Isotopes of lanthanum

Nuclides with atomic number of 57 but with different mass numbers

Isotopes of lanthanum (57La) | Main isotopes[1] | Decay

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| abun­dance | half-life (t1/2) | mode | pro­duct
137La  | synth | 6×104 y | ε | 137Ba
138La  | 0.089% | 1.05×1011 y | ε | 138Ba
β− | 138Ce
139La  | 99.911% | stable
Standard atomic weight Ar°(La)

* 138.90547±0.00007[2]
* 138.91±0.01 (abridged)[3]

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Stable Z/N chart of La and Ba

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 1.02×1011 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.

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)
[n 2][n 3] | Half-life
[n 4][n 5] | Decay
mode
[n 6] | Daughter
isotope
[n 7][n 8] | Spin and
parity
[n 9][n 5] | Natural abundance (mole fraction) | Note

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Excitation energy[n 5] | Normal proportion  | Range of variation
116La[4] | 57  | 59  |  | 50(22) ms  | p (~60%)  | 115Ba  |  |  |
β+ (~40%)  | 116Ba
117La  | 57  | 60  | 116.95007(43)#  | 23.5(26) ms  | β+ | 117Ba  | (3/2+, 3/2−)  |  |
p  | 116Ba
117mLa  | 151(12) keV  | 10(5) ms  |  |  | (9/2+)  |  |
118La  | 57  | 61  | 117.94673(32)#  | 200# ms  | β+ | 118Ba  |  |  |
119La  | 57  | 62  | 118.94099(43)#  | 1# s  | β+ | 119Ba  | 11/2−#  |  |
120La  | 57  | 63  | 119.93807(54)#  | 2.8(2) s  | β+ | 120Ba  |  |  |
β+, p  | 119Cs
121La  | 57  | 64  | 120.93301(54)#  | 5.3(2) s  | β+ | 121Ba  | 11/2−#  |  |
β+, p  | 120Cs
122La  | 57  | 65  | 121.93071(32)#  | 8.6(5) s  | β+ | 122Ba  |  |  |
β+, p  | 121Cs
123La  | 57  | 66  | 122.92624(21)#  | 17(3) s  | β+ | 123Ba  | 11/2−#  |  |
124La  | 57  | 67  | 123.92457(6)  | 29.21(17) s  | β+ | 124Ba  | (7−, 8−)  |  |
124mLa  | 100(100)# keV  | 21(4) s  |  |  | low(+#)  |  |
125La  | 57  | 68  | 124.920816(28)  | 64.8(12) s  | β+ | 125Ba  | (11/2−)  |  |
125mLa  | 107.0(10) keV  | 390(40) ms  |  |  | (3/2+)  |  |
126La  | 57  | 69  | 125.91951(10)  | 54(2) s  | β+ | 126Ba  | (5)(+#)  |  |
126mLa  | 210(410) keV  | 20(20) s  |  |  | (0−, 1−, 2−)  |  |
127La  | 57  | 70  | 126.916375(28)  | 5.1(1) min  | β+ | 127Ba  | (11/2−)  |  |
127mLa  | 14.8(12) keV  | 3.7(4) min  | β+ | 127Ba  | (3/2+)  |  |
IT | 127La
128La  | 57  | 71  | 127.91559(6)  | 5.18(14) min  | β+ | 128Ba  | (5+)  |  |
128mLa  | 100(100)# keV  | <1.4 min  | IT  | 128La  | (1+, 2−)  |  |
129La  | 57  | 72  | 128.912693(22)  | 11.6(2) min  | β+ | 129Ba  | 3/2+  |  |
129mLa  | 172.1(4) keV  | 560(50) ms  | IT  | 129La  | 11/2−  |  |
130La  | 57  | 73  | 129.912369(28)  | 8.7(1) min  | β+ | 130Ba | 3(+)  |  |
131La  | 57  | 74  | 130.91007(3)  | 59(2) min  | β+ | 131Ba  | 3/2+  |  |
131mLa  | 304.52(24) keV  | 170(10) μs  |  |  | 11/2−  |  |
132La  | 57  | 75  | 131.91010(4)  | 4.8(2) h  | β+ | 132Ba | 2−  |  |
132mLa  | 188.18(11) keV  | 24.3(5) min  | IT (76%)  | 132La  | 6−  |  |
β+ (24%)  | 132Ba
133La  | 57  | 76  | 132.90822(3)  | 3.912(8) h  | β+ | 133Ba  | 5/2+  |  |
134La  | 57  | 77  | 133.908514(21)  | 6.45(16) min  | β+ | 134Ba | 1+  |  |
135La  | 57  | 78  | 134.906977(11)  | 19.5(2) h  | β+ | 135Ba | 5/2+  |  |
136La  | 57  | 79  | 135.90764(6)  | 9.87(3) min  | β+ | 136Ba | 1+  |  |
136mLa  | 255(9) keV  | 114(3) ms  | IT  | 136La  | (8)(−#)  |  |
137La  | 57  | 80  | 136.906494(14)  | 6(2)×104 y  | EC | 137Ba | 7/2+  |  |  | extinct
138La[n 10] | 57  | 81  | 137.907112(4)  | 1.02(1)×1011 y | β+ (66.4%)  | 138Ba | 5+  | 9.0(1)×10−4 |
β− (33.6%)  | 138Ce
138mLa  | 72.57(3) keV  | 116(5) ns  |  |  | (3)+  |  |
139La[n 11] | 57  | 82  | 138.9063533(26)  | Stable | 7/2+  | 0.99910(1)  |
140La[n 11] | 57  | 83  | 139.9094776(26)  | 1.6781(3) d  | β− | 140Ce | 3−  |  |
141La  | 57  | 84  | 140.910962(5)  | 3.92(3) h  | β− | 141Ce  | (7/2+)  |  |
142La  | 57  | 85  | 141.914079(6)  | 91.1(5) min  | β− | 142Ce | 2−  |  |
143La  | 57  | 86  | 142.916063(17)  | 14.2(1) min  | β− | 143Ce  | (7/2)+  |  |
144La  | 57  | 87  | 143.91960(5)  | 40.8(4) s  | β− | 144Ce  | (3−)  |  |
145La  | 57  | 88  | 144.92165(10)  | 24.8(20) s  | β− | 145Ce  | (5/2+)  |  |
146La  | 57  | 89  | 145.92579(8)  | 6.27(10) s  | β− (99.99%)  | 146Ce  | 2−  |  |
β−, n (.007%)  | 145Ce
146mLa  | 130(130) keV  | 10.0(1) s  | β− | 146Ce  | (6−)  |  |
147La  | 57  | 90  | 146.92824(5)  | 4.015(8) s  | β− (99.96%)  | 147Ce  | (5/2+)  |  |
β−, n (.04%)  | 146Ce
148La  | 57  | 91  | 147.93223(6)  | 1.26(8) s  | β− (99.85%)  | 148Ce  | (2−)  |  |
β−, n (.15%)  | 147Ce
149La  | 57  | 92  | 148.93473(34)#  | 1.05(3) s  | β− (98.6%)  | 149Ce  | 5/2+#  |  |
β−, n (1.4%)  | 148Ce
150La  | 57  | 93  | 149.93877(43)#  | 510(30) ms  | β− (97.3%)  | 150Ce  | (3+)  |  |
β−, n (2.7%)  | 149Ce
151La  | 57  | 94  | 150.94172(43)#  | 300# ms [>300 ns]  | β− | 151Ce  | 5/2+#  |  |
152La  | 57  | 95  | 151.94625(43)#  | 200# ms [>300 ns]  | β− | 152Ce  |  |  |
153La  | 57  | 96  | 152.94962(64)#  | 150# ms [>300 ns]  | β− | 153Ce  | 5/2+#  |  |
154La  | 57  | 97  | 153.95450(64)#  | 100# ms  | β− | 154Ce  |  |  |
155La  | 57  | 98  | 154.95835(86)#  | 60# ms  | β− | 155Ce  | 5/2+#  |  |
This table header & footer:

* view

1. ^ mLa - 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. ^ Bold half-life - nearly stable, half-life longer than age of universe.
5. ^ a b c # - Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
6. ^ Modes of decay:  EC: | Electron capture

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IT: | Isomeric transition
n: | Neutron emission
p: | Proton emission
7. ^ Bold italics symbol as daughter - Daughter product is nearly stable.
8. ^ Bold symbol as daughter - Daughter product is stable.
9. ^ ( ) spin value - Indicates spin with weak assignment arguments.
10. ^ Primordial radionuclide
11. ^ a b Fission product

## References[edit]

1. ^ 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.
2. ^ "Standard Atomic Weights: Lanthanum". CIAAW. 2005.
3. ^ Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; et al. (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.
4. ^ 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". Communications Physics. 5 (1): 1–8. doi:10.1038/s42005-022-01069-w. ISSN 2399-3650. S2CID 253512231.11657La59&rft.volume=5&rft.issue=1&rft.pages=1-8&rft.date=2022-11-14&rft_id=https://api.semanticscholar.org/CorpusID:253512231#id-name=S2CID&rft.issn=2399-3650&rft_id=info:doi/10.1038/s42005-022-01069-w&rft.aulast=Zhang&rft.aufirst=Wei&rft.au=Cederwall,+Bo&rft.au=Aktas,+Özge&rft.au=Liu,+Xiaoyu&rft.au=Ertoprak,+Aysegül&rft.au=Nyberg,+Ayse&rft.au=Auranen,+Kalle&rft.au=Alayed,+Betool&rft.au=Badran,+Hussam&rft.au=Boston,+Helen&rft.au=Doncel,+Maria&rft.au=Forsberg,+Ulrika&rft.au=Grahn,+Tuomas&rft.au=Greenlees,+Paul+T.&rft.au=Guo,+Song&rft.au=Heery,+Jacob&rft.au=Hilton,+Joshua&rft.au=Jenkins,+David&rft.au=Julin,+Rauno&rft.au=Juutinen,+Sakari&rft.au=Luoma,+Minna&rft.au=Neuvonen,+Olavi&rft.au=Ojala,+Joonas&rft.au=Page,+Robert+D.&rft.au=Pakarinen,+Janne&rft.au=Partanen,+Jari&rft.au=Paul,+Edward+S.&rft.au=Petrache,+Costel&rft.au=Rahkila,+Panu&rft.au=Ruotsalainen,+Panu&rft.au=Sandzelius,+Mikael&rft.au=Sarén,+Jan&rft.au=Szwec,+Stuart&rft.au=Tann,+Holly&rft.au=Uusitalo,+Juha&rft.au=Wadsworth,+Robert&rft_id=https://doi.org/10.1038%2Fs42005-022-01069-w&rfr_id=info:sid/en.wikipedia.org:Isotopes+of+lanthanum" class="Z3988">

* 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.

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Isotopes of the chemical elements

| Group | 1 | 2 |  | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18

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Uue

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