Menu
Home Explore People Places Arts History Plants & Animals Science Life & Culture Technology
On this page
Isotopes of calcium
Isotope with 20 protons per atom

Calcium (20Ca) has 26 known isotopes, ranging from 35Ca to 60Ca. There are five stable isotopes (40Ca, 42Ca, 43Ca, 44Ca and 46Ca), plus one isotope (48Ca) with such a long half-life that it is for all practical purposes stable. The most abundant isotope, 40Ca, as well as the rare 46Ca, are theoretically unstable on energetic grounds, but their decay has not been observed. Calcium also has a cosmogenic isotope, 41Ca, with half-life 99,400 years. Unlike cosmogenic isotopes that are produced in the air, 41Ca is produced by neutron activation of 40Ca. Most of its production is in the upper metre of the soil column, where the cosmogenic neutron flux is still strong enough. 41Ca has received much attention in stellar studies because it decays to 41K, a critical indicator of solar system anomalies. The most stable artificial isotopes are 45Ca with half-life 163 days and 47Ca with half-life 4.5 days. All other calcium isotopes have half-lives of minutes or less.

Stable 40Ca comprises about 97% of natural calcium and is mainly created by nucleosynthesis in large stars. Similarly to 40Ar, however, some atoms of 40Ca are radiogenic, created through the radioactive decay of 40K. While K–Ar dating has been used extensively in the geological sciences, the prevalence of 40Ca in nature initially impeded the proliferation of K-Ca dating in early studies, with only a handful of studies in the 20th century. Modern techniques using increasingly precise Thermal-Ionization (TIMS) and Collision-Cell Multi-Collector Inductively-coupled plasma mass spectrometry (CC-MC-ICP-MS) techniques, however, have been used for successful K–Ca age dating, as well as determining K losses from the lower continental crust and for source-tracing calcium contributions from various geologic reservoirs similar to Rb-Sr.

Stable isotope variations of calcium (most typically 44Ca/40Ca or 44Ca/42Ca, denoted as 'δ44Ca' and 'δ44/42Ca' in delta notation) are also widely used across the natural sciences for a number of applications, ranging from early determination of osteoporosis to quantifying volcanic eruption timescales. Other applications include: quantifying carbon sequestration efficiency in CO2 injection sites and understanding ocean acidification, exploring both ubiquitous and rare magmatic processes, such as formation of granites and carbonatites, tracing modern and ancient trophic webs including in dinosaurs, assessing weaning practices in ancient humans, and a plethora of other emerging applications.

List of isotopes

NuclideZNIsotopic mass (Da)1718Half-life1920Decaymode2122Daughterisotope23Spin andparity242526Natural abundance (mole fraction)
Normal proportion27Range of variation
35Ca201535.00557(22)#25.7(2) msβ+, p (95.8%)34Ar1/2+#
β+, 2p (4.2%)33Cl
β+ (rare)35K
36Ca201635.993074(43)100.9(13) msβ+, p (51.2%)35Ar0+
β+ (48.8%)36K
37Ca201736.98589785(68)181.0(9) msβ+, p (76.8%)36Ar3/2+
β+ (23.2%)37K
38Ca201837.97631922(21)443.70(25) msβ+38K0+
39Ca201938.97071081(64)860.3(8) msβ+39K3/2+
40Ca28202039.962590850(22)Observationally stable290+0.9694(16)0.96933–0.96947
41Ca202140.96227791(15)9.94(15)×104 yEC41K7/2−Trace30
42Ca202241.95861778(16)Stable0+0.00647(23)0.00646–0.00648
43Ca202342.95876638(24)Stable7/2−0.00135(10)0.00135–0.00135
44Ca202443.95548149(35)Stable0+0.0209(11)0.02082–0.02092
45Ca202544.95618627(39)162.61(9) dβ−45Sc7/2−
46Ca202645.9536877(24)Observationally stable310+4×10−54×10−5–4×10−5
47Ca202746.9545411(24)4.536(3) dβ−47Sc7/2−
48Ca3233202847.952522654(18)5.6(10)×1019 yβ−β−343548Ti0+0.00187(21)0.00186–0.00188
49Ca202948.95566263(19)8.718(6) minβ−49Sc3/2−
50Ca203049.9574992(17)13.45(5) sβ−50Sc0+
51Ca203150.96099566(56)10.0(8) sβ−51Sc3/2−
β−, n?50Sc
52Ca203251.96321365(72)4.6(3) sβ− (>98%)52Sc0+
β−, n (<2%)51Sc
53Ca203352.968451(47)461(90) msβ− (60%)53Sc1/2−#
β−, n (40%)52Sc
54Ca203453.972989(52)90(6) msβ−54Sc0+
β−, n?53Sc
β−, 2n?52Sc
55Ca203554.97998(17)22(2) msβ−55Sc5/2−#
β−, n?54Sc
β−, 2n?53Sc
56Ca203655.98550(27)11(2) msβ−56Sc0+
β−, n?55Sc
β−, 2n?54Sc
57Ca203756.99296(43)#8# ms [>620 ns]β−?57Sc5/2−#
β−, n?56Sc
β−, 2n?55Sc
58Ca203857.99836(54)#4# ms [>620 ns]β−?58Sc0+
β−, n?57Sc
β−, 2n?56Sc
59Ca203959.00624(64)#5# ms [>400 ns]β−?59Sc5/2−#
β−, n?58Sc
β−, 2n?57Sc
60Ca204060.01181(75)#2# ms [>400 ns]β−?60Sc0+
β−, n?59Sc
β−, 2n?58Sc
This table header & footer:
  • view

Calcium-48

Main article: Calcium-48

Calcium-48 is a doubly magic nucleus with 28 neutrons; unusually neutron-rich for a light primordial nucleus. It decays via double beta decay with an extremely long half-life of about 6.4×1019 years, though single beta decay is also theoretically possible.36 This decay can analyzed with the sd nuclear shell model, and it is more energetic (4.27 MeV) than any other double beta decay.37 It can also be used as a precursor for neutron-rich and superheavy nuclei.3839

Calcium-60

Calcium-60 is the heaviest known isotope as of 2020[update].40 First observed in 2018 at Riken alongside 59Ca and seven isotopes of other elements,41 its existence suggests that there are additional even-N isotopes of calcium up to at least 70Ca, while 59Ca is probably the last bound isotope with odd N.42 Earlier predictions had estimated the neutron drip line to occur at 60Ca, with 59Ca unbound.43

In the neutron-rich region, N = 40 becomes a magic number, so 60Ca was considered early on to be a possibly doubly magic nucleus, as is observed for the 68Ni isotone.4445 However, subsequent spectroscopic measurements of the nearby nuclides 56Ca, 58Ca, and 62Ti instead predict that it should lie on the island of inversion known to exist around 64Cr.4647

Further reading

References

  1. Audi, G.; Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S. (2017). "The NUBASE2016 evaluation of nuclear properties" (PDF). Chinese Physics C. 41 (3): 030001. Bibcode:2017ChPhC..41c0001A. doi:10.1088/1674-1137/41/3/030001. https://www-nds.iaea.org/amdc/ame2016/NUBASE2016.pdf ↩

  2. Marshall, B. D.; DePaolo, D. J. (1982-12-01). "Precise age determinations and petrogenetic studies using the KCa method". Geochimica et Cosmochimica Acta. 46 (12): 2537–2545. doi:10.1016/0016-7037(82)90376-3. ISSN 0016-7037. https://www.sciencedirect.com/science/article/abs/pii/0016703782903763 ↩

  3. admin. "K-Ca dating and Ca isotope composition of the oldest Solar System lava, Erg Chech 002 | Geochemical Perspectives Letters". Retrieved 2024-10-16. https://www.geochemicalperspectivesletters.org/article2302/ ↩

  4. admin. "Radiogenic Ca isotopes confirm post-formation K depletion of lower crust | Geochemical Perspectives Letters". Retrieved 2024-10-16. https://www.geochemicalperspectivesletters.org/article1904/ ↩

  5. Antonelli, Michael A.; DePaolo, Donald J.; Christensen, John N.; Wotzlaw, Jörn-Frederik; Pester, Nicholas J.; Bachmann, Olivier (2021-09-16). "Radiogenic 40 Ca in Seawater: Implications for Modern and Ancient Ca Cycles". ACS Earth and Space Chemistry. 5 (9): 2481–2492. doi:10.1021/acsearthspacechem.1c00179. ISSN 2472-3452. https://pubs.acs.org/doi/10.1021/acsearthspacechem.1c00179 ↩

  6. Davenport, Jesse; Caro, Guillaume; France-Lanord, Christian (2022-12-01). "Decoupling of physical and chemical erosion in the Himalayas revealed by radiogenic Ca isotopes". Geochimica et Cosmochimica Acta. 338: 199–219. doi:10.1016/j.gca.2022.10.031. ISSN 0016-7037. https://www.sciencedirect.com/science/article/abs/pii/S0016703722005804 ↩

  7. Eisenhauer, A.; Müller, M.; Heuser, A.; Kolevica, A.; Glüer, C. -C.; Both, M.; Laue, C.; Hehn, U. v.; Kloth, S.; Shroff, R.; Schrezenmeir, J. (2019-06-01). "Calcium isotope ratios in blood and urine: A new biomarker for the diagnosis of osteoporosis". Bone Reports. 10: 100200. doi:10.1016/j.bonr.2019.100200. ISSN 2352-1872. PMC 6453776. PMID 30997369. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6453776 ↩

  8. Antonelli, Michael A.; Mittal, Tushar; McCarthy, Anders; Tripoli, Barbara; Watkins, James M.; DePaolo, Donald J. (2019-10-08). "Ca isotopes record rapid crystal growth in volcanic and subvolcanic systems". Proceedings of the National Academy of Sciences. 116 (41): 20315–20321. doi:10.1073/pnas.1908921116. ISSN 0027-8424. PMC 6789932. PMID 31548431. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6789932 ↩

  9. Pogge von Strandmann, Philip A. E.; Burton, Kevin W.; Snæbjörnsdóttir, Sandra O.; Sigfússon, Bergur; Aradóttir, Edda S.; Gunnarsson, Ingvi; Alfredsson, Helgi A.; Mesfin, Kiflom G.; Oelkers, Eric H.; Gislason, Sigurður R. (2019-04-30). "Rapid CO2 mineralisation into calcite at the CarbFix storage site quantified using calcium isotopes". Nature Communications. 10 (1): 1983. doi:10.1038/s41467-019-10003-8. ISSN 2041-1723. PMC 6491611. PMID 31040283. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6491611 ↩

  10. Fantle, Matthew S.; Ridgwell, Andy (2020-08-05). "Towards an understanding of the Ca isotopic signal related to ocean acidification and alkalinity overshoots in the rock record". Chemical Geology. 547: 119672. doi:10.1016/j.chemgeo.2020.119672. ISSN 0009-2541. https://www.sciencedirect.com/science/article/abs/pii/S0009254120302114 ↩

  11. Antonelli, Michael A.; Yakymchuk, Chris; Schauble, Edwin A.; Foden, John; Janoušek, Vojtěch; Moyen, Jean-François; Hoffmann, Jan; Moynier, Frédéric; Bachmann, Olivier (2023-04-15). "Granite petrogenesis and the δ44Ca of continental crust". Earth and Planetary Science Letters. 608: 118080. doi:10.1016/j.epsl.2023.118080. hdl:20.500.11850/603069. ISSN 0012-821X. https://www.sciencedirect.com/science/article/pii/S0012821X23000936 ↩

  12. admin. "Calcium isotope fractionation during melt immiscibility and carbonatite petrogenesis | Geochemical Perspectives Letters". Retrieved 2024-10-16. https://www.geochemicalperspectivesletters.org/article2338/ ↩

  13. Skulan, Joseph; DePaolo, Donald J.; Owens, Thomas L. (1997-06-01). "Biological control of calcium isotopic abundances in the global calcium cycle". Geochimica et Cosmochimica Acta. 61 (12): 2505–2510. doi:10.1016/S0016-7037(97)00047-1. ISSN 0016-7037. https://www.sciencedirect.com/science/article/abs/pii/S0016703797000471 ↩

  14. admin. "Calcium stable isotopes place Devonian conodonts as first level consumers | Geochemical Perspectives Letters". Retrieved 2024-10-16. https://www.geochemicalperspectivesletters.org/article1912/ ↩

  15. Hassler, A.; Martin, J. E.; Amiot, R.; Tacail, T.; Godet, F. Arnaud; Allain, R.; Balter, V. (2018-04-11). "Calcium isotopes offer clues on resource partitioning among Cretaceous predatory dinosaurs". Proceedings of the Royal Society B: Biological Sciences. 285 (1876): 20180197. doi:10.1098/rspb.2018.0197. ISSN 0962-8452. PMC 5904318. PMID 29643213. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5904318 ↩

  16. Tacail, Théo; Thivichon-Prince, Béatrice; Martin, Jeremy E.; Charles, Cyril; Viriot, Laurent; Balter, Vincent (2017-06-13). "Assessing human weaning practices with calcium isotopes in tooth enamel". Proceedings of the National Academy of Sciences. 114 (24): 6268–6273. doi:10.1073/pnas.1704412114. ISSN 0027-8424. PMC 5474782. PMID 28559355. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5474782 ↩

  17. 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. /wiki/Doi_(identifier) ↩

  18. ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits. ↩

  19. 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. https://www-nds.iaea.org/amdc/ame2020/NUBASE2020.pdf ↩

  20. Bold half-life – nearly stable, half-life longer than age of universe. /wiki/Age_of_universe ↩

  21. 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. https://www-nds.iaea.org/amdc/ame2020/NUBASE2020.pdf ↩

  22. Modes of decay: EC:Electron capturen:Neutron emissionp:Proton emission /wiki/Electron_capture ↩

  23. Bold symbol as daughter – Daughter product is stable. ↩

  24. 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. https://www-nds.iaea.org/amdc/ame2020/NUBASE2020.pdf ↩

  25. ( ) spin value – Indicates spin with weak assignment arguments. ↩

  26. # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN). ↩

  27. 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. https://www-nds.iaea.org/amdc/ame2020/NUBASE2020.pdf ↩

  28. Heaviest observationally stable nuclide with equal numbers of protons and neutrons ↩

  29. Believed to undergo double electron capture to 40Ar with a half-life no less than 9.9×1021 y /wiki/Double_electron_capture ↩

  30. Cosmogenic nuclide /wiki/Cosmogenic_nuclide ↩

  31. Believed to undergo β−β− decay to 46Ti ↩

  32. Primordial radionuclide /wiki/Primordial_nuclide ↩

  33. Believed to be capable of undergoing triple beta decay with very long partial half-life /wiki/Double_beta_decay ↩

  34. Lightest nuclide known to undergo double beta decay /wiki/Double_beta_decay ↩

  35. Theorized to also undergo β− decay to 48Sc with a partial half-life exceeding 1.1+0.8−0.6×1021 years[21] /wiki/Partial_half-life ↩

  36. Arnold, R.; et al. (NEMO-3 Collaboration) (2016). "Measurement of the double-beta decay half-life and search for the neutrinoless double-beta decay of 48Ca with the NEMO-3 detector". Physical Review D. 93 (11): 112008. arXiv:1604.01710. Bibcode:2016PhRvD..93k2008A. doi:10.1103/PhysRevD.93.112008. /wiki/NEMO-3_Collaboration ↩

  37. Balysh, A.; et al. (1996). "Double Beta Decay of 48Ca". Physical Review Letters. 77 (26): 5186–5189. arXiv:nucl-ex/9608001. Bibcode:1996PhRvL..77.5186B. doi:10.1103/PhysRevLett.77.5186. PMID 10062737. /wiki/ArXiv_(identifier) ↩

  38. Notani, M.; et al. (2002). "New neutron-rich isotopes, 34Ne, 37Na and 43Si, produced by fragmentation of a 64A MeV 48Ca beam". Physics Letters B. 542 (1–2): 49–54. Bibcode:2002PhLB..542...49N. doi:10.1016/S0370-2693(02)02337-7. /wiki/Bibcode_(identifier) ↩

  39. Oganessian, Yu. Ts.; et al. (October 2006). "Synthesis of the isotopes of elements 118 and 116 in the 249Cf and 245Cm + 48Ca fusion reactions". Physical Review C. 74 (4): 044602. Bibcode:2006PhRvC..74d4602O. doi:10.1103/PhysRevC.74.044602. https://doi.org/10.1103%2FPhysRevC.74.044602 ↩

  40. 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. https://www-nds.iaea.org/amdc/ame2020/NUBASE2020.pdf ↩

  41. Tarasov, O. B.; Ahn, D. S.; Bazin, D.; et al. (11 July 2018). "Discovery of 60Ca and Implications For the Stability of 70Ca". Physical Review Letters. 121 (2): 022501. doi:10.1103/PhysRevLett.121.022501. PMID 30085743. https://doi.org/10.1103%2FPhysRevLett.121.022501 ↩

  42. Neufcourt, Léo; Cao, Yuchen; Nazarewicz, Witold; et al. (14 February 2019). "Neutron Drip Line in the Ca Region from Bayesian Model Averaging". Physical Review Letters. 122 (6): 062502. arXiv:1901.07632. doi:10.1103/PhysRevLett.122.062502. PMID 30822058. /wiki/ArXiv_(identifier) ↩

  43. Tarasov, O. B.; Ahn, D. S.; Bazin, D.; et al. (11 July 2018). "Discovery of 60Ca and Implications For the Stability of 70Ca". Physical Review Letters. 121 (2): 022501. doi:10.1103/PhysRevLett.121.022501. PMID 30085743. https://doi.org/10.1103%2FPhysRevLett.121.022501 ↩

  44. Gade, A.; Janssens, R. V. F.; Weisshaar, D.; et al. (21 March 2014). "Nuclear Structure Towards N = 40 60Ca: In-Beam γ -Ray Spectroscopy of 58, 60Ti". Physical Review Letters. 112 (11): 112503. arXiv:1402.5944. doi:10.1103/PhysRevLett.112.112503. PMID 24702356. /wiki/ArXiv_(identifier) ↩

  45. Cortés, M.L.; Rodriguez, W.; Doornenbal, P.; et al. (January 2020). "Shell evolution of N = 40 isotones towards 60Ca: First spectroscopy of 62Ti". Physics Letters B. 800: 135071. arXiv:1912.07887. doi:10.1016/j.physletb.2019.135071. https://doi.org/10.1016%2Fj.physletb.2019.135071 ↩

  46. Cortés, M.L.; Rodriguez, W.; Doornenbal, P.; et al. (January 2020). "Shell evolution of N = 40 isotones towards 60Ca: First spectroscopy of 62Ti". Physics Letters B. 800: 135071. arXiv:1912.07887. doi:10.1016/j.physletb.2019.135071. https://doi.org/10.1016%2Fj.physletb.2019.135071 ↩

  47. Chen, S.; Browne, F.; Doornenbal, P.; et al. (August 2023). "Level structures of 56, 58Ca cast doubt on a doubly magic 60Ca". Physics Letters B. 843: 138025. arXiv:2307.07077. doi:10.1016/j.physletb.2023.138025. https://doi.org/10.1016%2Fj.physletb.2023.138025 ↩