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Isotopes of Thorium

List, data and properties of all known isotopes of Thorium as well as radioactive decay products and intermediate products.

 

Thorium isotopes

All atomic nuclei of the chemical element thorium are summarized under thorium isotopes; these all consist of an atomic nucleus with 90 protons and, in the uncharged state, 90 electrons. The difference between the individual thorium isotopes is based on the number of neutrons in the nucleus.

Terrestrial thorium deposits consist of practically 99.98% of the nuclide 232Th and 0 .02% from 230Th; in addition, the 4 isotopes 227Th, 228Th, 231Th and 234Th and 234 are found in small traces and as intermediate products of radioactive decay processes. sup>Th.

The relative atomic mass is given as 232.0377(4) u.

 

Isotope Table: Thorium

 

Atomic Properties

Isotope
Nuclide
ZANNameAtomic Mass
[Nuclear Mass]
{Mass Excess}
Spin I
(h/2π)
μParent
123456789
208Th90208118Thorium-208208.01791(4) u
[207.9685442 u]
{16.68306 MeV}
0+
209Th90209119Thorium-209209.01757(15) u
[208.9682042 u]
{16.36635 MeV}
(13/2+)
210Th90210120Thorium-210210.015093(20) u
[209.9657272 u]
{14.05904 MeV}
0+
211Th90211121Thorium-211211.01493(8) u
[210.9655642 u]
{13.90721 MeV}
212Th90212122Thorium-212212.013001(11) u
[211.9636352 u]
{12.11035 MeV}
0+
213Th90213123Thorium-213213.013011(10) u
[212.9636452 u]
{12.11967 MeV}
(5/2-)217U
214Th90214124Thorium-214214.011481(11) u
[213.9621152 u]
{10.69448 MeV}
0+218U
214mTh90214124Thorium-214m214.011481(11) u
[213.9621152 u]
{10.69448 MeV}
(8+)
215Th90215125Thorium-215215.011725(9) u
[214.9623592 u]
{10.92177 MeV}
(1/2-)219U
215mTh90215125Thorium-215m215.011725(9) u
[214.9623592 u]
{10.92177 MeV}
216Th90216126Thorium-216216.011056(13) u
[215.9616902 u]
{10.2986 MeV}
0+
216m1Th90216126Thorium-216m1216.011056(13) u
[215.9616902 u]
{10.2986 MeV}
8+
216m2Th90216126Thorium-216m2216.011056(13) u
[215.9616902 u]
{10.2986 MeV}
11-
216m3Th90216126Thorium-216m3216.011056(13) u
[215.9616902 u]
{10.2986 MeV}
(14+)
217Th90217127Thorium-217217.013103(11) u
[216.9637372 u]
{12.20537 MeV}
(9/2+)
217m1Th90217127Thorium-217m1217.013103(11) u
[216.9637372 u]
{12.20537 MeV}
(15/2-)
218Th90218128Thorium-218218.013276(11) u
[217.9639102 u]
{12.36651 MeV}
0+222U
219Th90219129Thorium-219219.01554(5) u
[218.9661742 u]
{14.47542 MeV}
(9/2+)223U
220Th90220130Thorium-220220.015748(24) u
[219.9663822 u]
{14.66917 MeV}
0+224U
221Th90221131Thorium-221221.018186(9) u
[220.9688202 u]
{16.94015 MeV}
(7/2+)225U
222Th90222132Thorium-222222.018468(13) u
[221.9691022 u]
{17.20283 MeV}
0+226U
223Th90223133Thorium-223223.020812(10) u
[222.9714462 u]
{19.38625 MeV}
(5/2)+227U
224Th90224134Thorium-224224.021464(11) u
[223.9720982 u]
{19.99359 MeV}
0+228U
225Th90225135Thorium-225225.023951(5) u
[224.9745852 u]
{22.31021 MeV}
(3/2+)229U
226Th90226136Thorium-226226.024904(5) u
[225.9755382 u]
{23.19793 MeV}
0+230U
226Ac
226Pa
227Th90227137Thorium-227227.0277026(22) u
[226.9783368 u]
{25.80481 MeV}
(1/2+)231U
227Ac
227Pa
228Th90228138Thorium-228228.0287398(19) u
[227.979374 u]
{26.77095 MeV}
0+232U
228Ac
228Pa
229Th90229139Thorium-229229.0317614(26) u
[228.9823956 u]
{29.58555 MeV}
5/2++ 0.46(4)233U
229Ac
229mTh90229139Thorium-229m229.0317614(26) u
[228.9823956 u]
{29.58555 MeV}
3/2+
230Th90230140Thorium-230230.03313(2) u
[229.9837642 u]
{30.8604 MeV}
0+234U
230Ac
230Pa
231Th90231141Thorium-231231.0363029(13) u
[230.9869371 u]
{33.81593 MeV}
5/2+235U
231Ac
232Th90232142Thorium-232232.03806(2) u
[231.9886942 u]
{35.45266 MeV}
0+236U
232Ac
232Pa
233Th90233143Thorium-233233.0415802(15) u
[232.9922144 u]
{38.73171 MeV}
1/2+233Ac
234Th90234144Thorium-234234.0435999(28) u
[233.9942341 u]
{40.61305 MeV}
0+238U
234Ac
235Th90235145Thorium-235235.047255(14) u
[234.9978892 u]
{44.01775 MeV}
(1/2+)
236Th90236146Thorium-236236.049657(15) u
[236.0002912 u]
{46.2552 MeV}
0+
237Th90237147Thorium-237237.053629(17) u
[237.0042632 u]
{49.95509 MeV}
(5/2+)
238Th90238148Thorium-238238.05639(30) u
[238.0070242 u]
{52.52695 MeV}
0+

 

Radioactive Decay Properties

IsotopeRadioactive DecayAEExtern
Half-lifeDecay ModeProbabilityEnergy
1101112131415
Th-2081.7 msα → 204Ra100 %8.20(3) MeVAL
Th-2092.5 msα → 205Ra8.10(14) MeVAL
Th-2101.6(4) msα → 206Ra
EC/β+210Ac
99 %
ca. 1 %
8.069(6) MeV
5.27(6) MeV
AL
Th-21137 msα → 207Ra
&epsilon → 211Ac
?
?
7.94(5) MeV
6.71(9) MeV
AL
Th-21231.7(13) msα → 208Ra
EC/β+212Ac
ca. 99.7 %
ca. 0.3 %
7.958(5) MeV
4.83(5) MeV
AL
Th-213144(21) msα → 209Ra≤ 100 %7.837(7) MeVAL
Th-21487(10) msα → 210Ra100 %7.827(5) MeVAL
Th-214m1.24(12) μsIso → 214Th100 %2181.0(27) keV
Th-2151.2(2) sα → 211Ra100 %7.665(4) MeVAL
Th-215m0.77(6) μsIso → 215Th100 %1421.3+x keV
Th-21626.0(2) msα → 212Ra≤ 100 %8.072(4) MeVAL
Th-216m1134(4) μsα → 212Ra2.8(9) %2040(9) keV
Th-216m20.58(3) μs2646.8(1) keV
Th-216m30.74(7) μs3681.4(7) keV
Th-2170.252(4) msα → 213Ra100 %9.435(4) MeVAL
Th-217m10.141(50) msIso → 217Th100 %673.3(1) keVAL
Th-218117(9) nsα → 214Ra100 %9.849(9) MeVAL
Th-2191.05(3) μsα → 215Ra100 %9.51(5) MeVAL
Th-2209.7(6) μsα → 216Ra
EC → 220Ac
≤ 100 %
<< 1 %
8.953(20) MeV
0.925(23) MeV
AL
Th-2211.74(3) msα → 217Ra100 %8.626(4) MeVAL
Th-2222.24(3) msα → 218Ra100 %8.127(5) MeVAL
Th-2230.60(2) sα → 219Ra100 %7.567(4) MeVAL
Th-2241.04(2) sα → 220Ra100 %7.299(6) MeVAL
Th-2258.75(4) minα → 221Ra
EC → 225Ac
ca. 90 %
ca. 10 %
6.9214(21) MeV
0.637(7) MeV
AL
Th-22630.57(10) minα → 222Ra100 %6.4525(10) MeVAL
Th-22718.697(7) dα → 223Ra100 %6.1466(1) MeVAL
Th-2281.9116(16) aα → 224Ra100 %5.52015(22) MeVAL
Th-2297880(120) aα → 225Ra100 %5.1676(10) MeVAL
Th-229m7(1) μsIso → 229Th0.00810(17) keV
Th-2307.54(3) × 104 aα → 226Ra
SF div
CD → 24Ne
ca. 100 %
<< 1 %
<< 1 %
4.7698(15) MeV

AL
Th-23125.52(1) hα → 227Ra
β-231Pa
<< 1 %
>> 99 %
4.2133(15) MeV
0.3915(15) MeV
AL
Th-2321.40(1) × 1010 aα → 228Ra
SF div
> 99 %
<< 1 %
4.0816(14) MeV
AL
Th-23321.83(4) minβ-233Pa100 %1.2422(11) MeVAL
Th-23424.10(3) dβ-234Pa100 %0.274(3) MeVAL
Th-2357.2(1) minβ-235Pa100 %1.729(19) MeVAL
Th-23637.3(15) minβ-236Pa100 %0.921(20) MeVAL
Th-2374.8(5) minβ-237Pa100 %2.427(21) MeVAL
Th-2389.4(20) minβ-238Pa100 %1.63(28) MeVAL

 

Notes (related to the columns):

1 - nuclide, isotope symbol.
2 - Z = number of protons (atomic number).
3 - Mass number A.
4 - N = number of neutrons.
5 - Identification of the Thorium isotope.
6 - Relative atomic mass of the Thorium isotope (isotopic mass including electrons) and the mass of the atomic nucleus in square brackets (nuclear mass, nuclide mass without electrons), each related to 12C = 12.00000 [2]. In addition, the mass excess is given in MeV.
7 - Nuclear spin I, unit: h/2π.
8 - Nuclear magnetic moment μmag.
9 - Source nuclides: Possible, assumed or actual source nuclides (mother nuclides, parent nuclides). If applicable, the corresponding decay modes can be found in the data for the respective starting nuclide.
10 - Decay: Half-live of the Thorium isotope (a = years; ; d = days; h = hours; min = minutes; s = seconds).
11 - Decay: type of decay into the respective daughter nuclides with n = neutron emission; p = proton emission; α = alpha decay; β- = beta minus decay with electron emission; EC = electron capture; β+ = positron emission; ε = β+ and/or EC; Iso = isomeric transition; CD = cluster decay; SF = spontaneous decay.
12 - Decay percentage in percent (%).
13 - Decay energy; Particle energy related to decay type.
14 - AE = Excitation energy for metastable nuclei.
15 - Other information and notes: AL = Adopted Levels (link to external data [1]).

Miscellaneous:

()- Numbers in brackets: uncertainty to represent the spread of the reported value.
~ - Theoretical values or systematic trends.
  - unlisted-: Nuclides that have already been mentioned in the literature but for some reason can no longer be found in the current nuclide tables because their discovery e.g. has not confirmed.

 

NMR active Thorium nuclides

Nuclide
quantity 1)
spin
Nuclear magnetic
moment
μ/μN
Gyromagnetic
ratio
107 rad T-1 s-1
Quadrupole
moment
Q fm-2
Resonant
frequency
v0 bei 1 T
Relative
sensitivity
H0 = const.
v0 = const. 2)
229Th

5/2+
+ 0,46(4)0,40311,0(6)1,400,00042
0,3843

1) Quantity Percentage of natural occurrence.

2) Related to 1H = 1,000.

 

Radiation Protection

According to the Radiation Protection Ordinance (StrlSchV 2018, Germany), the following values (columns 1 to 7) apply to the handling of Thorium radionuclides:

NuclideLimit ValueHASS limitSCDaughter NuclidesHalf-life
Th-226+107 Bq1000 Bq/g10 Bq cm-2Ra-222, Rn-218, Po-21430.6 min
Th-227104 Bq10 Bq/g0,1 Bq cm-218.7 d
Th-228+104 Bq0,1 Bq/g0,04 TBq0,1 Bq cm-2Ra-224, Rn-220, Po-216,
Pb-212, Bi-212, Tl-208,
Po-212
1.9 a
Th-229+103 Bq0,1 Bq/g0,01 TBq0,1 Bq cm-2Ra-225, Ac-225, Fr-221,
At-217, Bi-213, Tl-209,
Po-213, Pb-209
7300 a
Th-230104 Bq0,1 Bq/g0,1 Bq cm-275000 a
Th-231107 Bq1000 Bq/g10 TBq100 Bq cm-225.5 h
Th-232104 Bq10 Bq/g0,1 Bq cm-21.4 × 1010 a
Th234+105 Bq100 Bq/g2 TBq100 Bq cm-2Pa-234m, Pa-23424.1 d

(HASS = High-Activity Sealed Radioactive Sources; SC = surface contamination)

 

Literature Sources and References

Properties of the Thorium nucleides

[1] - NuDat: National Nuclear Data Center, Brookhaven National Laboratory, based on ENSDF and the Nuclear Wallet Cards.

[2] - G. Audi et. al.: The NUBASE evaluation of nuclear and decay properties. Nuclear Physics, (2003), DOI 10.1016/j.nuclphysa.2003.11.001.

[3] - Live Chart of Nuclides. Nuclear structure and decay data.

Thorium: NMR properties - 229Th-NMR

[4] - N. J. Stone: Table of nuclear magnetic dipole and electric quadrupole moments. Atomic Data and Nuclear Data Tables, (2005), DOI 10.1016/j.adt.2005.04.001.

[5] - Pekka Pyykkö: Year-2008 nuclear quadrupole moments. Molecular Physics, (2008), DOI 10.1080/00268970802018367.

[6] - Pekka Pyykkö: Year-2017 nuclear quadrupole moments. Molecular Physics, (2018), DOI 10.1080/00268976.2018.1426131.

[7] - N. J. Stone: Table of recommended nuclear magnetic dipole moments. IAEA, (2019).

More sources:

[8] - Isotopic abundances, atomic weights and isotopic masses: see respective keyword.

[9] - C. Fry, M. Thoennessen:
Discovery of actinium, thorium, protactinium, and uranium isotopes.
In: Atomic Data and Nuclear Data Tables, (2013), DOI 10.1016/j.adt.2012.03.002.

 


Category: Isotopes

Last update: 05.07.2020



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