Editing Tungsten (section)

===Isotopes===
{{Main|Isotopes of tungsten}}
Naturally occurring tungsten consists of four stable [[isotope]]s (<sup>182</sup>W, <sup>183</sup>W, <sup>184</sup>W, and <sup>186</sup>W) and one very long-lived radioisotope, <sup>180</sup>W. Theoretically, all five can decay into isotopes of element 72 ([[hafnium]]) by [[alpha emission]], but only <sup>180</sup>W has been observed to do so, with a half-life of {{val|1.8e18|0.2}} years;<ref>{{cite journal| author = Danevich, F. A. | display-authors = etal| title = α activity of natural tungsten isotopes| journal = Phys. Rev. C|volume = 67| issue = 1|page = 014310|date = 2003| arxiv = nucl-ex/0211013|doi = 10.1103/PhysRevC.67.014310|bibcode = 2003PhRvC..67a4310D | s2cid = 6733875}}</ref><ref>{{cite journal| author = Cozzini, C. | display-authors = etal| title = Detection of the natural α decay of tungsten| journal = Phys. Rev. C|volume = 70| issue = 6|page = 064606|date = 2004| arxiv = nucl-ex/0408006|doi = 10.1103/PhysRevC.70.064606|bibcode = 2004PhRvC..70f4606C | s2cid = 118891861}}</ref> on average, this yields about two alpha decays of <sup>180</sup>W per gram of natural tungsten per year.<ref name="isotopes">{{cite web|url=http://www.nndc.bnl.gov/chart/|title=Interactive Chart of Nuclides|publisher=Brookhaven National Laboratory|author=Sonzogni, Alejandro|location=National Nuclear Data Center|access-date=2008-06-06|url-status=live|archive-url=https://web.archive.org/web/20080522125027/http://www.nndc.bnl.gov/chart|archive-date=2008-05-22}}</ref> This rate is equivalent to a [[specific activity]] of roughly 63 micro-[[becquerel (unit)|becquerel]] per kilogram. This rate of decay is orders of magnitude lower than that observed in carbon or potassium as found on earth, which likewise contain small amounts of long-lived radioactive isotopes. [[Bismuth]] was long thought to be non-radioactive, but {{chem|209|Bi}} (its longest lived isotope) actually decays with a half life of {{val|2.01e19}} years or about a factor 10 slower than {{chem|180|W}}. However, due to naturally occurring bismuth being 100% {{chem|209|Bi}}, its specific activity is actually higher than that of natural tungsten at 3 milli-becquerel per kilogram. The other naturally occurring isotopes of tungsten have not been observed to decay, constraining their half-lives to be at least {{val|4|e=21|u=years}}.

Another 34 artificial [[radioisotope]]s of tungsten have been characterized, the most stable of which are <sup>181</sup>W with a half-life of 121.2&nbsp;days, <sup>185</sup>W with a half-life of 75.1&nbsp;days, <sup>188</sup>W with a half-life of 69.4&nbsp;days, <sup>178</sup>W with a half-life of 21.6&nbsp;days, and <sup>187</sup>W with a half-life of 23.72 h.<ref name="isotopes" /> All of the remaining [[radioactive]] isotopes have half-lives of less than 3&nbsp;hours, and most of these have half-lives below 8&nbsp;minutes.<ref name="isotopes" /> Tungsten also has 12&nbsp;[[meta state]]s, with the most stable being <sup>179m</sup>W (''t''<sub>1/2</sub>&nbsp;6.4&nbsp;minutes).