Sulfur-31

Properties and data of the isotope ³¹S.

Contents

General data

Name of the isotope:Sulfur-31; S-31Symbol:³¹S or 3116SMass number A:31 (= number of nucleons)Atomic number Z:16 (= number of protons)Neutrons N:15Isotopic mass:30.97955701(25) u (atomic weight of Sulfur-31)Nuclide mass:30.9707798 u (calculated nuclear mass without electrons)Mass excess:-19.04252 MeVMass defect:0.275617242 u (per nucleus)Nuclear binding energy:256.73580722 MeV (per nucleus)
8.28180023 MeV (average binding energy per nucleon)Separation energy:S_N = 13.0546(3) MeV (first neutron)
S_P = 6.13064(24) MeV (first proton)Half-life:2.5534(18) sDecay constant λ:0.27146047644707 s^-1Specific activity α:5.449244090232 × 10⁺²¹ Bq g^-1
147276867303.58 Ci g^-1Spin and parity:
(nuclear angular momentum)1/2+Magnetic dipole moment:μ(μ_N) = 0.48793(8)Nuclear g-factor:g_l = 0.97586Mirror nucleus:Phosphorus-31Year of discovery:1940

Radioactive Decay

Half-life T_½ = 2.5534(18) s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EE/β⁺	³¹P	100 %	5.39752 MeV

Parent Nuclides

Direct parent isotopes are: ³²Ar, ³¹Cl.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 15) and isobaric (same nucleon number A = 31) with Sulfur-31. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 15	Isobar A = 31
5	²⁰B
6	²¹C
7	²²N
8	²³O
9	²⁴F	³¹F
10	²⁵Ne	³¹Ne
11	²⁶Na	³¹Na
12	²⁷Mg	³¹Mg
13	²⁸Al	³¹Al
14	²⁹Si	³¹Si
15	³⁰P	³¹P
16	³¹S	³¹S
17	³²Cl	³¹Cl
18	³³Ar	³¹Ar
19	³⁴K
20	³⁵Ca
21	³⁶Sc