Editing Decay chain (section)

== Heavy nuclei (actinide) decay chains ==
{{Actinidesvsfissionproducts}}
In the four tables below, the minor branches of decay (with the branching probability of less than 0.0001%) are omitted. The energy release includes the total kinetic energy of all the emitted particles ([[electron]]s, [[alpha particle]]s, [[Gamma rays|gamma quanta]], [[neutrino]]s, [[Auger electron]]s and [[X-ray]]s) and the recoil nucleus, assuming that the original nucleus was at rest. The letter 'a' represents a year (from the Latin ''[[:wikt:annus|annus]]'').

In the tables below (except neptunium), the historic names of the naturally occurring nuclides are also given. Such names were used at the time when the decay chains were first discovered and investigated; the system listed was only finalized in the 1920s but it would be too confusing to give earlier names also. From these historical names one can thus find the modern isotopic designation.

The three naturally-occurring actinide alpha decay chains given below—thorium, uranium/radium (from uranium-238), and actinium (from uranium-235)—each ends with its own specific lead isotope (lead-208, lead-206, and lead-207 respectively). All these isotopes are stable and are also present in nature as [[primordial nuclide]]s, so their excess amounts in comparison with lead-204 (which has only a primordial origin) are required for accurate [[uranium–lead dating]] of rocks. Correlating more than one results in [[lead-lead dating]], capable of every greater accuracy.
{{Clear}}

=== 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
| —
| —
| —
|}

===Neptunium series===
[[Image:Decay Chain(4n+1, Neptunium Series).svg|300px|thumb|right]]
The 4n + 1 chain of neptunium-237 is commonly called the "neptunium series" or "neptunium cascade". In this series, only two of the isotopes involved are found naturally in significant quantities, namely the final two: bismuth-209 and thallium-205. Some of the other isotopes have been detected in nature, originating from trace quantities of <sup>237</sup>Np produced by the (n,2n) [[spallation|knockout]] reaction in primordial <sup>238</sup>U.<ref name=4n1>{{cite journal |last1=Peppard |first1=D. F. |last2=Mason |first2=G. W. |last3=Gray |first3=P. R. |last4=Mech |first4=J. F. |title=Occurrence of the (4n + 1) series in nature |journal=Journal of the American Chemical Society |date=1952 |volume=74 |issue=23 |pages=6081–6084 |doi=10.1021/ja01143a074 |bibcode=1952JAChS..74.6081P |url=https://digital.library.unt.edu/ark:/67531/metadc172698/m2/1/high_res_d/metadc172698.pdf }}</ref> A [[smoke detector]] containing an [[americium-241]] ionization chamber accumulates a significant amount of [[neptunium]]-237 as its americium decays. The following elements are also present in it, at least transiently, as decay products of the neptunium:  actinium, [[astatine]], bismuth, [[francium]], lead, polonium, [[protactinium]], radium, radon, thallium, thorium, and [[uranium]]. Since this series was only discovered and studied in 1947–1948,<ref name=th2>{{Thoennessen2016|pages=20}}</ref> its nuclides were never given historic names. One unique trait of this decay chain is that the noble gas radon is only produced in a rare branch (not shown in the illustration) but not the main decay sequence; thus, radon from this decay chain does not migrate through rock nearly as much as from the other three. Another unique trait of this decay sequence is that it ends in thallium (practically speaking, bismuth) rather than lead. This series terminates with the stable isotope thallium-205.

The total energy released from californium-249 to thallium-205, including the energy lost to [[neutrino]]s, is 66.8&nbsp;MeV.

{| class="wikitable" style="margin:auto; text-align:center;"
!Nuclide
!Decay mode
!Half-life<br />(''a'' = years)
!Energy released<br/>MeV
!Decay product
|-
|[[Californium-249|<sup>249</sup>Cf]]
|[[alpha decay|α]]
|351 a
|5.813+.388
|[[Curium-245|<sup>245</sup>Cm]]
|-
| <sup>245</sup>Cm
| α
| 8500 a
| 5.362+.175
| [[Plutonium-241|<sup>241</sup>Pu]]
|-
| <sup>241</sup>Pu
| [[beta decay|β<sup>−</sup>]]
| 14.4 a
| 0.021
| [[Americium-241|<sup>241</sup>Am]]
|-
| <sup>241</sup>Am
| α
| 432.7 a
| 5.638
| [[Neptunium-237|<sup>237</sup>Np]]
|-
| <sup>237</sup>Np
| α
| 2.14×10<sup>6</sup> a
| 4.959
| [[Protactinium-233|<sup>233</sup>Pa]]
|-
| <sup>233</sup>Pa
| β<sup>−</sup>
| 27.0 d
| 0.571
| [[Uranium-233|<sup>233</sup>U]]
|-
| <sup>233</sup>U
| α
| 1.592×10<sup>5</sup> a
| 4.909
| [[Thorium-229|<sup>229</sup>Th]]
|-
| <sup>229</sup>Th
| α
| 7340 a
| 5.168
| [[Radium-225|<sup>225</sup>Ra]]
|-
| <sup>225</sup>Ra
| β<sup>−</sup> 99.9974%<br />α 0.0026%
| 14.9 d
| 0.36<br />5.097
| [[Actinium-225|<sup>225</sup>Ac]]<br />[[Radon-221|<sup>221</sup>Rn]]
|-
| <sup>225</sup>Ac
| α
| 10.0 d
| 5.935
| [[Francium-221|<sup>221</sup>Fr]]
|-
| <sup>221</sup>Rn
| β<sup>−</sup> 78%<br />α 22%
| 25.7 min
| 1.194<br />6.163
| [[Francium-221|<sup>221</sup>Fr]]<br />[[Polonium-217|<sup>217</sup>Po]]
|-
| <sup>221</sup>Fr
| α 99.9952% <br /> β<sup>−</sup> 0.0048%
| 4.8 min
| 6.458<br /> 0.314
| [[Astatine-217|<sup>217</sup>At]]<br />[[Radium-221|<sup>221</sup>Ra]]
|-
| <sup>221</sup>Ra
| α
| 28 s
| 6.880
| [[Radon-217|<sup>217</sup>Rn]]
|-
| <sup>217</sup>Po
| α 97.5% <br /> β<sup>−</sup> 2.5%
|1.53 s
| 6.662<br />1.488
|[[Lead-213|<sup>213</sup>Pb]] <br /> [[Astatine-217|<sup>217</sup>At]]
|-
| <sup>217</sup>At
| α 99.992% <br /> β<sup>−</sup> 0.008%
|32 ms
| 7.201 <br /> 0.737
|[[Bismuth-213|<sup>213</sup>Bi]] <br /> [[Radon-217|<sup>217</sup>Rn]]
|-
| <sup>217</sup>Rn
|  α
| 540 μs
| 7.887
| [[Polonium-213|<sup>213</sup>Po]]
|-
| <sup>213</sup>Pb
|  β<sup>−</sup>
| 10.2 min
|2.028
| [[Bismuth-213|<sup>213</sup>Bi]]
|-
| <sup>213</sup>Bi
|  β<sup>−</sup> 97.80% <br />  α 2.20%
| 46.5 min
| 1.423 <br /> 5.87
| [[Polonium-213|<sup>213</sup>Po]] <br /> [[Thallium-209|<sup>209</sup>Tl]]
|-
| <sup>213</sup>Po
|  α
| 3.72 μs
| 8.536
| [[Lead|<sup>209</sup>Pb]]
|-
| <sup>209</sup>Tl
|  β<sup>−</sup>
| 2.2 min
| 3.99
| [[Lead-209|<sup>209</sup>Pb]]
|-
| <sup>209</sup>Pb
|  β<sup>−</sup>
| 3.25 h
| 0.644
| [[Bismuth-209|<sup>209</sup>Bi]]
|-
| <sup>209</sup>Bi
| α
| 2.01×10<sup>19</sup> a
| 3.137
| [[Thallium-205|<sup>205</sup>Tl]]
|-
| <sup>205</sup>Tl
| .
| stable
| .
| .
|}

=== {{anchor|Radium series}} Uranium series ===
[[Image:Decay chain(4n+2, Uranium series).svg|thumb|right|350px|alt=Uranium series|[[commons:File:Uranium series.gif|(More comprehensive graphic)]]]]
The 4n+2 chain of uranium-238 is called the "uranium series" or "radium series". Beginning with naturally occurring uranium-238, this series includes the following elements:  astatine, bismuth, [[lead]], [[mercury (element)|mercury]], polonium, [[protactinium]], [[radium]], [[radon]], thallium, and thorium.  All are present, at least transiently, in any natural uranium-containing sample, whether metal, compound, or mineral. The series terminates with lead-206.

The total energy released from uranium-238 to lead-206, including the energy lost to neutrinos, is 51.7&nbsp;MeV.

<!--{{Radium series/table}}-->
{| class="wikitable" style="margin:auto; text-align:center;"
!rowspan=2|Parent<br/>nuclide
!colspan=2|Historic name<ref name=th1>{{Thoennessen2016|pages=19}}</ref>
!rowspan=2|Decay mode <ref name="NdsEnsdf" group="RS">{{cite web|url=https://www-nds.iaea.org/relnsd/NdsEnsdf/QueryForm.html|title=Evaluated Nuclear Structure Data File|publisher=National Nuclear Data Center}}</ref>
!rowspan=2|Half-life<br />(''a''= years)
!rowspan=2 data-sort-type="number"|Energy released<br/>MeV<ref name="NdsEnsdf" group="RS"/>
!rowspan=2 data-sort-type="number"|Decay<br/>product<ref name="NdsEnsdf" group="RS"/>
|-
!Short!!Long
|-
| align="center"| [[Californium-250|<sup>250</sup>Cf]]
| align="center"| 
| align="center"| 
| align="center"| [[alpha decay|α]]
| align="center"| 13.08 a
| align="center"| 6.12844
| align="center"| [[Curium-246|<sup>246</sup>Cm]]
|-
| align="center"| [[Curium-246|<sup>246</sup>Cm]]
| align="center"| 
| align="center"| 
| align="center"| [[alpha decay|α]]
| align="center"| 4800 a
| align="center"| 5.47513
| align="center"| [[Plutonium-242|<sup>242</sup>Pu]]
|-
| align="center"| [[Plutonium-242|<sup>242</sup>Pu]]
| align="center"| 
| align="center"| 
| align="center"| [[alpha decay|α]]
| align="center"| 3.8×10<sup>5</sup> a
| align="center"| 4.98453
| align="center"| [[Uranium-238|<sup>238</sup>U]]
|-
| align="center"| [[Uranium-238|<sup>238</sup>U]]
| align="center"| U<sub>I</sub>
| align="center"| Uranium I
| align="center"| [[alpha decay|α]]
| align="center"| 4.468×10<sup>9</sup> a
| align="center"| 4.26975
| align="center"| [[Thorium-234|<sup>234</sup>Th]]
|-
| align="center"| [[Thorium-234|<sup>234</sup>Th]]
| align="center"| UX<sub>1</sub>
| align="center"| Uranium X<sub>1</sub>
| align="center"| [[beta decay|β<sup>−</sup>]]
| align="center"| 24.10 d
| align="center"| 0.273088
| align="center"| [[Protactinium-234|<sup>234m</sup>Pa]]
|-
| align="center"| [[Protactinium-234|<sup>234m</sup>Pa]]
| align="center"| UX<sub>2</sub>, Bv
| align="center"| Uranium X<sub>2</sub><br/>Brevium
| align="center"| [[Isomeric transition|IT]], 0.16%<br />[[beta decay|β<sup>−</sup>]], 99.84%
| align="center"| 1.159 min
| align="center"| 0.07392<br />2.268205
| align="center"| [[Protactinium-234|<sup>234</sup>Pa]]<br />[[Uranium-234|<sup>234</sup>U]]
|-
| align="center"| [[Protactinium-234|<sup>234</sup>Pa]]
| align="center"| UZ
| align="center"| Uranium Z
| align="center"| [[beta decay|β<sup>−</sup>]]
| align="center"| 6.70 h
| align="center"| 2.194285
| align="center"| [[Uranium-234|<sup>234</sup>U]]
|-
| align="center"| [[Uranium-234|<sup>234</sup>U]]
| align="center"| U<sub>II</sub>
| align="center"| Uranium II
| align="center"| [[alpha decay|α]]
| align="center"| 2.45×10<sup>5</sup> a
| align="center"| 4.8698
| align="center"| [[Thorium-230|<sup>230</sup>Th]]
|-
| align="center"| [[Thorium-230|<sup>230</sup>Th]]
| align="center"| Io
| align="center"| Ionium
| align="center"| [[alpha decay|α]]
| align="center"| 7.54×10<sup>4</sup> a
| align="center"| 4.76975
| align="center"| [[Radium-226|<sup>226</sup>Ra]]
|-
| align="center"| [[Radium-226|<sup>226</sup>Ra]]
| align="center"| Ra
| align="center"| Radium
| align="center"| [[alpha decay|α]]
| align="center"| 1600 a
| align="center"| 4.87062
| align="center"| [[radon-222|<sup>222</sup>Rn]]
|-
| align="center"| [[radon-222|<sup>222</sup>Rn]]
| align="center"| Rn
| align="center"| Radon,<br/>Radium Emanation
| align="center"| [[alpha decay|α]]
| align="center"| 3.8235 d
| align="center"| 5.59031
| align="center"| [[Polonium-218|<sup>218</sup>Po]]
|-
| align="center"| [[Polonium-218|<sup>218</sup>Po]]
| align="center"| RaA
| align="center"| Radium A
| align="center"| [[alpha decay|α]], 99.980%<br />[[beta decay|β<sup>−</sup>]], 0.020%
| align="center"| 3.098 min
| align="center"| 6.11468<br />0.259913
| align="center"| [[Lead-214|<sup>214</sup>Pb]]<br />[[Astatine-218|<sup>218</sup>At]]
|-
| align="center"| [[Astatine-218|<sup>218</sup>At]]
| align="center"| 
| align="center"| 
| align="center"| [[alpha decay|α]], 100%<br />[[beta decay|β<sup>−</sup>]]
| align="center"| 1.28 s
| align="center"| 6.874<br />2.881314
| align="center"| [[Bismuth-214|<sup>214</sup>Bi]]<br />[[Radon-218|<sup>218</sup>Rn]]
|-
| align="center"| [[Radon-218|<sup>218</sup>Rn]]
| align="center"| 
| align="center"| 
| align="center"| [[alpha decay|α]]
| align="center"| 35 ms
| align="center"| 7.26254
| align="center"| [[Polonium-214|<sup>214</sup>Po]]
|-
| align="center"| [[Lead-214|<sup>214</sup>Pb]]
| align="center"| RaB
| align="center"| Radium B
| align="center"| [[beta decay|β<sup>−</sup>]]
| align="center"| 26.8 min
| align="center"| 1.019237
| align="center"| [[Bismuth-214|<sup>214</sup>Bi]]
|-
| align="center"| [[Bismuth-214|<sup>214</sup>Bi]]
| align="center"| RaC	
| align="center"| Radium C
| align="center"| [[beta decay|β<sup>−</sup>]], 99.979%<br />[[alpha decay|α]], 0.021%
| align="center"| 19.9 min
| align="center"| 3.269857<br />5.62119
| align="center"| [[Polonium-214|<sup>214</sup>Po]]<br />[[Thallium-210|<sup>210</sup>Tl]]
|-
| align="center"| [[Polonium-214|<sup>214</sup>Po]]
| align="center"| RaC'
| align="center"| Radium C'
| align="center"| [[alpha decay|α]]
| align="center"| 164.3 μs
| align="center"| 7.83346
| align="center"| [[Lead-210|<sup>210</sup>Pb]]
|-
| align="center"| [[Thallium-210|<sup>210</sup>Tl]]
| align="center"| RaC"
| align="center"| Radium C"
| align="center"| [[beta decay|β<sup>−</sup>]]<br />[[Beta-delayed neutron emission|β<sup>−</sup>n]], 0.009%
| align="center"| 1.3 min
| align="center"| 5.48213<br />0.296
| align="center"| [[Lead-210|<sup>210</sup>Pb]]<br />[[Lead-209|<sup>209</sup>Pb]] (from neptunium series)
|-
| align="center"| [[Lead-210|<sup>210</sup>Pb]]
| align="center"| RaD
| align="center"| Radium D
| align="center"| [[beta decay|β<sup>−</sup>]], 100%<br />[[alpha decay|α]], 1.9×10<sup>−6</sup>%
| align="center"| 22.20 a
| align="center"| 0.063487<br />3.7923
| align="center"| [[Bismuth-210|<sup>210</sup>Bi]]<br />[[Mercury-206|<sup>206</sup>Hg]]
|-
| align="center"| [[Bismuth-210|<sup>210</sup>Bi]]
| align="center"| RaE
| align="center"| Radium E	
| align="center"| [[beta decay|β<sup>−</sup>]], 100%<br />[[alpha decay|α]], 1.32×10<sup>−4</sup>%
| align="center"| 5.012 d
| align="center"| 1.161234<br />5.03647
| align="center"| [[Polonium-210|<sup>210</sup>Po]]<br />[[Thallium-206|<sup>206</sup>Tl]]
|-
| align="center"| [[Polonium-210|<sup>210</sup>Po]]
| align="center"| RaF
| align="center"| Radium F
| align="center"| [[alpha decay|α]]
| align="center"| 138.376 d
| align="center"| 5.03647
| align="center"| [[Lead-206|<sup>206</sup>Pb]]
|-
| align="center"| [[Mercury-206|<sup>206</sup>Hg]]
| align="center"| 
| align="center"| 
| align="center"| [[beta decay|β<sup>−</sup>]]
| align="center"| 8.32 min
| align="center"| 1.307649
| align="center"| [[Thallium-206|<sup>206</sup>Tl]]
|-
| align="center"| [[Thallium-206|<sup>206</sup>Tl]]
| align="center"| RaE"
| align="center"| Radium E"
| align="center"| [[beta decay|β<sup>−</sup>]]
| align="center"| 4.202 min
| align="center"| 1.5322211
| align="center"| [[Lead-206|<sup>206</sup>Pb]]
|-
| align="center"| [[Lead-206|<sup>206</sup>Pb]]
| align="center"| RaG<ref>{{Cite journal|last=Kuhn|first=W.|date=1929|title=LXVIII. Scattering of thorium C" γ-radiation by radium G and ordinary lead|url=https://doi.org/10.1080/14786441108564923|journal=The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science|volume=8|issue=52|pages=628|doi=10.1080/14786441108564923|issn=1941-5982|url-access=subscription}}</ref>
| align="center"| Radium G
| align="center"| stable
| align="center"| -
| align="center"| -
| align="center"| -
|}
{{reflist|group="RS"}}

=== Actinium series ===
The 4n+3 chain of [[uranium-235]] is commonly called the "actinium series" or "actinium cascade". Beginning with the naturally-occurring isotope uranium-235, this decay series includes the following elements:  actinium, [[astatine]], [[bismuth]], [[francium]], [[lead]], [[polonium]], [[protactinium]], radium, radon, [[thallium]], and [[thorium]]. All are present, at least transiently, in any sample containing uranium-235, whether metal, compound, ore, or mineral. This series terminates with the stable isotope [[lead-207]].
[[Image:Decay Chain of Actinium.svg|thumb|right|300px|alt=Actinium series|([[commons:File:Decay scheme U235.png|More detailed graphic]])]]

In the early Solar System this chain went back to <sup>247</sup>Cm. This manifests itself today as variations in <sup>235</sup>U/<sup>238</sup>U ratios, since [[curium]] and uranium have noticeably different chemistries and would have separated differently.<ref name=Davis/><ref>{{cite journal |last1=Tsaletka |first1=R. |last2=Lapitskii |first2=A. V. |date=1960 |title=Occurrence of the Transuranium Elements in Nature |url=https://www.russchemrev.org/RCR1264pdf |journal=Russian Chemical Reviews |volume=29 |issue=12 |pages=684–689 |doi= 10.1070/RC1960v029n12ABEH001264|bibcode=1960RuCRv..29..684T |access-date=20 January 2024}}</ref>

The total energy released from uranium-235 to lead-207, including the energy lost to neutrinos, is 46.4&nbsp;MeV.

{| class="wikitable" style="margin:auto; text-align:center;"
!rowspan=2|Nuclide
!colspan=2|Historic name
!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-251|<sup>251</sup>Cf]]
| 
| 
| [[alpha decay|α]]
| 900.6&nbsp;a
| 6.176
| <sup>247</sup>Cm
|-
|[[Curium-247|<sup>247</sup>Cm]]
|
|
|α
|1.56×10<sup>7</sup> a
|5.353
|<sup>243</sup>Pu
|-
|[[Plutonium-243|<sup>243</sup>Pu]]
|
| 
| [[beta decay|β<sup>&minus;</sup>]]
| 4.95556&nbsp;h
| 0.579
| <sup>243</sup>Am
|-
| [[Americium-243|<sup>243</sup>Am]]
| 
| 
| α
| 7388&nbsp;a
| 5.439
| <sup>239</sup>Np
|-
| [[Neptunium-239|<sup>239</sup>Np]]
| 
| 
| β<sup>&minus;</sup>
| 2.3565&nbsp;d
| 0.723
| <sup>239</sup>Pu
|-
| [[Plutonium-239|<sup>239</sup>Pu]]
| 
| 
| α
| align="center"| 2.41×10<sup>4</sup> a
| align="center"| 5.244
| align="center"| <sup>235</sup>U
|-
| align="center"| <sup>235</sup>U
| align="center"| AcU
| align="center"| Actino-uranium
| align="center"|  α
| align="center"| 7.04×10<sup>8</sup> a
| align="center"| 4.678
| align="center"| [[Thorium-231|<sup>231</sup>Th]]
|-
| align="center"| <sup>231</sup>Th
| align="center"| UY
| align="center"| Uranium Y
| align="center"| β<sup>−</sup>
| align="center"| 25.52 h
| align="center"| 0.391
| align="center"| [[Protactinium-231|<sup>231</sup>Pa]]
|-
| align="center"| <sup>231</sup>Pa
| align="center"| Pa
| align="center"| Protoactinium
| align="center"| α
| align="center"| 32760 a
| align="center"| 5.150
| align="center"| [[Actinium-227|<sup>227</sup>Ac]]
|-
| align="center"| <sup>227</sup>Ac
| align="center"| Ac
| align="center"| Actinium
| align="center"| β<sup>−</sup> 98.62% <br /> α 1.38%
| align="center"| 21.772 a
| align="center"| 0.045 <br /> 5.042
| align="center"| [[Thorium-227|<sup>227</sup>Th]] <br /> [[Francium-223|<sup>223</sup>Fr]]
|-
| align="center"| <sup>227</sup>Th
| align="center"| RdAc
| align="center"| Radioactinium
| align="center"|  α
| align="center"| 18.68 d
| align="center"| 6.147
| align="center"| [[Radium-223|<sup>223</sup>Ra]]
|-
| align="center"| <sup>223</sup>Fr
| align="center"| AcK
| align="center"| Actinium K
| align="center"|  β<sup>−</sup> 99.994% <br /> α 0.006%
| align="center"| 22.00 min
| align="center"| 1.149 <br /> 5.340
| align="center"| <sup>223</sup>Ra <br /> [[Astatine-219|<sup>219</sup>At]]
|-
| align="center"| <sup>223</sup>Ra
| align="center"| AcX
| align="center"| Actinium X
| align="center"|  α
| align="center"| 11.43 d
| align="center"| 5.979
| align="center"| [[Radon-219|<sup>219</sup>Rn]]
|-
| align="center"| <sup>219</sup>At
| align="center"|
| align="center"|
| align="center"|  α 97.00% <br /> β<sup>−</sup> 3.00%
| align="center"| 56 s
| align="center"| 6.275 <br /> 1.700
| align="center"| [[Bismuth-215|<sup>215</sup>Bi]] <br /> <sup>219</sup>Rn
|-
| align="center"| <sup>219</sup>Rn
| align="center"| An
| align="center"| Actinon,<br />Actinium Emanation
| align="center"|  α
| align="center"| 3.96 s
| align="center"| 6.946
| align="center"| [[Polonium-215|<sup>215</sup>Po]]
|-
| align="center"| <sup>215</sup>Bi
| align="center"|
| align="center"|
| align="center"|  β<sup>−</sup>
| align="center"| 7.6 min
| align="center"| 2.250  	
| align="center"| <sup>215</sup>Po
|-
| align="center"| <sup>215</sup>Po
| align="center"| AcA
| align="center"| Actinium A
| align="center"|  α 99.99977% <br />  β<sup>−</sup> 0.00023%
| align="center"| 1.781 ms
| align="center"| 7.527 <br /> 0.715
| align="center"| [[Lead-211|<sup>211</sup>Pb]] <br /> [[Astatine-215|<sup>215</sup>At]]
|-
| align="center"| <sup>215</sup>At
| align="center"|
| align="center"|
| align="center"|  α
| align="center"| 0.1 ms
| align="center"| 8.178
| align="center"| [[Bismuth-211|<sup>211</sup>Bi]]
|-
| align="center"| <sup>211</sup>Pb
| align="center"| AcB
| align="center"| Actinium B
| align="center"|  β<sup>−</sup>
| align="center"| 36.1 min
| align="center"| 1.367
| align="center"| <sup>211</sup>Bi
|-
| align="center"| <sup>211</sup>Bi
| align="center"| AcC
| align="center"| Actinium C
| align="center"|  α 99.724% <br />  β<sup>−</sup> 0.276%
| align="center"| 2.14 min
| align="center"| 6.751 <br /> 0.575
| align="center"| [[Thallium-207|<sup>207</sup>Tl]] <br /> [[Polonium-211|<sup>211</sup>Po]]
|-
| align="center"| <sup>211</sup>Po
| align="center"| AcC'
| align="center"| Actinium C'
| align="center"|  α
| align="center"| 516 ms
| align="center"| 7.595
| align="center"| [[Lead-207|<sup>207</sup>Pb]]
|-
| align="center"| <sup>207</sup>Tl
| align="center"| AcC"
| align="center"| Actinium C"
| align="center"| β<sup>−</sup>
| align="center"| 4.77 min
| align="center"| 1.418
| align="center"| <sup>207</sup>Pb
|-
| align="center"| <sup>207</sup>Pb
| align="center"| AcD
| align="center"| Actinium D
| align="center"| .
| align="center"| stable
| align="center"| .
| align="center"| .
|}