Radiation and Indoor Air, The states Environmental Protection Agency. 2003.
- ^ "Radiation protection: Radium". United states of america Environmental Protection Agency. Archived from the original on 11 February 2015. Retrieved 22 February 2019.
- ^ "Radon Fact Canvass: What information technology is, how it affects us, why it matters". Air Chek, Inc. Retrieved 22 Feb 2019.
Half Life Of Radon 222,
Source: https://en.wikipedia.org/wiki/Radon-222
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