Argon-31
Properties and data of the isotope 31Ar.
See also: list of Argon isotopes.
General data
Name of the isotope:Argon-31; Ar-31Symbol:31Ar or 3118ArMass number A:31 (= number of nucleons)Atomic number Z:18 (= number of protons)Neutrons N:13Isotopic mass:31.01216(22) u (atomic weight of Argon-31)Nuclide mass:31.0022857 u (calculated nuclear mass without electrons)Mass excess:11.32697 MeVMass defect:0.241334484 u (per nucleus)Nuclear binding energy:224.80162384 MeV (per nucleus)
7.25166529 MeV (average binding energy per nucleon)Separation energy:SN = 17.68(29) MeV (first neutron)
SP = 0.41(28) MeV (first proton)Half-life:14.4(6) msDecay constant λ:48.135220872218 s-1Specific activity α:9.35087356182 × 10+23 Bq g-1
25272631248184 Ci g-1Spin and parity:
(nuclear angular momentum)5/2+Mirror nucleus:Aluminium-31Year of discovery:1986
Radioactive Decay
Half-life T½ = 14.4(6) ms respectively 1.44 × 10-2 seconds s.
Decay mode | Daughter | Probability | Decay energy | γ energy (intensity) |
---|
EC/β+ | 31Cl | | 18.36(20) MeV | |
β+, p | 30S | 63(7) % | | |
β+, 2p | 29P | 7.2(11) % | | |
β+, 3p | 28Si | 2.1(10) % | | |
Isotones and Isobars
The following table shows the atomic nuclei that are isotonic (same neutron number N = 13) and isobaric (same nucleon number A = 31) with Argon-31. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
Z | Isotone N = 13 | Isobar A = 31 |
5 | 18B | |
6 | 19C | |
7 | 20N | |
8 | 21O | |
9 | 22F | 31F |
10 | 23Ne | 31Ne |
11 | 24Na | 31Na |
12 | 25Mg | 31Mg |
13 | 26Al | 31Al |
14 | 27Si | 31Si |
15 | 28P | 31P |
16 | 29S | 31S |
17 | 30Cl | 31Cl |
18 | 31Ar | 31Ar |
19 | 32K | |
External data and identifiers
Last update: 2023-10-04
Perma link: https://www.chemlin.org/isotope/argon-31
© 1996 - 2025 ChemLin