Английская Википедия:Isotopes of calcium

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Шаблон:Short description Шаблон:More citations needed Шаблон:Infobox calcium isotopes

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 for all practical purposes it can be considered 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, radioactive 41Ca, which has a half-life of 99,400 years. Unlike cosmogenic isotopes that are produced in the atmosphere, 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 sufficiently strong. 41Ca has received much attention in stellar studies because it decays to 41K, a critical indicator of solar system anomalies. The most stable artificial radioisotopes are 45Ca with a half-life of 163 days and 47Ca with a half-life of 4.5 days. All other calcium isotopes have half-lives measured in minutes or less.[1]

40Ca comprises about 97% of naturally occurring calcium. 40Ca is also one of the daughter products of 40K decay, along with 40Ar. While K–Ar dating has been used extensively in the geological sciences, the prevalence of 40Ca in nature has impeded its use in dating. Techniques using mass spectrometry and a double spike isotope dilution have been used for K–Ca age dating.

List of isotopes

Шаблон:Isotopes table |- | rowspan=3|35Ca | rowspan=3 style="text-align:right" | 20 | rowspan=3 style="text-align:right" | 15 | rowspan=3|35.00557(22)# | rowspan=3|25.7(2) ms | β+, p (95.8%) | 34Ar | rowspan=3|1/2+# | rowspan=3| | rowspan=3| |- | β+, 2p (4.2%) | 33Cl |- | β+ (rare) | 35K |- | rowspan=2|36Ca | rowspan=2 style="text-align:right" | 20 | rowspan=2 style="text-align:right" | 16 | rowspan=2|35.993074(43) | rowspan=2|100.9(13) ms | β+, p (51.2%) | 35Ar | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | β+ (48.8%) | 36K |- | rowspan=2|37Ca | rowspan=2 style="text-align:right" | 20 | rowspan=2 style="text-align:right" | 17 | rowspan=2|36.98589785(68) | rowspan=2|181.0(9) ms | β+, p (76.8%) | 36Ar | rowspan=2|3/2+ | rowspan=2| | rowspan=2| |- | β+ (23.2%) | 37K |- | 38Ca | style="text-align:right" | 20 | style="text-align:right" | 18 | 37.97631922(21) | 443.70(25) ms | β+ | 38K | 0+ | | |- | 39Ca | style="text-align:right" | 20 | style="text-align:right" | 19 | 38.97071081(64) | 860.3(8) ms | β+ | 39K | 3/2+ | | |- | 40Ca[n 1] | style="text-align:right" | 20 | style="text-align:right" | 20 | 39.962590850(22) | colspan=3 align=center|Observationally stable[n 2] | 0+ | 0.9694(16) | 0.96933–0.96947 |- | 41Ca | style="text-align:right" | 20 | style="text-align:right" | 21 | 40.96227791(15) | 9.94(15)×104 y | EC | 41K | 7/2− | Trace[n 3] | |- | 42Ca | style="text-align:right" | 20 | style="text-align:right" | 22 | 41.95861778(16) | colspan=3 align=center|Stable | 0+ | 0.00647(23) | 0.00646–0.00648 |- | 43Ca | style="text-align:right" | 20 | style="text-align:right" | 23 | 42.95876638(24) | colspan=3 align=center|Stable | 7/2− | 0.00135(10) | 0.00135–0.00135 |- | 44Ca | style="text-align:right" | 20 | style="text-align:right" | 24 | 43.95548149(35) | colspan=3 align=center|Stable | 0+ | 0.0209(11) | 0.02082–0.02092 |- | 45Ca | style="text-align:right" | 20 | style="text-align:right" | 25 | 44.95618627(39) | 162.61(9) d | β− | 45Sc | 7/2− | | |- | 46Ca | style="text-align:right" | 20 | style="text-align:right" | 26 | 45.9536877(24) | colspan=3 align=center|Observationally stable[n 4] | 0+ | 4×10−5 | 4×10−5–4×10−5 |- | 47Ca | style="text-align:right" | 20 | style="text-align:right" | 27 | 46.9545411(24) | 4.536(3) d | β− | 47Sc | 7/2− | | |- | 48Ca[n 5][n 6] | style="text-align:right" | 20 | style="text-align:right" | 28 | 47.952522654(18) | 5.6(10)×1019 y|| β−β−[n 7]Шаблон:Refn | 48Ti | 0+ | 0.00187(21) | 0.00186–0.00188 |- | 49Ca | style="text-align:right" | 20 | style="text-align:right" | 29 | 48.95566263(19) | 8.718(6) min | β− | 49Sc | 3/2− | | |- | 50Ca | style="text-align:right" | 20 | style="text-align:right" | 30 | 49.9574992(17) | 13.45(5) s | β− | 50Sc | 0+ | | |- | rowspan=2|51Ca | rowspan=2 style="text-align:right" | 20 | rowspan=2 style="text-align:right" | 31 | rowspan=2|50.96099566(56) | rowspan=2|10.0(8) s | β− | 51Sc | rowspan=2|3/2− | rowspan=2| | rowspan=2| |- | β−, n? | 50Sc |- | rowspan=2|52Ca | rowspan=2 style="text-align:right" | 20 | rowspan=2 style="text-align:right" | 32 | rowspan=2|51.96321365(72) | rowspan=2|4.6(3) s | β− (>98%) | 52Sc | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | β−, n (<2%) | 51Sc |- | rowspan=2|53Ca | rowspan=2 style="text-align:right" | 20 | rowspan=2 style="text-align:right" | 33 | rowspan=2|52.968451(47) | rowspan=2|461(90) ms | β− (60%) | 53Sc | rowspan=2|1/2−# | rowspan=2| | rowspan=2| |- | β−, n (40%) | 52Sc |- | rowspan=3|54Ca | rowspan=3 style="text-align:right" | 20 | rowspan=3 style="text-align:right" | 34 | rowspan=3|53.972989(52) | rowspan=3|90(6) ms | β− | 54Sc | rowspan=3|0+ | rowspan=3| | rowspan=3| |- | β−, n? | 53Sc |- | β−, 2n? | 52Sc |- | rowspan=3|55Ca | rowspan=3 style="text-align:right" | 20 | rowspan=3 style="text-align:right" | 35 | rowspan=3|54.97998(17) | rowspan=3|22(2) ms | β− | 55Sc | rowspan=3|5/2−# | rowspan=3| | rowspan=3| |- | β−, n? | 54Sc |- | β−, 2n? | 53Sc |- | rowspan=3|56Ca | rowspan=3 style="text-align:right" | 20 | rowspan=3 style="text-align:right" | 36 | rowspan=3|55.98550(27) | rowspan=3|11(2) ms | β− | 56Sc | rowspan=3|0+ | rowspan=3| | rowspan=3| |- | β−, n? | 55Sc |- | β−, 2n? | 54Sc |- | rowspan=3|57Ca | rowspan=3 style="text-align:right" | 20 | rowspan=3 style="text-align:right" | 37 | rowspan=3|56.99296(43)# | rowspan=3|8# ms [>620 ns] | β−? | 57Sc | rowspan=3|5/2−# | rowspan=3| | rowspan=3| |- | β−, n? | 56Sc |- | β−, 2n? | 55Sc |- | rowspan=3|58Ca | rowspan=3 style="text-align:right" | 20 | rowspan=3 style="text-align:right" | 38 | rowspan=3|57.99836(54)# | rowspan=3|4# ms [>620 ns] | β−? | 58Sc | rowspan=3|0+ | rowspan=3| | rowspan=3| |- | β−, n? | 57Sc |- | β−, 2n? | 56Sc |- | rowspan=3|59Ca | rowspan=3 style="text-align:right" | 20 | rowspan=3 style="text-align:right" | 39 | rowspan=3|59.00624(64)# | rowspan=3|5# ms [>400 ns] | β−? | 59Sc | rowspan=3|5/2−# | rowspan=3| | rowspan=3| |- | β−, n? | 58Sc |- | β−, 2n? | 57Sc |- | rowspan=3|60Ca | rowspan=3 style="text-align:right" | 20 | rowspan=3 style="text-align:right" | 40 | rowspan=3|60.01181(75)# | rowspan=3|2# ms [>400 ns] | β−? | 60Sc | rowspan=3|0+ | rowspan=3| | rowspan=3| |- | β−, n? | 59Sc |- | β−, 2n? | 58Sc Шаблон:Isotopes table/footer

Calcium-48

Шаблон:Main

Файл:Calcium-48 carbonate.png
Around 2 g of calcium-48

Calcium-48 is a doubly magic nucleus with 28 neutrons, which is 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, although single beta decay is theoretically possible as well.[2] This decay can analyzed with the sd nuclear shell model, and it is more energetic (4.27 MeV) than any other double beta decay.[3] It can also be used as a precursor for neutron-rich and superheavy nuclei.[4][5]

Calcium-60

Calcium-60 is the heaviest known isotope Шаблон:As of.[6] First observed in 2018 at Riken alongside 59Ca and seven isotopes of other elements,[7] 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.[8] Earlier predictions had estimated the neutron drip line to occur at 60Ca, with 59Ca unbound.[7]

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.[9][10] 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.[10][11]

References

Шаблон:Reflist

Further reading

External links

Шаблон:Navbox element isotopes Шаблон:Authority control

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  1. ↑ Шаблон:Nubase 2016
  2. ↑ Шаблон:Cite journal
  3. ↑ Шаблон:Cite journal
  4. ↑ Шаблон:Cite journal
  5. ↑ Шаблон:Cite journal
  6. ↑ Ошибка цитирования Неверный тег <ref>; для сносок NUBASE2020 не указан текст
  7. ↑ 7,0 7,1 Шаблон:Cite journal
  8. ↑ Шаблон:Cite journal
  9. ↑ Шаблон:Cite journal
  10. ↑ 10,0 10,1 Шаблон:Cite journal
  11. ↑ Шаблон:Cite journal


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