Naturally occurring calcium is a cocktail of 7 different isotopes, 6 of which are stable and one is extremely long-lived (>100,000 years). At almost 97%, the isotope calcium-40 makes up the largest proportion:
| Atomic Mass ma | Quantity | Half-life | Spin | |
| Calcium Isotopic mixture | 40,078 u | 100 % | ||
| Isotope 40Ca | 39,9625909(2) u | 96,941(156) % | stable | 0+ |
| Isotope 41Ca | 40,96227792(15) u | traces | 9.94(15) × 104 a | 7/2- |
| Isotope 42Ca | 41,958618(1) u | 0,647(23) % | stable | 0+ |
| Isotope 43Ca | 42,958766(2) u | 0,135(10) % | stable | 7/2- |
| Isotope 44Ca | 43,955482(2) u | 2,086(110) % | stable | 0+ |
| Isotope 46Ca | 45,95369(2) u | 0,004(3) % | stable | 0+ |
| Isotope 48Ca | 47,952522654(19) u | 0,187(21) % | 5.3 × 1019 a | 0+ |
Due to variations in the isotopic composition of natural calcium, the mean atomic mass (standard atomic mass) may vary.
On the basis of theoretical considerations, it is assumed that the calcium isotopes 40 and 46 have extremely long half-lives of not less than 5.9 × 1021 (40approx ) and 100 × 1015 (46Ca) years a β+β+-decay to 40< /sup>Ar or 46Ti are subject; there are no corresponding confirmations yet.
The quasi-stable calcium isotope 41 is formed by neutron activation from 40Ca.
| Isotope Nuclide | E | N | Atomic Mass [Nuclear Mass] {Mass Excess} | Spin I (h/2π) | Parent |
|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 5 | 6 |
| Calcium-34 | 3420Ca | 14 | 34.01487(32) u [34.0038986 u] {13.85132 MeV} | 0+ | |
| Calcium-35 | 3520Ca | 15 | 35.00514(21) u [34.9941686 u] {4.78788 MeV} | (1/2+) | |
| Calcium-36 | 3620Ca | 16 | 35.99307(4) u [35.9820986 u] {-6.45525 MeV} | 0+ | 38Ti |
| Calcium-37 | 3720Ca | 17 | 36.9858979(7) u [36.9749265 u] {-13.13602 MeV} | (3/2+) | 38Sc |
| Calcium-38 | 3820Ca | 18 | 37.97631923(21) u [37.9653478 u] {-22.0585 MeV} | 0+ | 39Sc 39Ti |
| Calcium-39 | 3920Ca | 19 | 38.9707108(6) u [38.9597394 u] {-27.28271 MeV} | 3/2+ | 40Ti |
| Calcium-40 | 4020Ca | 20 | 39.9625909(2) u [39.9516195 u] {-34.84635 MeV} | 0+ | 40K 40Sc 41Ti |
| Calcium-41 | 4120Ca | 21 | 40.96227792(15) u [40.9513065 u] {-35.13789 MeV} | 7/2- | 41Sc |
| Calcium-42 | 4220Ca | 22 | 41.958618(1) u [41.9476466 u] {-38.54708 MeV} | 0+ | 42K 42Sc |
| Calcium-43 | 4320Ca | 23 | 42.958766(2) u [42.9477946 u] {-38.40922 MeV} | 7/2- | 43K 43Sc |
| Calcium-44 | 4420Ca | 24 | 43.955482(2) u [43.9445106 u] {-41.46825 MeV} | 0+ | 44K 44Sc |
| Calcium-45 | 4520Ca | 25 | 44.9561863(4) u [44.9452149 u] {-40.8122 MeV} | 7/2- | 45K |
| Calcium-46 | 4620Ca | 26 | 45.95369(2) u [45.9427186 u] {-43.13749 MeV} | 0+ | 46K |
| Calcium-47 | 4720Ca | 27 | 46.9545414(24) u [46.94357 u] {-42.34441 MeV} | 7/2- | 47K 48K |
| Calcium-48 | 4820Ca | 28 | 47.952522654(19) u [47.9415512 u] {-44.22486 MeV} | 0+ | 48K 49K |
| Calcium-49 | 4920Ca | 29 | 48.95562288(22) u [48.9446515 u] {-41.33702 MeV} | 3/2- | 49K 50K |
| Calcium-50 | 5020Ca | 30 | 49.9574992(17) u [49.9465278 u] {-39.58924 MeV} | 0+ | 50K 51K |
| Calcium-51 | 5120Ca | 31 | 50.9609957(6) u [50.9500243 u] {-36.33227 MeV} | 3/2(-) | 51K 52K |
| Calcium-52 | 5220Ca | 32 | 51.9632136(7) u [51.9522422 u] {-34.26631 MeV} | 0+ | 52K 53K |
| Calcium-53 | 5320Ca | 33 | 52.96845(5) u [52.9574786 u] {-29.38864 MeV} | (1/2-) | 54K |
| Calcium-54 | 5420Ca | 34 | 53.97299(5) u [53.9620186 u] {-25.15965 MeV} | 0+ | |
| Calcium-55 | 5520Ca | 35 | 54.98030(32) u [54.9693286 u] {-18.35043 MeV} | (5/2-) | |
| Calcium-56 | 5620Ca | 36 | 55.98508(43) u [55.9741086 u] {-13.89789 MeV} | 0+ | |
| Calcium-57 | 5720Ca | 37 | 56.99262(43) u [56.9816486 u] {-6.87443 MeV} | 5/2- | |
| Calcium-58 | 5820Ca | 38 | 57.99794(54) u [57.9869686 u] {-1.91888 MeV} | 0+ |
| Isotope | Radioactive Decay | Extern | |||
|---|---|---|---|---|---|
| Half-life | Decay Mode | Probability | Energy | ||
| 7 | 8 | 9 | 10 | 11 | 12 |
| Ca-34 | 35 ns | p → 33K 2p ? | ? | AL | |
| Ca-35 | 25.7(2) ms | β+ → 35K β+, p → 34Ar β+, 2p → 33Cl | < 0.1 % 95.9(14) % 4.1(6) % | 15.770 MeV 15.690 MeV 11.027 MeV | AL |
| Ca-36 | 101.2(20) ms | β+ → 36K EC, p → 35Ar | 48.8 % 51.2(10) % | 10.987 MeV 9.319 MeV | AL |
| Ca-37 | 181.1(10) ms | β+ → 37K EC, p → 36Ar | 17.9 % 82.1 % | 11.638 MeV 9.781 MeV | AL |
| Ca-38 | 443.76 (35) ms | β+ → 38K | 100 % | 6.74226(27) MeV | AL |
| Ca-39 | 860.3(10) ms | β+ → 39K | 100 % | 6.5245(6) MeV | AL |
| Ca-40 | stable | AL | |||
| Ca-41 | 9.94(15) × 104 a | EC → 41K | 100 % | 0.42165(14) MeV | AL |
| Ca-42 | stable | AL | |||
| Ca-43 | stable | AL | |||
| Ca-44 | stable | AL | |||
| Ca-45 | 162.61(9) d | β- → 45Sc | 100 % | 0.2597(7) MeV | AL |
| Ca-46 | stable | AL | |||
| Ca-47 | 4.536(3) d | β- → 47Sc | 100 % | 1.9922(12) MeV | AL |
| Ca-48 | 5.3 × 1019 a | β- → 48Sc 2β- → 48Ti | 25 % 75 % | 0.2793 MeV 4.272 MeV | AL |
| Ca-49 | 8.718(6) min | β- → 49Sc | 100 % | 5.2615(27) MeV | AL |
| Ca-50 | 13.45(5) s | β- → 50Sc | 100 % | 4.958(15) MeV | AL |
| Ca-51 | 10.0(8) s | β- → 51Sc β-, n → 50Sc | 99.9 % 0.1 % | 6.896(20) MeV 0.144(15) MeV | AL |
| Ca-52 | 4.6(3) s | β- → 52Sc β-, n → 51Sc | > 98 % < 2 % | 6.18(8) MeV 0.891(20) | AL |
| Ca-53 | 461(90) ms | β- → 53Sc β-, n → 52Sc | 60 % 40(10) % | 9.52(10) MeV 2.98(9) MeV | AL |
| Ca-54 | 107(14) ms | β- → 54Sc β-, n → 53Sc β-, 2n → 52Sc | 100 % ? ? | 8.73(28) MeV 5.67(11) MeV | AL |
| Ca-55 | 22(2) ms | β- → 55Sc β-, n → 54Sc | 100 % ? | 11.81(54) MeV 7.47(40) MeV | AL |
| Ca-56 | 11(2) ms | β- → 56Sc β-, n → 55Sc | ? ? | 10.95(71) MeV 8.19(60) MeV | AL |
| Ca-57 | 620 ns | β- → 57Sc β-, n → 56Sc β-, 2n → 55Sc | ? ? ? | 14.12(136) MeV 9.91(71) MeV | AL |
| Ca-58 | 620 ns | β- → 58Sc β-, n → 57Sc | ? ? | 12.96(64) MeV 11.01(140) MeV | AL |
Notes (related to the columns):
1 - name of the nuclide, isotope.
2 - E: isotope symbol with mass number (superscript; number of nucleons) and Atomic number (subscript; number of protons).
3 - N: number of neutrons.
4 - relative atomic mass of the Calcium isotope (isotopic mass including electrons) and the mass of the atomic nucleus in square brackets (nuclear mass, nuclide mass without electrons), each related to 12C = 12.00000 [2]. In addition, the mass excess is given in MeV.
5 - nuclear spin I, unit: h/2π.
6 - source nuclides: Possible, assumed or actual source nuclides (mother nuclides, parent nuclides). If applicable, the corresponding decay modes can be found in the data for the respective starting nuclide.
7 - isotope notation in short form.
8 - decay: half-live of the Calcium isotope (a = years; ; d = days; h = hours; min = minutes; s = seconds).
9 - decay mode: type of decay into the respective daughter nuclides with n = neutron emission; p = proton emission; α = alpha decay; β- = beta minus decay with electron emission; EC = electron capture; β+ = positron emission; ε = β+ and/or EC; Iso = isomeric transition; CD = cluster decay; SF = spontaneous decay.
10 - decay probability in percent (%).
11 - decay energy; Particle energy related to decay type.
12 - other information and notes: AL = Adopted Levels (link to external data [1]).
Miscellaneous:
()- Numbers in brackets: uncertainty to represent the spread of the reported value.
~ - Theoretical values or systematic trends.
- unlisted-: Nuclides that have already been mentioned in the literature but for some reason can no longer be found in the current nuclide tables because their discovery e.g. has not confirmed.
| Nuclide quantity 1) spin | Nuclear magnetic moment μ/μN | Gyromagnetic ratio {Quadrupole moment} | Resonant frequency v0 bei 1 T | Relative sensitivity H0 = const. v0 = const. 3) |
|---|---|---|---|---|
| 43Ca 0,135(10) % 7/2- | -1,31733(6) | - 1,8025 {- 0,0408(8)} | 2,8697 | 0,00643 1,4154 |
1) Quantity Percentage of natural occurrence.
2) Gyromagnetic ratio: 107 rad T-1 s-1
Quadrupole moment: Q [barn] = [100 fm2]
3) Related to 1H = 1,000.
According to the Radiation Protection Ordinance (StrlSchV 2018, Germany), the following values (columns 1 to 7) apply to the handling of Calcium radionuclides:
| Nuclide | Limit Value | HASS limit | SC | Daughter Nuclides | Half-life | |
|---|---|---|---|---|---|---|
| Ca-41 | 107 Bq | 100 Bq/g | Unbegrenzt (UL) | 100000 a | ||
| Ca-45+ | 107 Bq | 1004 Bq/g | 100 TBq | 100 Bq/cm2 | 163.0 d | |
| Ca-47+ | 106 Bq | 10 Bq/g | 0,06 TBq | 1 Bq/cm2 | 4.5 d | |
(HASS = High-Activity Sealed Radioactive Sources; SC = surface contamination)
Properties of the Calcium nucleides
[1] - NuDat: National Nuclear Data Center, Brookhaven National Laboratory, based on ENSDF and the Nuclear Wallet Cards.
[2] - G. Audi et. al.: The NUBASE evaluation of nuclear and decay properties. Nuclear Physics, (2003), DOI 10.1016/j.nuclphysa.2003.11.001.
[3] - Live Chart of Nuclides. Nuclear structure and decay data.
Calcium: NMR properties - 43Ca-NMR
[4] - N. J. Stone: Table of nuclear magnetic dipole and electric quadrupole moments. Atomic Data and Nuclear Data Tables, (2005), DOI 10.1016/j.adt.2005.04.001.
[5] - Pekka Pyykkö: Year-2008 nuclear quadrupole moments. Molecular Physics, (2008), DOI 10.1080/00268970802018367.
[6] - Pekka Pyykkö: Year-2017 nuclear quadrupole moments. Molecular Physics, (2018), DOI 10.1080/00268976.2018.1426131.
[7] - N. J. Stone: Table of recommended nuclear magnetic dipole moments. IAEA, (2019).
More sources:
[8] - Isotopic abundances, atomic weights and isotopic masses: see respective keyword.
[9] - S. Amos, J. L.Gross, M. Thoennessen:
Discovery of the calcium, indium, tin, and platinum isotopes.
In: Atomic Data and Nuclear Data Tables, (2011), DOI 10.1016/j.adt.2011.03.001.
[10] - NN:
Bindungsenergien exotischer Calcium-Kerne.
In: Internetchemie News, (2013).
[11] - NN:
Ladungsradien protonenreicher Calcium-Isotope vermessen.
In: Internetchemie News, (2019).
Last update: 2022-12-12
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