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24 isotopes and some nuclear isomers of the chemical element chlorine are known. The individual nuclides differ in the number of neutrons in the atomic nucleus; What all Cl isotopes have in common is the number of protons and - in the uncharged, neutral state - of electrons: 17.
Natural chlorine deposits are composed of the stable isotopes chlorine-35 and chlorine-37 in a 3:1 ratio and traces (7 x 10-13 atoms to 1 stable chlorine atom) of the radioisotope chlorine-36 together; the latter is mainly produced by the effects of cosmic radiation on 40Ar and 36Ar and radioactively decays to 36Ar and with a half-life of 308000 years 36p. 36Cl is used in geological dating.
| Atomic Mass ma | Quantity | Half-life | Spin | |
| Chlorine Isotopic mixture | 35,45 u | 100 % | ||
| Isotope 36Cl | 35,96830682(4) u | traces | 3.013(15) × 105 a | 2+ |
| Isotope 37Cl | 36,9659026(4) u | 24,2 % | stable | 3/2+ |
| Isotope 35Cl | 34,9688527(3) u | 75,80(17) % | stable | 3/2+ |
The atomic mass varies between 35.446 and 35.457 u, corresponding to the fluctuations in the isotopic composition of natural chlorine.
All other chlorine isotopes are radioactive and decay with half-lives of less than 1 hour.
| Isotope Nuclide | E | N | Atomic Mass [Nuclear Mass] {Mass Excess} | Spin I (h/2π) | Parent |
|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 5 | 6 |
| Chlorine-28 | 2817Cl | 11 | 28.02954(64) u [28.0202143 u] {27.51633 MeV} | 1+ | |
| Chlorine-29 | 2917Cl | 12 | 29.01413(20) u [29.0048043 u] {13.16201 MeV} | (1/2+) | |
| Chlorine-30 | 3017Cl | 13 | 30.00477(21) u [29.9954443 u] {4.44323 MeV} | (3+) | |
| Chlorine-31 | 3117Cl | 14 | 30.992448(4) u [30.9831223 u] {-7.03464 MeV} | 3/2+ | 31Ar |
| Chlorine-32 | 3217Cl | 15 | 31.9856846(6) u [31.9763589 u] {-13.33471 MeV} | 1+ | 32Ar |
| Chlorine-33 | 3317Cl | 16 | 32.9774520(4) u [32.9681263 u] {-21.00333 MeV} | 3/2+ | 33Ar 35Ca |
| Chlorine-34 | 3417Cl | 17 | 33.97376249(5) u [33.9644368 u] {-24.44008 MeV} | 0+ | 34Ar 35K |
| Chlorine-34m | 34m17Cl | 17 | 33.97376249(5) u [33.9644368 u] {-24.44008 MeV} | 3+ | |
| Chlorine-35 | 3517Cl | 18 | 34.9688527(3) u [34.959527 u] {-29.01352 MeV} | 3/2+ | 35Ar 35S 36K |
| Chlorine-36 | 3617Cl | 19 | 35.96830682(4) u [35.9589811 u] {-29.52201 MeV} | 2+ | |
| Chlorine-37 | 3717Cl | 20 | 36.9659026(4) u [36.9565769 u] {-31.76152 MeV} | 3/2+ | 37Ar 37S |
| Chlorine-38 | 3817Cl | 21 | 37.96801041(11) u [37.9586847 u] {-29.79811 MeV} | 2- | 38S |
| Chlorine-38m | 38m17Cl | 21 | 37.96801041(11) u [37.9586847 u] {-29.79811 MeV} | 5- | |
| Chlorine-39 | 3917Cl | 22 | 38.9680082(19) u [38.9586825 u] {-29.80017 MeV} | 3/2+ | 39S |
| Chlorine-40 | 4017Cl | 23 | 39.97042(3) u [39.9610943 u] {-27.55359 MeV} | 2- | 40S |
| Chlorine-41 | 4117Cl | 24 | 40.97068(7) u [40.9613543 u] {-27.3114 MeV} | (1/2+) | 41S 42S |
| Chlorine-42 | 4217Cl | 25 | 41.97334(6) u [41.9640143 u] {-24.83363 MeV} | (2-) | 42S 43S |
| Chlorine-43 | 4317Cl | 26 | 42.97406(7) u [42.9647343 u] {-24.16295 MeV} | (1/2+) | 43S 44S |
| Chlorine-44 | 4417Cl | 27 | 43.97812(15) u [43.9687943 u] {-20.38109 MeV} | (2-) | 44S |
| Chlorine-45 | 4517Cl | 28 | 44.98039(15) u [44.9710643 u] {-18.2666 MeV} | (1/2+) | |
| Chlorine-46 | 4617Cl | 29 | 45.98512(22) u [45.9757943 u] {-13.86063 MeV} | (2-) | |
| Chlorine-47 | 4717Cl | 30 | 46.98950(43) u [46.9801743 u] {-9.78069 MeV} | 3/2+ | |
| Chlorine-48 | 4817Cl | 31 | 47.99541(54) u [47.9860843 u] {-4.27556 MeV} | ||
| Chlorine-49 | 4917Cl | 32 | 49.00101(64) u [48.9916843 u] {0.94081 MeV} | 3/2+ | |
| Chlorine-50 | 5017Cl | 33 | 50.00831(64) u [49.9989843 u] {7.74072 MeV} | ||
| Chlorine-51 | 5117Cl | 34 | 51.01534(75) u [51.0060143 u] {14.28912 MeV} | (3/2+) |
| Isotope | Radioactive Decay | Extern | |||
|---|---|---|---|---|---|
| Half-life | Decay Mode | Probability | Energy | ||
| 7 | 8 | 9 | 10 | 11 | 12 |
| Cl-28 | p → 27S | AL | |||
| Cl-29 | 20 ns | p → 28S | AL | ||
| Cl-30 | 30 ns | p → 29S | AL | ||
| Cl-31 | 190(1) ms | β+ → 31S β+, p → 30P | 97.6 % 2.4(2) % | 11.9769 MeV 5.844 MeV | AL |
| Cl-32 | 298(1) ms | EC/β+ → 32S ε, p → 31P EC, α → 28Si | 99.92 % 0.26 % 0.054 % | 12.6804 MeV 3.822 MeV 5.738 MeV | AL |
| Cl-33 | 2.511(4) s | EC/β+ → 33S | 100 % | 5.58259 MeV | AL |
| Cl-34 | 1.5266(4) s | EC/β+ → 34S | 100 % | 5.49163 MeV | AL |
| Cl-34m | 31.99(3) min | EC/β+ → 34S Iso → 34Cl | 55.4(6) % 44.6(6) % | 5.638 MeV 0.146 MeV | AL |
| Cl-35 | stable | AL | |||
| Cl-36 | 3.013(15) × 105 a | EC/β+ → 36S β- → 36Ar | 1.9(1) % 98.1(1) % | 1.14213(19) MeV 0.70953(4) MeV | AL |
| Cl-37 | stable | AL | |||
| Cl-38 | 37.230(14) min | β- → 38Ar | 100 % | 4.91671(22) MeV | AL |
| Cl-38m | 715(3) ms | Iso → 38Cl | 100 % | 0.671 MeV | AL |
| Cl-39 | 56.2(6) min | β- → 39Ar | 100 % | 3.44197 MeV | AL |
| Cl-40 | 1.35(2) min | β- → 40Ar | 100 % | 7.48208 MeV | AL |
| Cl-41 | 38.4(8) s | β- → 41Ar | 100 % | 5.76031 MeV | AL |
| Cl-42 | 6.8(3) s | β- → 42Ar | 100 % | 9.50968 MeV | AL |
| Cl-43 | 3.13(9) s | β- → 43Ar | 100 % | 7.60166 MeV | AL |
| Cl-44 | 0.56(11) s | β- → 44Ar β-, n → 43Ar | > 92 % < 8 % | 12.06806 MeV 3.33331 MeV | AL |
| Cl-45 | 413(25) ms | β- → 45Ar β-, n → 44Ar | 76(4) % 24(4) % | 11.41103 MeV 6.2422 MeV | AL |
| Cl-46 | 232(2) ms | β- → 46Ar β-, n → 45Ar | 40(9) % 60(9) % | 15.9192 MeV 7.8891 MeV | AL |
| Cl-47 | 101(6) ms | β- → 47Ar β-, n → 46Ar | 97 % < 3 % | 15.59(40) MeV 11.92(40) MeV | AL |
| Cl-48 | 200 ns | β- → 48Ar | ? | 18.00(59) MeV | AL |
| Cl-49 | 170 ns | β- → 49Ar | ? | 18.13(72) MeV | AL |
| Cl-50 | 620 ns | β- ? 50Ar β-, n,2n,3n ? | AL | ||
| Cl-51 | 200 ns | β- ? 51Ar | 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 Chlorine 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 Chlorine 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) |
|---|---|---|---|---|
| 35Cl 75,80(17) % 3/2+ | +0,82170(2) | 2,624 {- 0,08112} | 4,1765 | 0,00472 0,4905 |
| 37Cl 24,2 % 3/2+ | +0,68400(1) | 2,1842 {- 0,06393} | 3,4765 | 0,00272 0,4083 |
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 Chlorine radionuclides:
| Nuclide | Limit Value | HASS limit | SC | Daughter Nuclides | Half-life | |
|---|---|---|---|---|---|---|
| Cl-36 | 106 Bq | 1 Bq/g | 20 TBq | 100 Bq/cm2 | 300000 a | |
| Cl-38 | 105 Bq | 10 Bq/g | 0,05 TBq | 1 Bq/cm2 | 37.2 min | |
| Cl-39 | 105 Bq | 10 Bq/g | 55.6 min | |||
(HASS = High-Activity Sealed Radioactive Sources; SC = surface contamination)
Properties of the Chlorine 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.
Chlorine: NMR properties - 35Cl-NMR, 37Cl-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.
Last update: 2022-12-12
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