Isotopes of chlorine
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Standard atomic weight Ar°(Cl) | ||||||||||||||||||||||||||||
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Chlorine (17Cl) has 25 isotopes, ranging from 28Cl to 52Cl, and two isomers, 34mCl and 38mCl. There are two stable isotopes, 35Cl (75.8%) and 37Cl (24.2%), giving chlorine a standard atomic weight of 35.45. The longest-lived radioactive isotope is 36Cl, which has a half-life of 301,000 years. All other isotopes have half-lives under 1 hour, many less than one second. The shortest-lived are proton-unbound 29Cl and 30Cl, with half-lives less than 10 picoseconds and 30 nanoseconds, respectively; the half-life of 28Cl is unknown.
List of isotopes
Nuclide [n 1] |
Z | N | Isotopic mass (Da)[4] [n 2][n 3] |
Half-life[1] [n 4] |
Decay mode[1] [n 5] |
Daughter isotope [n 6] |
Spin and parity[1] [n 7][n 4] |
Natural abundance (mole fraction) | |||||||||||
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Excitation energy | Normal proportion[1] | Range of variation | |||||||||||||||||
28Cl[5] | 17 | 11 | 28.03035(54)# | p | 27S | 1+# | |||||||||||||
29Cl | 17 | 12 | 29.01505(20)# | 5.4(19) zs | p | 28S | (1/2+) | ||||||||||||
30Cl | 17 | 13 | 30.005018(26) | <50 ns[5] | p | 29S | 3+# | ||||||||||||
31Cl | 17 | 14 | 30.9924481(37) | 190(1) ms | β+ (97.6%) | 31S | 3/2+ | ||||||||||||
β+, p (2.4%) | 30P | ||||||||||||||||||
32Cl | 17 | 15 | 31.98568461(60) | 298(1) ms | β+ (99.92%) | 32S | 1+ | ||||||||||||
β+, α (0.054%) | 28Si | ||||||||||||||||||
β+, p (0.026%) | 31P | ||||||||||||||||||
33Cl | 17 | 16 | 32.97745199(42) | 2.5038(22) s | β+ | 33S | 3/2+ | ||||||||||||
34Cl | 17 | 17 | 33.973762490(52) | 1.5267(4) s | β+ | 34S | 0+ | ||||||||||||
34mCl | 146.360(27) keV | 31.99(3) min | β+ (55.4%) | 34S | 3+ | ||||||||||||||
IT (44.6%) | 34Cl | ||||||||||||||||||
35Cl | 17 | 18 | 34.968852694(38) | Stable | 3/2+ | 0.758(2) | |||||||||||||
36Cl[n 8] | 17 | 19 | 35.968306822(38) | 3.013(15)×105 y | β− (98.1%) | 36Ar | 2+ | 7×10−13[6][7][n 9] | |||||||||||
β+ (1.9%) | 36S | ||||||||||||||||||
37Cl | 17 | 20 | 36.965902573(55) | Stable | 3/2+ | 0.242(2) | |||||||||||||
38Cl | 17 | 21 | 37.96801041(11) | 37.230(14) min | β− | 38Ar | 2− | ||||||||||||
38mCl | 671.365(8) keV | 715(3) ms | IT | 38Cl | 5− | ||||||||||||||
39Cl | 17 | 22 | 38.9680082(19) | 56.2(6) min | β− | 39Ar | 3/2+ | ||||||||||||
40Cl | 17 | 23 | 39.970415(34) | 1.35(3) min | β− | 40Ar | 2− | ||||||||||||
41Cl | 17 | 24 | 40.970685(74) | 38.4(8) s | β− | 41Ar | (1/2+) | ||||||||||||
42Cl | 17 | 25 | 41.973342(64) | 6.8(3) s | β− | 42Ar | (2−) | ||||||||||||
β−, n? | 41Ar | ||||||||||||||||||
43Cl | 17 | 26 | 42.974064(66) | 3.13(9) s | β− | 43Ar | (3/2+) | ||||||||||||
β−, n? | 42Ar | ||||||||||||||||||
44Cl | 17 | 27 | 43.978015(92) | 0.56(11) s | β− (>92%) | 44Ar | (2-) | ||||||||||||
β−, n? (<8%) | 43Ar | ||||||||||||||||||
45Cl | 17 | 28 | 44.98039(15) | 513(36) ms[8] | β− (76%) | 45Ar | (3/2+) | ||||||||||||
β−, n (24%) | 44Ar | ||||||||||||||||||
46Cl | 17 | 29 | 45.98525(10) | 232(2) ms | β−, n (60%) | 45Ar | 2-# | ||||||||||||
β− (40%) | 46Ar | ||||||||||||||||||
β−, 2n? | 44Ar | ||||||||||||||||||
47Cl | 17 | 30 | 46.98972(22)# | 101(5) ms | β− (>97%) | 47Ar | 3/2+# | ||||||||||||
β−, n? (<3%) | 46Ar | ||||||||||||||||||
β−, 2n? | 45Ar | ||||||||||||||||||
48Cl | 17 | 31 | 47.99541(54)# | 30# ms [>200 ns] |
β−? | 48Ar | |||||||||||||
β−, n? | 47Ar | ||||||||||||||||||
β−, 2n? | 46Ar | ||||||||||||||||||
49Cl | 17 | 32 | 49.00079(43)# | 35# ms [>200 ns] |
β−? | 49Ar | 3/2+# | ||||||||||||
β−, n? | 48Ar | ||||||||||||||||||
β−, 2n? | 47Ar | ||||||||||||||||||
50Cl | 17 | 33 | 50.00827(43)# | 10# ms [>620 ns] |
β− | 50Ar | |||||||||||||
β−, n? | 49Ar | ||||||||||||||||||
β−, 2n? | 48Ar | ||||||||||||||||||
51Cl | 17 | 34 | 51.01534(75)# | 5# ms [>200 ns] |
β−? | 51Ar | 3/2+# | ||||||||||||
β−, n? | 50Ar | ||||||||||||||||||
β−, 2n? | 49Ar | ||||||||||||||||||
52Cl | 17 | 35 | 52.02400(75)# | 2# ms [>400 ns] |
β−? | 52Ar | |||||||||||||
β−, n? | 51Ar | ||||||||||||||||||
β−, 2n? | 50Ar | ||||||||||||||||||
This table header & footer: |
- ^ mCl – Excited nuclear isomer.
- ^ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
- ^ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
- ^ a b # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
- ^
Modes of decay:
IT: Isomeric transition n: Neutron emission p: Proton emission - ^ Bold symbol as daughter – Daughter product is stable.
- ^ ( ) spin value – Indicates spin with weak assignment arguments.
- ^ Used in radiodating water
- ^ Cosmogenic nuclide
Chlorine-36
Trace amounts of radioactive 36Cl exist in the environment, in a ratio of about 7×10−13 to 1 with stable isotopes. 36Cl is produced in the atmosphere by spallation of 36Ar by interactions with cosmic ray protons. In the subsurface environment, 36Cl is generated primarily as a result of neutron capture by 35Cl or muon capture by 40Ca. 36Cl decays to either 36S (1.9%) or to 36Ar (98.1%), with a combined half-life of 308,000 years. The half-life of this hydrophilic nonreactive isotope makes it suitable for geologic dating in the range of 60,000 to 1 million years. Additionally, large amounts of 36Cl were produced by neutron irradiation of seawater during atmospheric detonations of nuclear weapons between 1952 and 1958. The residence time of 36Cl in the atmosphere is about 1 week. Thus, as an event marker of 1950s water in soil and ground water, 36Cl is also useful for dating waters less than 50 years before the present. 36Cl has seen use in other areas of the geological sciences, forecasts, and elements. In chloride-based molten salt reactors the production of 36
Cl by neutron capture is an inevitable consequence of using natural isotope mixtures of chlorine (i.e. Those containing 35
Cl). This produces a long lived radioactive product which has to be stored or disposed off. Isotope separation to produce pure 37
Cl can vastly reduce 36
Cl production, but a small amount might still be produced by (n,2n) reactions involving fast neutrons.
Chlorine-37
Stable chlorine-37 makes up about 24.23% of the naturally occurring chlorine on earth. Variation occurs as chloride mineral deposits have a slightly elevated chlorine-37 balance over the average found in sea water and halite deposits.[citation needed]
References
- ^ a b c d e 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.
- ^ "Standard Atomic Weights: Chlorine". CIAAW. 2009.
- ^ 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.
- ^ 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.
- ^ a b Mukha, I.; et al. (2018). "Deep excursion beyond the proton dripline. I. Argon and chlorine isotope chains". Physical Review C. 98 (6): 064308–1–064308–13. arXiv:1803.10951. Bibcode:2018PhRvC..98f4308M. doi:10.1103/PhysRevC.98.064308. S2CID 119384311.
- ^ M. Zreda; et al. (1991). "Cosmogenic chlorine-36 production rates in terrestrial rocks". Earth and Planetary Science Letters. 105 (1–3): 94–109. Bibcode:1991E&PSL.105...94Z. doi:10.1016/0012-821X(91)90123-Y.
- ^ M. Sheppard and M. Herod (2012). "Variation in background concentrations and specific activities of 36Cl, 129I and U/Th-series radionuclides in surface waters". Journal of Environmental Radioactivity. 106: 27–34. doi:10.1016/j.jenvrad.2011.10.015. PMID 22304997.
- ^ Bhattacharya, Soumik; Tripathi, Vandana; Tabor, S. L.; Volya, A.; Bender, P. C.; Benetti, C.; Carpenter, M. P.; Carroll, J. J.; Chester, A.; Chiara, C. J.; Childers, K.; Clark, B. R.; Crider, B. P.; Harke, J. T.; Jain, R.; Liddick, S. N.; Lubna, R. S.; Luitel, S.; Longfellow, B.; Mogannam, M. J.; Ogunbeku, T. H.; Perello, J.; Richard, A. L.; Rubino, E.; Saha, S.; Shehu, O. A.; Unz, R.; Xiao, Y.; Zhu, Yiyi (2023-08-18). "β− decay of neutron-rich 45Cl located at the magic number N=28" (PDF). Physical Review C. 108 (2). American Physical Society (APS): 024312. doi:10.1103/physrevc.108.024312. ISSN 2469-9985.