Editing Decay chain (section)

=== Thorium series ===
[[Image:Decay Chain Thorium.svg|thumb|300px|right]]
The 4n chain of thorium-232 is commonly called the "thorium series" or "thorium cascade". Beginning with naturally occurring thorium-232, this series includes the following elements:  [[actinium]], [[bismuth]], lead, [[polonium]], radium, radon and [[thallium]].  All are present, at least transiently, in any natural thorium-containing sample, whether metal, compound, or mineral. The series terminates with lead-208.

Plutonium-244 (which appears several steps above thorium-232 in this chain if one extends it to the transuranics) was present in the early Solar System,<ref name=Davis/> and is just long-lived enough that it should still survive in trace quantities today,<ref name="PU244">{{cite journal | last1 = Hoffman | first1 = D. C. | last2 = Lawrence | first2 = F. O. | last3 = Mewherter | first3 = J. L. | last4 = Rourke | first4 = F. M. | year = 1971| title = Detection of Plutonium-244 in Nature | journal = [[Nature (journal)|Nature]] | volume =  234| issue = 5325 | pages =  132–134| doi = 10.1038/234132a0 | bibcode = 1971Natur.234..132H | s2cid = 4283169 }}</ref> though it is uncertain if it has been detected.<ref name="PRC">{{cite journal|last=Lachner|first=J.|display-authors=etal|date=2012|title=Attempt to detect primordial <sup>244</sup>Pu on Earth|journal=Physical Review C|volume=85|issue=1 |pages=015801| doi=10.1103/PhysRevC.85.015801|bibcode=2012PhRvC..85a5801L}}</ref>

The total energy released from thorium-232 to lead-208, including the energy lost to neutrinos, is 42.6&nbsp;MeV.

{| class="wikitable" style="margin:auto; text-align:center;"
!rowspan=2|Nuclide
!colspan=2|Historic names
!rowspan=2|Decay mode
!rowspan=2|Half-life<br />(''a'' = years)
!rowspan=2|Energy released<br/>MeV
!rowspan=2|Decay<br/>product
|-
!Short!!Long
|-
| [[Californium-252|<sup>252</sup>Cf]]
| 
| 
| [[alpha decay|α]]
| 2.645 a
| 6.1181
| [[Curium-248|<sup>248</sup>Cm]]
|-
| <sup>248</sup>Cm
| 
| 
| α
| 3.4{{e|5}} a
| 5.162
| [[Plutonium-244|<sup>244</sup>Pu]]
|-
|<sup>244</sup>Pu
|
|
|α
|8{{e|7}} a
|4.589
|[[Uranium-240|<sup>240</sup>U]]
|-
| <sup>240</sup>U
| 
| 
| [[beta decay|β<sup>−</sup>]]
| 14.1 h
| 0.39
| [[Neptunium-240|<sup>240</sup>Np]]
|-
| <sup>240</sup>Np
| 
| 
| β<sup>−</sup>
| 1.032 h
| 2.2
| [[Plutonium-240|<sup>240</sup>Pu]]
|-
| <sup>240</sup>Pu
| 
| 
| α
| 6561 a
| 5.1683
| [[Uranium-236|<sup>236</sup>U]]
|-
| <sup>236</sup>U
| 
| Thoruranium<ref name=thoruranium>{{cite journal |last1=Trenn |first1=Thaddeus J. |date=1978 |title=Thoruranium (U-236) as the extinct natural parent of thorium: The premature falsification of an essentially correct theory |journal=Annals of Science |volume=35 |issue=6 |pages=581–97 |doi=10.1080/00033797800200441}}</ref>
| α
| 2.3{{e|7}} a
| 4.494
| [[Thorium-232|<sup>232</sup>Th]]
|-
| <sup>232</sup>Th
| Th
| Thorium
| α
| 1.405{{e|10}} a
| 4.081
| [[Radium-228|<sup>228</sup>Ra]]
|-
| <sup>228</sup>Ra
| MsTh<sub>1</sub>
| Mesothorium 1
| β<sup>−</sup>
| 5.75 a
| 0.046
| [[Actinium-228|<sup>228</sup>Ac]]
|-
| <sup>228</sup>Ac
| MsTh<sub>2</sub>
| Mesothorium 2
| β<sup>−</sup>
| 6.25 h
| 2.124
| [[Thorium-228|<sup>228</sup>Th]]
|-
| <sup>228</sup>Th
| RdTh
| Radiothorium
| α
| 1.9116 a
| 5.520
| [[Radium-224|<sup>224</sup>Ra]]
|-
| <sup>224</sup>Ra
| ThX
| Thorium X
| α
| 3.6319 d
| 5.789
| [[Radon-220|<sup>220</sup>Rn]]
|-
| <sup>220</sup>Rn
| Tn
| Thoron,<br />Thorium Emanation
| α
| 55.6 s
| 6.404
| [[Polonium-216|<sup>216</sup>Po]]
|-
| <sup>216</sup>Po
| ThA
| Thorium A
| α
| 0.145 s
| 6.906
| [[Lead-212|<sup>212</sup>Pb]]
|-
| <sup>212</sup>Pb
| ThB
| Thorium B
| β<sup>−</sup>
| 10.64 h
| 0.570
| [[Bismuth-212|<sup>212</sup>Bi]]
|-
| <sup>212</sup>Bi
| ThC
| Thorium C
| β<sup>−</sup> 64.06% <br /> α 35.94%
| 60.55 min
| 2.252 <br /> 6.208
| [[Polonium-212|<sup>212</sup>Po]] <br /> [[Thallium-208|<sup>208</sup>Tl]]
|-
| <sup>212</sup>Po
| ThC′
| Thorium C′
| α
| 294.4 ns<ref>{{NUBASE2020}}</ref>
| 8.954<ref>{{cite web |author=[[National Nuclear Data Center]] |title=NuDat 3.0 database |url=https://www.nndc.bnl.gov/nudat3/ |publisher=[[Brookhaven National Laboratory]]|access-date=19 Feb 2022}}</ref>
| [[Lead-208|<sup>208</sup>Pb]]
|-
| <sup>208</sup>Tl
| ThC″
| Thorium C″
| β<sup>−</sup>
| 3.053 min
| 5.001<ref>{{Cite web|url=https://pripyat.mit.edu/KAERI/cgi-bin/nuclide?nuc=Tl-208|access-date=2025-04-04}}</ref>
| <sup>208</sup>Pb   
|-
| <sup>208</sup>Pb
| ThD
| Thorium D
| stable
| —
| —
| —
|}