Physics:Isotopes of tantalum

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Short description: List of nuclides having atomic number 73 but different mass numbers

Natural tantalum (73Ta) consists of two stable isotopes: 181Ta (99.988%) and The element Chemistry:Ta does not exist. (0.012%).

There are also 35 known artificial radioisotopes, the longest-lived of which are 179Ta with a half-life of 1.82 years, 182Ta with a half-life of 114.43 days, 183Ta with a half-life of 5.1 days, and 177Ta with a half-life of 56.56 hours. All other isotopes have half-lives under a day, most under an hour. There are also numerous isomers, the most stable of which (other than 180mTa) is 178m1Ta with a half-life of 2.36 hours. All isotopes and nuclear isomers of tantalum are either radioactive or observationally stable, meaning that they are predicted to be radioactive but no actual decay has been observed.

Tantalum has been proposed as a "salting" material for nuclear weapons (cobalt is another, better-known salting material). A jacket of 181Ta, irradiated by the intense high-energy neutron flux from an exploding thermonuclear weapon, would transmute into the radioactive isotope The element Chemistry:Ta does not exist. with a half-life of 114.43 days and produce approximately 1.12 MeV of gamma radiation, significantly increasing the radioactivity of the weapon's fallout for several months. Such a weapon is not known to have ever been built, tested, or used.[1] While the conversion factor from absorbed dose (measured in Grays) to effective dose (measured in Sievert) for gamma rays is 1 while it is 50 for alpha radiation (i.e., a gamma dose of 1 Gray is equivalent to 1 Sievert whereas an alpha dose of 1 Gray is equivalent to 50 Sievert), gamma rays are only attenuated by shielding, not stopped. As such, alpha particles require incorporation to have an effect while gamma rays can have an effect via mere proximity. In military terms, this allows a gamma ray weapon to deny an area to either side as long as the dose is high enough, whereas radioactive contamination by alpha emitters which do not release significant amounts of gamma rays can be counteracted by ensuring the material is not incorporated.

List of isotopes

Nuclide
[n 1] 		Z N Isotopic mass (u)
[n 2][n 3] 		Half-life
[n 4] 		Decay
mode
[n 5] 		Daughter
isotope
[n 6][n 7] 		Spin and
parity
[n 8][n 4] 		Physics:Natural abundance (mole fraction)
Excitation energy[n 4] Normal proportion Range of variation
The element Chemistry:Ta does not exist. 73 82 154.97459(54)# 2.9+1.5
−1.1 ms[2] 		p 154Hf (11/2−)
The element Chemistry:Ta does not exist. ~323 keV 12+4
−3 μs[3] 		p 154Hf 11/2−?
The element Chemistry:Ta does not exist.[4] 73 83 155.97230(43)# 106(4) ms p (71%) 155Hf (2−)
β+ (29%) 156Hf
The element Chemistry:Ta does not exist. 102(7) keV 0.36(4) s p 155Hf 9+
The element Chemistry:Ta does not exist. 73 84 156.96819(22) 10.1(4) ms α (91%) 153Lu 1/2+
β+ (9%) 157Hf
The element Chemistry:Ta does not exist. 22(5) keV 4.3(1) ms 11/2−
The element Chemistry:Ta does not exist. 1593(9) keV 1.7(1) ms α 153Lu (25/2−)
The element Chemistry:Ta does not exist. 73 85 157.96670(22)# 49(8) ms α (96%) 154Lu (2−)
β+ (4%) 158Hf
The element Chemistry:Ta does not exist. 141(9) keV 36.0(8) ms α (93%) 154Lu (9+)
IT 158Ta
β+ 158Hf
The element Chemistry:Ta does not exist. 73 86 158.963018(22) 1.04(9) s β+ (66%) 159Hf (1/2+)
α (34%) 155Lu
The element Chemistry:Ta does not exist. 64(5) keV 514(9) ms α (56%) 155Lu (11/2−)
β+ (44%) 159Hf
The element Chemistry:Ta does not exist. 73 87 159.96149(10) 1.70(20) s α 156Lu (2#)−
β+ 160Hf
The element Chemistry:Ta does not exist. 310(90)# keV 1.55(4) s β+ (66%) 160Hf (9)+
α (34%) 156Lu
The element Chemistry:Ta does not exist. 73 88 160.95842(6)# 3# s β+ (95%) 161Hf 1/2+#
α (5%) 157Lu
The element Chemistry:Ta does not exist. 50(50)# keV 2.89(12) s 11/2−#
The element Chemistry:Ta does not exist. 73 89 161.95729(6) 3.57(12) s β+ (99.92%) 162Hf 3+#
α (.073%) 158Lu
The element Chemistry:Ta does not exist. 73 90 162.95433(4) 10.6(18) s β+ (99.8%) 163Hf 1/2+#
α (.2%) 159Lu
The element Chemistry:Ta does not exist. 73 91 163.95353(3) 14.2(3) s β+ 164Hf (3+)
The element Chemistry:Ta does not exist. 73 92 164.950773(19) 31.0(15) s β+ 165Hf 5/2−#
The element Chemistry:Ta does not exist. 60(30) keV 9/2−#
The element Chemistry:Ta does not exist. 73 93 165.95051(3) 34.4(5) s β+ 166Hf (2)+
The element Chemistry:Ta does not exist. 73 94 166.94809(3) 1.33(7) min β+ 167Hf (3/2+)
The element Chemistry:Ta does not exist. 73 95 167.94805(3) 2.0(1) min β+ 168Hf (2−,3+)
The element Chemistry:Ta does not exist. 73 96 168.94601(3) 4.9(4) min β+ 169Hf (5/2+)
The element Chemistry:Ta does not exist. 73 97 169.94618(3) 6.76(6) min β+ 170Hf (3)(+#)
The element Chemistry:Ta does not exist. 73 98 170.94448(3) 23.3(3) min β+ 171Hf (5/2−)
The element Chemistry:Ta does not exist. 73 99 171.94490(3) 36.8(3) min β+ 172Hf (3+)
The element Chemistry:Ta does not exist. 73 100 172.94375(3) 3.14(13) h β+ 173Hf 5/2−
The element Chemistry:Ta does not exist. 73 101 173.94445(3) 1.14(8) h β+ 174Hf 3+
The element Chemistry:Ta does not exist. 73 102 174.94374(3) 10.5(2) h β+ 175Hf 7/2+
The element Chemistry:Ta does not exist. 73 103 175.94486(3) 8.09(5) h β+ 176Hf (1)−
The element Chemistry:Ta does not exist. 103.0(10) keV 1.1(1) ms IT 176Ta (+)
The element Chemistry:Ta does not exist. 1372.6(11)+X keV 3.8(4) µs (14−)
The element Chemistry:Ta does not exist. 2820(50) keV 0.97(7) ms (20−)
The element Chemistry:Ta does not exist. 73 104 176.944472(4) 56.56(6) h β+ 177Hf 7/2+
The element Chemistry:Ta does not exist. 73.36(15) keV 410(7) ns 9/2−
The element Chemistry:Ta does not exist. 186.15(6) keV 3.62(10) µs 5/2−
The element Chemistry:Ta does not exist. 1355.01(19) keV 5.31(25) µs 21/2−
The element Chemistry:Ta does not exist. 4656.3(5) keV 133(4) µs 49/2−
The element Chemistry:Ta does not exist. 73 105 177.945778(16) 9.31(3) min β+ 178Hf 1+
The element Chemistry:Ta does not exist. 100(50)# keV 2.36(8) h β+ 178Hf (7)−
The element Chemistry:Ta does not exist. 1570(50)# keV 59(3) ms (15−)
The element Chemistry:Ta does not exist. 3000(50)# keV 290(12) ms (21−)
The element Chemistry:Ta does not exist. 73 106 178.9459295(23) 1.82(3) y EC 179Hf 7/2+
The element Chemistry:Ta does not exist. 30.7(1) keV 1.42(8) µs (9/2)−
The element Chemistry:Ta does not exist. 520.23(18) keV 335(45) ns (1/2)+
The element Chemistry:Ta does not exist. 1252.61(23) keV 322(16) ns (21/2−)
The element Chemistry:Ta does not exist. 1317.3(4) keV 9.0(2) ms IT 179Ta (25/2+)
The element Chemistry:Ta does not exist. 1327.9(4) keV 1.6(4) µs (23/2−)
The element Chemistry:Ta does not exist. 2639.3(5) keV 54.1(17) ms (37/2+)
The element Chemistry:Ta does not exist. 73 107 179.9474648(24) 8.152(6) h EC (86%) 180Hf 1+
β− (14%) 180W
The element Chemistry:Ta does not exist. 77.1(8) keV Observationally stable[n 9][n 10] 9− 1.2(2)×10−4
The element Chemistry:Ta does not exist. 1452.40(18) keV 31.2(14) µs 15−
The element Chemistry:Ta does not exist. 3679.0(11) keV 2.0(5) µs (22−)
The element Chemistry:Ta does not exist. 4171.0+X keV 17(5) µs (23, 24, 25)
The element Chemistry:Ta does not exist. 73 108 180.9479958(20) Observationally stable[n 11] 7/2+ 0.99988(2)
The element Chemistry:Ta does not exist. 6.238(20) keV 6.05(12) µs 9/2−
The element Chemistry:Ta does not exist. 615.21(3) keV 18(1) µs 1/2+
The element Chemistry:Ta does not exist. 1485(3) keV 25(2) µs 21/2−
The element Chemistry:Ta does not exist. 2230(3) keV 210(20) µs 29/2−
The element Chemistry:Ta does not exist. 73 109 181.9501518(19) 114.43(3) d β− 182W 3−
The element Chemistry:Ta does not exist. 16.263(3) keV 283(3) ms IT 182Ta 5+
The element Chemistry:Ta does not exist. 519.572(18) keV 15.84(10) min 10−
The element Chemistry:Ta does not exist. 73 110 182.9513726(19) 5.1(1) d β− 183W 7/2+
The element Chemistry:Ta does not exist. 73.174(12) keV 107(11) ns 9/2−
The element Chemistry:Ta does not exist. 73 111 183.954008(28) 8.7(1) h β− 184W (5−)
The element Chemistry:Ta does not exist. 73 112 184.955559(15) 49.4(15) min β− 185W (7/2+)#
The element Chemistry:Ta does not exist. 1308(29) keV >1 ms (21/2−)
The element Chemistry:Ta does not exist. 73 113 185.95855(6) 10.5(3) min β− 186W (2−,3−)
The element Chemistry:Ta does not exist. 1.54(5) min
The element Chemistry:Ta does not exist. 73 114 186.96053(21)# 2# min
[>300 ns] 		β− 187W 7/2+#
The element Chemistry:Ta does not exist. 73 115 187.96370(21)# 20# s
[>300 ns] 		β− 188W
The element Chemistry:Ta does not exist. 73 116 188.96583(32)# 3# s
[>300 ns] 		7/2+#
The element Chemistry:Ta does not exist. 73 117 189.96923(43)# 0.3# s
  1. ↑ mTa – Excited nuclear isomer.
  2. ↑ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
  3. ↑ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
  4. ↑ 4.0 4.1 4.2 # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  5. ↑ Modes of decay:
    EC: Electron capture
    IT: Isomeric transition


    p: Proton emission
  6. ↑ Bold italics symbol as daughter – Daughter product is nearly stable.
  7. ↑ Bold symbol as daughter – Daughter product is stable.
  8. ↑ ( ) spin value – Indicates spin with weak assignment arguments.
  9. ↑ Only known observationally stable nuclear isomer, believed to decay by isomeric transition to 180Ta, β− decay to 180W, or electron capture to 180Hf with a half-life over 2.9×1017 years[5]; also theorized to undergo α decay to 176Lu
  10. ↑ One of the few (observationally) stable odd-odd nuclei
  11. ↑ Believed to undergo α decay to 177Lu

Tantalum-180m

The nuclide The element Chemistry:Ta does not exist. (m denotes a metastable state) has sufficient energy to decay in three ways: isomeric transition to the ground state of The element Chemistry:Ta does not exist., beta decay to [[Chemistry:Tungsten|The element Chemistry:W does not exist.]], and electron capture to [[Chemistry:Hafnium|The element Chemistry:Hf does not exist.]]. However, no radioactivity from any decay mode of this nuclear isomer has ever been observed. As of 2023, the half-life of 180mTa is calculated from experimental observation to be at least 2.9×1017 (290 quadrillion) years.[5][6][7] The very slow decay of The element Chemistry:Ta does not exist. is attributed to its high spin (9 units) and the low spin of lower-lying states. Gamma or beta decay would require many units of angular momentum to be removed in a single step, so that the process would be very slow.[8]

The very unusual nature of 180mTa is that the ground state of this isotope is less stable than the isomer. This phenomenon is exhibited in bismuth-210m (210mBi) and americium-242m (242mAm), among other nuclides. The element Chemistry:Ta does not exist. has a half-life of only 8 hours. The element Chemistry:Ta does not exist. is the only naturally occurring nuclear isomer (excluding radiogenic and cosmogenic short-living nuclides). It is also the rarest primordial nuclide in the Universe observed for any element that has any stable isotopes. In an s-process stellar environment with a thermal energy kBT = 26 keV (i.e. a temperature of 300 million kelvin), the nuclear isomers are expected to be fully thermalized, meaning that 180Ta rapidly transitions between spin states and its overall half-life is predicted to be 11 hours.[9]

It is one of only five stable nuclides to have both an odd number of protons and an odd number of neutrons, the other four stable odd-odd nuclides being 2H, 6Li, 10B and 14N.[10]

References

  1. ↑ D. T. Win; M. Al Masum (2003). "Weapons of Mass Destruction". Assumption University Journal of Technology 6 (4): 199–219. http://www.journal.au.edu/au_techno/2003/apr2003/aujt6-4_article07.pdf. 
  2. ↑ Page, R. D.; Bianco, L.; Darby, I. G.; Uusitalo, J.; Joss, D. T.; Grahn, T.; Herzberg, R.-D.; Pakarinen, J. et al. (26 June 2007). "α decay of Re 159 and proton emission from Ta 155" (in en). Physical Review C 75 (6): 061302. doi:10.1103/PhysRevC.75.061302. ISSN 0556-2813. Bibcode: 2007PhRvC..75f1302P. https://openresearch.surrey.ac.uk/view/delivery/44SUR_INST/12139605080002346/13140305300002346. 
  3. ↑ Uusitalo, J.; Davids, C. N.; Woods, P. J.; Seweryniak, D.; Sonzogni, A. A.; Batchelder, J. C.; Bingham, C. R.; Davinson, T. et al. (1 June 1999). "Proton emission from the closed neutron shell nucleus 155 Ta" (in en). Physical Review C 59 (6): R2975–R2978. doi:10.1103/PhysRevC.59.R2975. ISSN 0556-2813. Bibcode: 1999PhRvC..59.2975U. https://journals.aps.org/prc/pdf/10.1103/PhysRevC.59.R2975. Retrieved 12 June 2023. 
  4. ↑ Darby, I. G.; Page, R. D.; Joss, D. T.; Bianco, L.; Grahn, T.; Judson, D. S.; Simpson, J.; Eeckhaudt, S. et al. (20 June 2011). "Precision measurements of proton emission from the ground states of Ta 156 and Re 160" (in en). Physical Review C 83 (6): 064320. doi:10.1103/PhysRevC.83.064320. ISSN 0556-2813. Bibcode: 2011PhRvC..83f4320D. https://journals.aps.org/prc/pdf/10.1103/PhysRevC.83.064320. Retrieved 21 June 2023. 
  5. ↑ 5.0 5.1 Arnquist, I. J.; Avignone III, F. T.; Barabash, A. S.; Barton, C. J.; Bhimani, K. H.; Blalock, E.; Bos, B.; Busch, M. et al. (13 October 2023). "Constraints on the Decay of 180mTa". Phys. Rev. Lett. 131 (15): 152501. doi:10.1103/PhysRevLett.131.152501. 
  6. ↑ Conover, Emily (2016-10-03). "Rarest nucleus reluctant to decay". https://www.sciencenews.org/article/rarest-nucleus-reluctant-decay. 
  7. ↑ Lehnert, Björn; Hult, Mikael; Lutter, Guillaume; Zuber, Kai (2017). "Search for the decay of nature's rarest isotope 180mTa". Physical Review C 95 (4): 044306. doi:10.1103/PhysRevC.95.044306. Bibcode: 2017PhRvC..95d4306L. 
  8. ↑ Quantum mechanics for engineers Leon van Dommelen, Florida State University
  9. ↑ P. Mohr, F. Kaeppeler, and R. Gallino (2007). "Survival of Nature's Rarest Isotope 180Ta under Stellar Conditions". Phys. Rev. C 75: 012802. doi:10.1103/PhysRevC.75.012802. 
  10. ↑ Various (2002). Lide, David R.. ed. Handbook of Chemistry & Physics (88th ed.). CRC. ISBN 978-0-8493-0486-6. OCLC 179976746. http://www.hbcpnetbase.com/. Retrieved 2008-05-23. 

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