Element 16 — Sulfur (S) — Z = 16

Notation: mass number as a left superscript (e.g., ³⁵S).
Columns: Isotope | Z | A | Stable? | Half‑life | Decay mode(s) | Daughter | Radiation | Origin | Uses | Notes.
Scope: Sulfur has 23 known isotopes with A = 27–49; four are stable (³²S, ³³S, ³⁴S, ³⁶S). Numeric half‑lives/branches below follow the NUBASE/AME‑backed evaluated table; LiveChart/NuDat are the primary authorities. (Wikipedia, www-nds.iaea.org, nndc.bnl.gov)

IsotopeZAStable?Half‑lifeDecay mode(s)DaughterRadiationOriginUsesNotes
²⁷S1627Unstable16.3 msβ⁺p 61%; β⁺ 36%; β⁺2p 3%²⁶Si; ²⁷P; ²⁵Alβ⁺; pSyntheticResearch (dripline)Trend/data‑evaluated branches. (Wikipedia)
²⁸S1628Unstable125 msβ⁺ 79.3%; β⁺p 20.7%²⁸P; ²⁷Siβ⁺; pSyntheticResearch— (Wikipedia)
²⁹S1629Unstable188 msβ⁺ 53.6%; β⁺p 46.4%²⁹P; ²⁸Siβ⁺; pSyntheticResearch— (Wikipedia)
³⁰S1630Unstable1.1798 sβ⁺³⁰Pβ⁺Syntheticβ⁺ standards; reaction tests— (Wikipedia)
³¹S1631Unstable2.553 sβ⁺³¹Pβ⁺Synthetic (activation/accelerators)β⁺ spectroscopy— (Wikipedia)
³²S1632StableNatural (major)Stable‑isotope geochemistry (δ³⁴S); IRMSDominant natural isotope. (Wikipedia, ACS Publications)
³³S1633StableNatural (trace)Mass‑independent fractionation studies (Δ³³S); niche NMRSpin 3/2; rare. (Wikipedia)
³⁴S1634StableNatural (minor)δ³⁴S reference ratio in IRMSAbundance varies by environment. (Wikipedia)
³⁵S1635Unstable87.37 dβ⁻ → ³⁵Cl (100%)³⁵Clβ⁻ (no γ)Natural trace (cosmogenic from ⁴⁰Ar) & SyntheticTracer: hydrology (rain/groundwater), soil–plant studies; biochemistry (radiolabel S‑amino acids)Widely used low‑energy β‑emitter. (Wikipedia, USC Environmental Health & Safety, IAEA Publications, ResearchGate)
³⁶S1636StableNatural (ultra‑trace)Baseline in δ³⁶S studiesVery low natural abundance. (Wikipedia)
³⁷S1637Unstable5.05 minβ⁻ → ³⁷Cl (100%)³⁷Clβ⁻SyntheticActivation & β‑decay benchmarksOften produced via Cl reactions. (Wikipedia, periodictable.com)
³⁸S1638Unstable170.3 minβ⁻ → ³⁸Cl (100%)³⁸Clβ⁻SyntheticTracer/decay studiesSecond‑longest‑lived S radioisotope. (Wikipedia)
³⁹S1639Unstable11.5 sβ⁻ → ³⁹Cl³⁹Clβ⁻SyntheticResearch— (Wikipedia)
⁴⁰S1640Unstable8.8 sβ⁻ → ⁴⁰Cl⁴⁰Clβ⁻SyntheticResearch— (Wikipedia)
⁴¹S1641Unstable1.99 sβ⁻ → ⁴¹Cl⁴¹Clβ⁻SyntheticResearch— (Wikipedia)
⁴²S1642Unstable1.016 sβ⁻ (> 96%); β⁻,n (< 1%)⁴²Cl; ⁴¹Clβ⁻; delayed nSyntheticβ‑delayed‑n studies— (Wikipedia)
⁴³S1643Unstable265 msβ⁻ 60%; β⁻,n 40%⁴³Cl; ⁴²Clβ⁻; delayed nSyntheticβ‑delayed‑n benchmarks⁴³ᵐS: 415 ns IT isomer. (Wikipedia)
⁴⁴S1644Unstable100 msβ⁻ 82%; β⁻,n 18%⁴⁴Cl; ⁴³Clβ⁻; delayed nSyntheticN=28 structure; shape‑coexistence case⁴⁴ᵐS: 2.62 µs IT; deformed/prolate–spherical coexistence at N=28. (Wikipedia, Physical Review Link Manager, arXiv)
⁴⁵S1645Unstable68 msβ⁻,n 54%; β⁻ 46%⁴⁴Cl; ⁴⁵Clβ⁻; delayed nSyntheticNeutron‑rich decay— (Wikipedia)
⁴⁶S1646Unstable50 msβ⁻ → ⁴⁶Cl⁴⁶Clβ⁻SyntheticStructure (N>28)— (Wikipedia)
⁴⁷S1647Unstable24 ms (#; > 200 ns)β⁻? (trend)⁴⁷Cl (expected)β⁻ (expected)SyntheticEdge‑of‑stability testsEvaluated from neighboring systematics (#). (Wikipedia)
⁴⁸S1648Unstable10 ms (#; > 200 ns)β⁻? (trend)⁴⁸Cl (expected)β⁻ (expected)SyntheticEdge‑of‑stability testsTrend‑estimated (#). (Wikipedia)
⁴⁹S1649Unstable4 ms (#; > 400 ns)β⁻? (trend)⁴⁹Cl (expected)β⁻ (expected)SyntheticHeaviest observed STrend‑estimated (#). (Wikipedia)

Radiation key: β⁺/EC → annihilation γ (511 keV); β⁻ (electron); β⁻,n = β decay with delayed neutron; p/2p = prompt proton(s) from proton‑unbound branches; IT = isomeric transition γ.
Applied highlights: ³⁵S (87.37 d) is the workhorse sulfur radioisotope for hydrology, soil–plant studies, and biochemical radiolabeling; its low‑energy β makes handling practical under standard lab controls. Stable‑isotope work relies on δ³⁴S (and Δ³³S) by IRMS. (IAEA Publications, USC Environmental Health & Safety, ResearchGate, ACS Publications)


Totals — Sulfur (Z = 16)

  • Stable4  (³²S, ³³S, ³⁴S, ³⁶S)
  • Unstable19  (²⁷–³¹S, ³⁵S, ³⁷–⁴⁹S)
  • Total isotopes23. (Wikipedia)

Running cumulative totals (H → S, Z = 1…16)

  • Cumulative total isotopes274  (H: 7 • He: 8 • Li: 10 • Be: 11 • B: 15 • C: 14 • N: 15 • O: 18 • F: 19 • Ne: 20 • Na: 21 • Mg: 22 • Al: 24 • Si: 25 • P: 22 • S: 23)
  • Cumulative stable33  (H: 2 • He: 2 • Li: 2 • Be: 1 • B: 2 • C: 2 • N: 2 • O: 3 • F: 1 • Ne: 3 • Na: 1 • Mg: 3 • Al: 1 • Si: 3 • P: 1 • S: 4)
  • Cumulative unstable241

Sources & cross‑checks

  • Isotopes of sulfur — complete per‑nuclide list (A = 27–49) with half‑lives and branches; cites NUBASE2020/AME2020. (Wikipedia)
  • IAEA LiveChart of Nuclides (ENSDF backbone) and NNDC NuDat 3 — authoritative decay‑mode/half‑life look‑ups used for verification. (www-nds.iaea.org, nndc.bnl.gov)
  • S‑35 properties & lab use (β energy, handling): USC EHS; soil–plant tracer guidance (IAEA TCS‑20); hydrology applications (recent methods). (USC Environmental Health & Safety, IAEA Publications, ResearchGate)
  • Stable‑isotope analysis (δ³⁴S, Δ³³S) — IRMS methods & sulfur isotope biogeochemistry overview. (ACS Publications, Wikipedia)
  • Structure note (⁴⁴S) — prolate–spherical shape coexistence at N = 28 (PRL 2010; classic & modern reviews). (Physical Review Link Manager, arXiv)

Next: Chlorine — Cl (Z = 17).

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