Strontium-81

Properties and data of the isotope ⁸¹Sr.

Contents

General data

Name of the isotope:Strontium-81; Sr-81Symbol:⁸¹Sr or 8138SrMass number A:81 (= number of nucleons)Atomic number Z:38 (= number of protons)Neutrons N:43Isotopic mass:80.923211(3) u (atomic weight of Strontium-81)Nuclide mass:80.9023658 u (calculated nuclear mass without electrons)Mass excess:-71.52849 MeVMass defect:0.746731604 u (per nucleus)Nuclear binding energy:695.57600874 MeV (per nucleus)
8.58735813 MeV (average binding energy per nucleon)Separation energy:S_N = 9.288(5) MeV (first neutron)
S_P = 6.642(4) MeV (first proton)Half-life:22.3(4) minDecay constant λ:0.00051804722014944 s^-1Specific activity α:3.899691664798 × 10⁺¹⁸ Bq g^-1
105397072.02157 Ci g^-1Spin and parity:
(nuclear angular momentum)1/2-Magnetic dipole moment:μ(μ_N) = +0.543(4)Nuclear g-factor:g_l = 1.086Charge radius:4.2547(34) femtometer fmYear of discovery:1952

Radioactive Decay

Half-life T_½ = 22.3(4) min (minutes) respectively 1.338 × 10³ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EC/β⁺	⁸¹Rb	100 %	3.929(6) MeV

Parent Nuclides

Direct parent isotope is: ⁸¹Y.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 43) and isobaric (same nucleon number A = 81) with Strontium-81. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 43	Isobar A = 81
23	⁶⁶V
24	⁶⁷Cr
25	⁶⁸Mn
26	⁶⁹Fe
27	⁷⁰Co
28	⁷¹Ni
29	⁷²Cu	⁸¹Cu
30	⁷³Zn	⁸¹Zn
31	⁷⁴Ga	⁸¹Ga
32	⁷⁵Ge	⁸¹Ge
33	⁷⁶As	⁸¹As
34	⁷⁷Se	⁸¹Se
35	⁷⁸Br	⁸¹Br
36	⁷⁹Kr	⁸¹Kr
37	⁸⁰Rb	⁸¹Rb
38	⁸¹Sr	⁸¹Sr
39	⁸²Y	⁸¹Y
40	⁸³Zr	⁸¹Zr
41	⁸⁴Nb	⁸¹Nb
42	⁸⁵Mo	⁸¹Mo
43	⁸⁶Tc
44	⁸⁷Ru