Aluminium-31

Properties and data of the isotope ³¹Al.

Content

General data

Name of the isotope:Aluminium-31; Al-31Symbol:³¹Al or 3113AlMass number A:31 (= number of nucleons)Atomic number Z:13 (= number of protons)Neutrons N:18Isotopic mass:30.9839498(24) u (atomic weight of Aluminium-31)Nuclide mass:30.9768183 u (calculated nuclear mass without electrons)Mass excess:-14.95066 MeVMass defect:0.273744104 u (per nucleus)Nuclear binding energy:254.99099041 MeV (per nucleus)
8.22551582 MeV (average binding energy per nucleon)Separation energy:S_N = 7.157(4) MeV (first neutron)
S_P = 13.356(4) MeV (first proton)Half-life:644(25) msDecay constant λ:1.0763154977639 s^-1Specific activity α:2.160574512422 × 10⁺²² Bq g^-1
583939057411.46 Ci g^-1Spin and parity:
(nuclear angular momentum)5/2(+)Magnetic dipole moment:μ(μ_N) = +3.832(5)Quadrupole moment Q:0.1340(16) barn (100 fm²)Nuclear g-factor:g_l = 1.5328Mirror nucleus:Argon-31Year of discovery:1971

Radioactive Decay

Half-life T_½ = 644(25) ms respectively 6.44 × 10^-1 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	³¹Si	98.4 %	7.9983(22) MeV
β^-, n	³⁰Si	1.6 %	1.4109(22) MeV

Parent Nuclides

Direct parent isotope is: ³¹Mg.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 18) and isobaric (same nucleon number A = 31) with Aluminium-31. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 18	Isobar A = 31
7	²⁵N
8	²⁶O
9	²⁷F	³¹F
10	²⁸Ne	³¹Ne
11	²⁹Na	³¹Na
12	³⁰Mg	³¹Mg
13	³¹Al	³¹Al
14	³²Si	³¹Si
15	³³P	³¹P
16	³⁴S	³¹S
17	³⁵Cl	³¹Cl
18	³⁶Ar	³¹Ar
19	³⁷K
20	³⁸Ca
21	³⁹Sc
22	⁴⁰Ti
23	⁴¹V
24	⁴²Cr
25	⁴³Mn