Editing Radon (section)

=== Isotopes ===
{{Main|Isotopes of radon}}

Radon has no [[stable isotope]]s. Thirty-nine radioactive isotopes have been characterized, with [[mass number]]s ranging from 193 to 231.<ref name="Sonzogni-2011">{{cite web|author=Sonzogni, Alejandro|title=Interactive Chart of Nuclides|url=http://www.nndc.bnl.gov/chart/|access-date=2008-06-06|publisher=Brookhaven National Laboratory|location=National Nuclear Data Center|archive-date=2011-07-21|archive-url=https://web.archive.org/web/20110721051025/http://www.nndc.bnl.gov/chart/|url-status=dead}}</ref><ref name="229Rn">{{cite journal|last1=Neidherr|first1=D.|last2=Audi|first2=G.|last3=Beck|first3=D.|last4=Baum|first4=K.|last5=Böhm|first5=Ch.|last6=Breitenfeldt|first6=M.|last7=Cakirli|first7=R. B.|last8=Casten|first8=R. F.|last9=George|first9=S.|last10=Herfurth|first10=F.|last11=Herlert|first11=A.|date=19 March 2009|title=Discovery of {{sup|229}}Rn and the Structure of the Heaviest Rn and Ra Isotopes from Penning-Trap Mass Measurements|url=https://cds.cern.ch/record/1190495/files/PhysRevLett.102.112501.pdf|journal=[[Physical Review Letters]]|volume=102|issue=11|pages=112501–1–112501–5|bibcode=2009PhRvL.102k2501N|doi=10.1103/PhysRevLett.102.112501|pmid=19392194|last13=Kowalska|first21=L.|first12=A.|last12=Kellerbauer|last22=Stora|first22=T.|last21=Schweikhard|last20=Schwarz|first14=D.|first20=S.|last19=Rosenbusch|first19=M.|last18=Penescu|first18=L.|last17=Noah|first17=E.|last16=Naimi|first16=S.|last15=Minaya-Ramirez|first15=E.|first13=M.|last14=Lunney}}</ref> Six of them, from 217 to 222 inclusive, occur naturally. The most stable isotope is {{sup|222}}Rn (half-life 3.82&nbsp;days), which is a decay product of [[radium-226|{{sup|226}}Ra]], the latter being itself a decay product of [[uranium-238|{{sup|238}}U]].<ref>{{cite web|title=Principal Decay Scheme of the Uranium Series|url=http://www.gulflink.osd.mil/library/randrep/du/mr1018.7.appa.html|url-status=dead|archive-url=https://web.archive.org/web/20081025025424/http://www.gulflink.osd.mil/library/randrep/du/mr1018.7.appa.html|archive-date=2008-10-25|access-date=2008-09-12|publisher=Gulflink.osd.mil}}</ref> A trace amount of the (highly unstable) isotope {{sup|218}}Rn (half-life about 35&nbsp;[[millisecond]]s) is also among the daughters of {{sup|222}}Rn. The isotope {{sup|216}}Rn would be produced by the [[double beta decay]] of natural {{sup|216}}Po; while energetically possible, this process has however never been seen.<ref name="Tretyak2002">{{Cite journal
 |last1=Tretyak |first1=V.I. 
 |last2=Zdesenko |first2=Yu.G. 
 |year=2002
 |title=Tables of Double Beta Decay Data — An Update
 |journal=[[At. Data Nucl. Data Tables]] |volume=80 |issue=1 |pages=83–116
 |doi=10.1006/adnd.2001.0873
|bibcode=2002ADNDT..80...83T }}</ref>

Three other radon isotopes have a half-life of over an hour: {{sup|211}}Rn (about 15&nbsp;hours), {{sup|210}}Rn (2.4&nbsp;hours) and {{sup|224}}Rn (about 1.8&nbsp;hours). However, none of these three occur naturally. {{sup|220}}Rn, also called thoron, is a natural decay product of the most stable thorium isotope ({{sup|232}}Th). It has a half-life of 55.6 seconds and also emits [[alpha radiation]]. Similarly, {{sup|219}}Rn is derived from the most stable isotope of [[actinium]] ({{sup|227}}Ac)—named "actinon"—and is an alpha emitter with a half-life of 3.96 seconds.<ref name="Sonzogni-2011" /> <!-- No radon isotopes occur significantly in the neptunium (237Np) decay series, though trace amounts of the isotopes 221Rn (26 minutes) and 217Rn (0.5 millisecond) are produced in minor branches. -->
[[Image:Decay chain(4n+2, Uranium series).svg|thumb|upright=1.3|alt=Uranium series|The radium or uranium series]]