Lanthanum-139

Isotopes of lanthanum

Isotopes of lanthanum

Nuclides with atomic number of 57 but with different mass numbers

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. Lighter isotopes mostly decay to isotopes of barium and heavy ones mostly decay to isotopes of cerium. 138La can decay to both.

Quick Facts Main isotopes, Decay ...
Stable Z/N chart of La and Ba

The isotopes of lanthanum range in atomic weight from 115.96 u (116La) to 154.96 u (155La).

List of isotopes

More information Nuclide, Z ...
  1. [n 1]
    mLa – Excited nuclear isomer.
  2. [n 2]
    ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
  3. [n 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. [n 4]
    Bold half-life – nearly stable, half-life longer than age of universe.
  5. [n 5]
    # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  6. [n 6]
    Modes of decay:
    EC:Electron capture
    IT:Isomeric transition
    n:Neutron emission
    p:Proton emission
  7. [n 7]
    Bold italics symbol as daughter – Daughter product is nearly stable.
  8. [n 8]
    Bold symbol as daughter – Daughter product is stable.
  9. [n 9]
    ( ) spin value – Indicates spin with weak assignment arguments.
  10. [N 10]
    Primordial radionuclide
  11. [N 11]
    Fission product

References

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  2. [2]
    "Standard Atomic Weights: Lanthanum". CIAAW. 2005.
  3. [3]
    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.
  4. [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
    57    La
    59    "     (PDF). Communications Physics. 5 (1): 1–8. doi:10.1038/s42005-022-01069-w. ISSN 2399-3650. S2CID 253512231.
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