Notation: mass number as a left superscript (e.g., ³⁶Cl).
Columns: Isotope | Z | A | Stable? | Half‑life | Decay mode(s) | Daughter | Radiation | Origin | Uses | Notes.
Backbone: evaluated NUBASE/ENSDF values compiled in Isotopes of chlorine; specific radionuclides cross‑checked (e.g., ³⁶Cl, ³⁸Cl). (Wikipedia, IAEA Nuclear Data Services, nndc.bnl.gov)
| Isotope | Z | A | Stable? | Half‑life | Decay mode(s) | Daughter | Radiation | Origin | Uses | Notes |
|---|---|---|---|---|---|---|---|---|---|---|
| ²⁸Cl | 17 | 28 | Unstable (unbound) | prompt; unmeasured | p | ²⁷S | protons | Synthetic | Research (extreme p‑rich) | Ground‑state proton unbound. (Wikipedia) |
| ²⁹Cl | 17 | 29 | Unstable (unbound) | 5.4(19) zs | p | ²⁸S | protons | Synthetic | Research | Width‑derived lifetime (zeptoseconds). (Wikipedia) |
| ³⁰Cl | 17 | 30 | Unstable (unbound) | < 50 ns | p | ²⁹S | protons | Synthetic | Research | Proton‑unbound resonance. (Wikipedia) |
| ³¹Cl | 17 | 31 | Unstable | 190(1) ms | β⁺ (97.6%); β⁺p (2.4%) | ³¹S; ³⁰P | β⁺; delayed p | Synthetic | β‑delayed‑p studies | — (Wikipedia) |
| ³²Cl | 17 | 32 | Unstable | 298(1) ms | β⁺ (99.92%); β⁺α (0.054%); β⁺p (0.026%) | ³²S; ²⁸Si; ³¹P | β⁺; delayed α/p | Synthetic | Reaction studies | — (Wikipedia) |
| ³³Cl | 17 | 33 | Unstable | 2.5038(22) s | β⁺ | ³³S | β⁺ | Synthetic | β⁺ spectroscopy | — (Wikipedia) |
| ³⁴Cl | 17 | 34 | Unstable | 1.5267(4) s | β⁺ | ³⁴S | β⁺ | Synthetic | β⁺ standards | ³⁴mCl isomer: 31.99 min (β⁺ 55%; IT 45%). (Wikipedia) |
| ³⁵Cl | 17 | 35 | Stable | — | — | — | — | Natural (75.8%) | Stable‑isotope geochemistry (δ³⁷Cl, IRMS); ³⁵/³⁷Cl‑NMR | Mononuclidic pair with ³⁷Cl defines Cl IRMS. (webelements.com) |
| ³⁶Cl | 17 | 36 | Unstable (natural trace) | 3.013(15)×10⁵ y | β⁻ 98.1% → ³⁶Ar; EC/β⁺ 1.9% → ³⁶S | ³⁶Ar; ³⁶S | β⁻; EC/β⁺ | Cosmogenic (atmosphere; n‑capture on ³⁵Cl) | Hydrology & exposure dating (10⁴–10⁶ y); MSR salt management | Widely used tracer; production & applications summarized by USGS. (Wikipedia, wwwrcamnl.wr.usgs.gov, USGS) |
| ³⁷Cl | 17 | 37 | Stable | — | — | — | — | Natural (24.2%) | δ³⁷Cl in environmental forensics; ³⁵/³⁷Cl‑NMR | Commercially enriched for tracer work. (webelements.com) |
| ³⁸Cl | 17 | 38 | Unstable | 37.230(14) min | β⁻ → ³⁸Ar | ³⁸Ar | β⁻; γ (from ³⁸Ar*) | Activation (salt water, reactors) & Synthetic | Activation monitor; dosimetry data available. (Wikipedia, KAERI Nuclear Data Center, MIRDSoft) | |
| ³⁹Cl | 17 | 39 | Unstable | 56.2(6) min | β⁻ → ³⁹Ar | ³⁹Ar | β⁻; γ (from ³⁹Ar*) | Synthetic | β/γ spectroscopy; activation | — (Wikipedia) |
| ⁴⁰Cl | 17 | 40 | Unstable | 1.35(3) min | β⁻ → ⁴⁰Ar | ⁴⁰Ar | β⁻ | Synthetic | Short‑lived activation product | — (Wikipedia) |
| ⁴¹Cl | 17 | 41 | Unstable | 38.4(8) s | β⁻ → ⁴¹Ar | ⁴¹Ar | β⁻ | Synthetic | Decay studies | — (Wikipedia) |
| ⁴²Cl | 17 | 42 | Unstable | 6.8(3) s | β⁻ → ⁴²Ar; β⁻, n? → ⁴¹Ar | ⁴²Ar; ⁴¹Ar | β⁻; delayed n (possible) | Synthetic | β‑delayed‑n limits | — (Wikipedia) |
| ⁴³Cl | 17 | 43 | Unstable | 3.13(9) s | β⁻ → ⁴³Ar; β⁻, n? → ⁴²Ar | ⁴³Ar; ⁴²Ar | β⁻; delayed n (possible) | Synthetic | Structure studies | — (Wikipedia) |
| ⁴⁴Cl | 17 | 44 | Unstable | 0.56(11) s | β⁻ > 92% → ⁴⁴Ar; β⁻, n? < 8% → ⁴³Ar | ⁴⁴Ar; ⁴³Ar | β⁻; delayed n (possible) | Synthetic | β‑delayed‑n benchmarks | — (Wikipedia) |
| ⁴⁵Cl | 17 | 45 | Unstable | 513(36) ms | β⁻ 76% → ⁴⁵Ar; β⁻, n 24% → ⁴⁴Ar | ⁴⁵Ar; ⁴⁴Ar | β⁻; delayed n | Synthetic | Continuum structure | — (Wikipedia) |
| ⁴⁶Cl | 17 | 46 | Unstable | 232(2) ms | β⁻, n 60% → ⁴⁵Ar; β⁻ 40% → ⁴⁶Ar (β⁻,2n?) | ⁴⁵Ar; ⁴⁶Ar (⁴⁴Ar) | β⁻; delayed n | Synthetic | Dripline approach | — (Wikipedia) |
| ⁴⁷Cl | 17 | 47 | Unstable | 101(5) ms | β⁻ > 97% → ⁴⁷Ar; β⁻, n? < 3% | ⁴⁷Ar | β⁻; delayed n (possible) | Synthetic | β‑n statistics | — (Wikipedia) |
| ⁴⁸Cl | 17 | 48 | Unstable | ≈ 30 ms (#; > 200 ns) | β⁻? (± n/2n?) | ⁴⁸Ar (…⁴⁷/⁴⁶Ar) | β⁻; delayed n? | Synthetic | Edge‑of‑stability tests | Trend/evaluation (#). (Wikipedia) |
| ⁴⁹Cl | 17 | 49 | Unstable | ≈ 35 ms (#; > 200 ns) | β⁻? (± n/2n?) | ⁴⁹Ar (…⁴⁸/⁴⁷Ar) | β⁻; delayed n? | Synthetic | Edge‑of‑stability tests | Trend/evaluation (#). (Wikipedia) |
| ⁵⁰Cl | 17 | 50 | Unstable | ≈ 10 ms (#; > 620 ns) | β⁻? (± n/2n?) | ⁵⁰Ar (…⁴⁹/⁴⁸Ar) | β⁻; delayed n? | Synthetic | Edge‑of‑stability tests | Trend/evaluation (#). (Wikipedia) |
| ⁵¹Cl | 17 | 51 | Unstable | ≈ 5 ms (#; > 200 ns) | β⁻? (± n/2n?) | ⁵¹Ar (…⁵⁰/⁴⁹Ar) | β⁻; delayed n? | Synthetic | Heaviest well‑documented | Trend/evaluation (#). (Wikipedia) |
| ⁵²Cl | 17 | 52 | Unstable | ≈ 2 ms (#; > 400 ns) | β⁻? (± n/2n?) | ⁵²Ar (…⁵¹/⁵⁰Ar) | β⁻; delayed n? | Synthetic | Most neutron‑rich observed | Trend/evaluation (#). (Wikipedia) |
Radiation key: β⁺/EC → annihilation γ (511 keV); β⁻ (electron); β⁻, n/2n = β‑decay with 1/2 delayed neutron(s); p = prompt proton emission from proton‑unbound states; IT = isomeric transition γ.
Totals — Chlorine (Z = 17)
- Stable2 (³⁵Cl, ³⁷Cl)
- Unstable23 (²⁸–³⁴Cl, ³⁶Cl, ³⁸–⁵²Cl)
- Total isotopes25. (Wikipedia)
Running cumulative totals (H → Cl, Z = 1…17)
- Cumulative total isotopes299 (prior through S: 274 • Cl: +25)
- Cumulative stable35 (prior through S: 33 • Cl: +2)
- Cumulative unstable264
Sources & cross‑checks
- Isotopes of chlorine — per‑nuclide half‑lives, modes & branches (A = 28–52); cites NUBASE2020/AME and ENSDF. (Wikipedia)
- IAEA LiveChart of Nuclides (ENSDF backbone) and NNDC NuDat 3 — authoritative decay/structure look‑ups. (IAEA Nuclear Data Services, nndc.bnl.gov)
- ³⁶Cl: precise t½ = 3.013(15)×10⁵ y and decay branches (β⁻ 98.1% → ³⁶Ar; EC/β⁺ 1.9% → ³⁶S); USGS hydrology & exposure‑dating overview. (Wikipedia, USGS)
- ³⁸Cl: evaluated t½ ≈ 37.24 min, β⁻ → ³⁸Ar; dosimetric sheet; KAERI nuclide page. (MIRDSoft, KAERI Nuclear Data Center)
- Stable‑isotope & NMR context (³⁵/³⁷Cl): WebElements isotope data and DOE/NIDC enrichment notes. (webelements.com, National Isotope Development Center)
Next: Argon — Ar (Z = 18).
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