Naturally occurring lanthanum (57La) is composed of one stable (139La) and one radioactive (138La) isotope, with the stable isotope, 139La, being the most abundant (99.91% natural abundance). There are 39 radioisotopes that have been characterized, with the most stable being 138La, with a half-life of 1.03×1011 years; 137La, with a half-life of 60,000 years and 140La, with a half-life of 1.6781 days. The remaining radioactive isotopes have half-lives that are less than a day and the majority of these have half-lives that are less than 1 minute. This element also has 12 nuclear isomers, the longest-lived of which is 132mLa, with a half-life of 24.3 minutes. Lighter isotopes mostly decay to isotopes of barium and heavy ones mostly decay to isotopes of cerium. 138La can decay to both.
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| Standard atomic weight Ar°(La) | ||||||||||||||||||||||||||||
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The isotopes of lanthanum range in atomic weight from 115.96 u (116La) to 154.96 u (155La).
List of isotopes
edit| Nuclide [n 1] |
Z | N | Isotopic mass (Da)[4] [n 2][n 3] |
Half-life[1] [n 4][n 5] |
Decay mode[1] [n 6] |
Daughter isotope [n 7][n 8] |
Spin and parity[1] [n 9][n 5] |
Natural abundance (mole fraction) | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Excitation energy[n 5] | Normal proportion[1] | Range of variation | |||||||||||||||||
| 116La[5] | 57 | 59 | 115.95701(35)# | 50(22) ms | p (~60%) | 115Ba | |||||||||||||
| β+ (~40%) | 116Ba | ||||||||||||||||||
| 116mLa[5] | 182 keV | 2.0+2.8 −0.8 μs |
IT | 116La | |||||||||||||||
| 117La[5] | 57 | 60 | 116.95033(22)# | 21.6(31) ms | p (94%) | 116Ba | (3/2+) | ||||||||||||
| β+ (6%) | 117Ba | ||||||||||||||||||
| 117mLa[5] | 192 keV | 3.9+1.9 −0.9 μs |
IT | 117La | (7/2−) | ||||||||||||||
| 120La | 57 | 63 | 119.93820(32)# | 2.8(2) s | β+ | 120Ba | 4+[6] | ||||||||||||
| β+, p (?%) | 119Cs | ||||||||||||||||||
| 121La | 57 | 64 | 120.93324(32)# | 5.3(2) s | β+ | 121Ba | 11/2−# | ||||||||||||
| 122La | 57 | 65 | 121.93071(32)# | 8.6(5) s | β+ | 122Ba | 2+[6] | ||||||||||||
| β+, p (?%) | 121Cs | ||||||||||||||||||
| 123La | 57 | 66 | 122.92630(21)# | 17(3) s | β+ | 123Ba | 11/2−# | ||||||||||||
| 124La | 57 | 67 | 123.924574(61) | 29.21(17) s | β+ | 124Ba | (7−, 8−) | ||||||||||||
| 124mLa[n 10] | 100(100)# keV | 21(4) s | β+ | 124Ba | 2−# | ||||||||||||||
| 125La | 57 | 68 | 124.920816(28) | 64.8(12) s | β+ | 125Ba | 11/2−# | ||||||||||||
| 125mLa | 107.00(10) keV | 390(40) ms | IT | 125La | (3/2+) | ||||||||||||||
| 126La | 57 | 69 | 125.919513(97) | 54(2) s | β+ | 126Ba | 5−# | ||||||||||||
| 126mLa[n 10] | 210(410) keV | 20(20) s | β+ | 126Ba | 1−# | ||||||||||||||
| 127La | 57 | 70 | 126.916375(28) | 5.1(1) min | β+ | 127Ba | (11/2−) | ||||||||||||
| 127mLa | 14.2(4) keV | 3.7(4) min | β+ | 127Ba | (3/2+) | ||||||||||||||
| 128La | 57 | 71 | 127.915592(58) | 5.18(14) min | β+ | 128Ba | (5+) | ||||||||||||
| 128mLa[n 10] | 100(100)# keV | <1.4 min | β+ | 128Ba | (1+, 2−) | ||||||||||||||
| 129La | 57 | 72 | 128.912696(23) | 11.6(2) min | β+ | 129Ba | (3/2+) | ||||||||||||
| 129mLa | 172.33(20) keV | 560(50) ms | IT | 129La | (11/2−) | ||||||||||||||
| 130La | 57 | 73 | 129.912369(28) | 8.7(1) min | β+ | 130Ba | 3(+) | ||||||||||||
| 130mLa | 214.0(5) keV | 742(28) ns | IT | 130La | (5+) | ||||||||||||||
| 131La | 57 | 74 | 130.910070(30) | 59(2) min | β+ | 131Ba | 3/2+ | ||||||||||||
| 131mLa | 304.52(24) keV | 170(10) μs | IT | 131La | 11/2− | ||||||||||||||
| 132La | 57 | 75 | 131.910119(39) | 4.59(4) h | β+ | 132Ba | 2− | ||||||||||||
| 132mLa | 188.20(11) keV | 24.3(5) min | IT (76%) | 132La | 6− | ||||||||||||||
| β+ (24%) | 132Ba | ||||||||||||||||||
| 133La | 57 | 76 | 132.908218(30) | 3.912(8) h | β+ | 133Ba | 5/2+ | ||||||||||||
| 134La | 57 | 77 | 133.908514(21) | 6.45(16) min | β+ | 134Ba | 1+ | ||||||||||||
| 134mLa | 440(100)# keV | 29(4) μs | IT | 134La | (6−) | ||||||||||||||
| 135La | 57 | 78 | 134.906984(10) | 18.91(2) h | β+ | 135Ba | 5/2+ | ||||||||||||
| 136La | 57 | 79 | 135.907635(57) | 9.87(3) min | β+ | 136Ba | 1+ | ||||||||||||
| 136m1La | 259.5(3) keV | 114(5) ms | IT | 136La | (7−) | ||||||||||||||
| 136m2La | 2520.6(4) keV | 187(27) ns | IT | 136La | (14+) | ||||||||||||||
| 137La | 57 | 80 | 136.9064504(18) | 6(2)×104 y | EC | 137Ba | 7/2+ | ||||||||||||
| 137mLa | 1869.50(21) keV | 342(25) ns | IT | 137La | 19/2− | ||||||||||||||
| 138La[n 11] | 57 | 81 | 137.90712404(45) | 1.03(1)×1011 y | β+ (65.5%) | 138Ba | 5+ | 8.881(71)×10−4 | |||||||||||
| β− (34.5%) | 138Ce | ||||||||||||||||||
| 138m1La | 72.57(3) keV | 116(5) ns | IT | 138La | (3)+ | ||||||||||||||
| 138m2La | 738.80(20) keV | 2.0(3) μs | IT | 138La | 7− | ||||||||||||||
| 139La[n 12] | 57 | 82 | 138.90636293(65) | Stable | 7/2+ | 0.9991119(71) | |||||||||||||
| 139mLa | 1800.4(4) keV | 315(35) ns | IT | 139La | (17/2+) | ||||||||||||||
| 140La[n 12] | 57 | 83 | 139.90948729(65) | 40.289(4) h | β− | 140Ce | 3− | ||||||||||||
| 141La | 57 | 84 | 140.9109712(44) | 3.92(3) h | β− | 141Ce | (7/2+) | ||||||||||||
| 142La | 57 | 85 | 141.9140908(67) | 91.1(5) min | β− | 142Ce | 2− | ||||||||||||
| 142mLa | 145.82(8) keV | 0.87(17) μs | IT | 142La | (4)− | ||||||||||||||
| 143La | 57 | 86 | 142.9160795(79) | 14.2(1) min | β− | 143Ce | (7/2)+ | ||||||||||||
| 144La | 57 | 87 | 143.919646(14) | 44.0(7) s | β− | 144Ce | (3−) | ||||||||||||
| 145La | 57 | 88 | 144.921808(13) | 24.8(20) s | β− | 145Ce | (5/2+) | ||||||||||||
| 146La | 57 | 89 | 145.9256880(18) | 9.9(1) s | β− | 146Ce | (5−) | ||||||||||||
| 146mLa | 141.5(24) keV | 6.08(22) s | β− | 146Ce | (1−, 2−) | ||||||||||||||
| 147La | 57 | 90 | 146.928418(12) | 4.026(20) s | β− (99.96%) | 147Ce | (5/2+) | ||||||||||||
| β−, n (0.041%) | 146Ce | ||||||||||||||||||
| 148La | 57 | 91 | 147.932679(21) | 1.414(25) s | β− (99.82%) | 148Ce | (2−) | ||||||||||||
| β−, n (0.18%) | 147Ce | ||||||||||||||||||
| 149La | 57 | 92 | 148.93535(21) | 1.071(22) s | β− (98.57%) | 149Ce | (3/2−) | ||||||||||||
| β−, n (1.43%) | 148Ce | ||||||||||||||||||
| 150La | 57 | 93 | 149.9395475(27) | 504(15) ms | β− (97.3%) | 150Ce | (3+) | ||||||||||||
| β−, n (2.7%) | 149Ce | ||||||||||||||||||
| 151La | 57 | 94 | 150.94277(47) | 465(24) ms | β− | 151Ce | 1/2+# | ||||||||||||
| 152La | 57 | 95 | 151.94709(32)# | 287(16) ms | β− | 152Ce | 2−# | ||||||||||||
| 153La | 57 | 96 | 152.95055(32)# | 245(18) ms | β− | 153Ce | 1/2+# | ||||||||||||
| 154La | 57 | 97 | 153.95542(32)# | 161(15) ms | β− | 154Ce | 2−# | ||||||||||||
| 155La | 57 | 98 | 154.95928(43)# | 101(28) ms | β− | 155Ce | 1/2+# | ||||||||||||
| 156La | 57 | 99 | 155.96452(43)# | 84(78) ms | β− | 156Ce | 4+# | ||||||||||||
| 157La | 57 | 100 | 156.96879(32)# | 30# ms [>550 ns] |
1/2+# | ||||||||||||||
| This table header & footer: | |||||||||||||||||||
- ^ mLa – Excited nuclear isomer.
- ^ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
- ^ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
- ^ Bold half-life – nearly stable, half-life longer than age of universe.
- ^ a b c # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
- ^
Modes of decay:
EC: Electron capture IT: Isomeric transition n: Neutron emission p: Proton emission - ^ Bold italics symbol as daughter – Daughter product is nearly stable.
- ^ Bold symbol as daughter – Daughter product is stable.
- ^ ( ) spin value – Indicates spin with weak assignment arguments.
- ^ a b c Order of ground state and isomer is uncertain.
- ^ Primordial radionuclide
- ^ a b Fission product
References
edit- ^ a b c d e Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
- ^ "Standard Atomic Weights: Lanthanum". CIAAW. 2005.
- ^ Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
- ^ Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3): 030003. doi:10.1088/1674-1137/abddaf.
- ^ a b c d Zhang, Wei; Cederwall, Bo; Aktas, Özge; Liu, Xiaoyu; Ertoprak, Aysegül; Nyberg, Ayse; Auranen, Kalle; Alayed, Betool; Badran, Hussam; Boston, Helen; Doncel, Maria; Forsberg, Ulrika; Grahn, Tuomas; Greenlees, Paul T.; Guo, Song; Heery, Jacob; Hilton, Joshua; Jenkins, David; Julin, Rauno; Juutinen, Sakari; Luoma, Minna; Neuvonen, Olavi; Ojala, Joonas; Page, Robert D.; Pakarinen, Janne; Partanen, Jari; Paul, Edward S.; Petrache, Costel; Rahkila, Panu; Ruotsalainen, Panu; Sandzelius, Mikael; Sarén, Jan; Szwec, Stuart; Tann, Holly; Uusitalo, Juha; Wadsworth, Robert (14 November 2022). "Observation of the proton emitter 116
57La
59" (PDF). Communications Physics. 5 (1): 1–8. doi:10.1038/s42005-022-01069-w. ISSN 2399-3650. S2CID 253512231. - ^ a b Jodidar, P.M.; Petrache, C.M.; Lv, B.F.; Lawrie, E.A.; Astier, A.; Guo, S.; Zheng, K.K.; Auranen, K.; Briscoe, A.D.; Grahn, T.; Greenlees, P.T.; Illana, A.; Joukainen, H.; Julin, R.; Louko, J.; Luoma, M.; Jutila, H.; Ojala, J.; Pakarinen, J.; Plaza, A.M.; Rahkila, P.; Ruotsalainen, P.; Sarén, J.; Tolosa-Delgado, A.; Uusitalo, J.; Zimba, G.; Kuti, I.; Krakó, A.; Andreoiu, C.; Joss, D.T.; Page, R.D.; Cederlöf, E.A.; Ertoprak, A. (August 2024). "First observation of excited states in 120La and its impact on the shape evolution in the A ≈ 120 mass region" (PDF). Physics Letters B. 855: 138806. doi:10.1016/j.physletb.2024.138806.
- Isotope masses from:
- Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
- Isotopic compositions and standard atomic masses from:
- de Laeter, John Robert; Böhlke, John Karl; De Bièvre, Paul; Hidaka, Hiroshi; Peiser, H. Steffen; Rosman, Kevin J. R.; Taylor, Philip D. P. (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.
- Wieser, Michael E. (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051.
- "News & Notices: Standard Atomic Weights Revised". International Union of Pure and Applied Chemistry. 19 October 2005.
- Half-life, spin, and isomer data selected from the following sources.
- Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
- National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory.
- Holden, Norman E. (2004). "11. Table of the Isotopes". In Lide, David R. (ed.). CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. ISBN 978-0-8493-0485-9.