Arsenic-81

Properties and data of the isotope ⁸¹As.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

See also: List of individual Arsenic isotopes (and general data sources).

General data

Name of the isotope:Arsenic-81; As-81Symbol:⁸¹As or 8133AsMass number A:81 (= number of nucleons)Atomic number Z:33 (= number of protons)Neutrons N:48Isotopic mass:80.9221323(28) u (atomic weight of Arsenic-81)Nuclide mass:80.9040298 u (calculated nuclear mass without electrons)Mass excess:-72.5333 MeVMass defect:0.752009724 u (per nucleus)Nuclear binding energy:700.49254585 MeV (per nucleus)
8.64805612 MeV (average binding energy per nucleon)Separation energy:S_N = 8.390(4) MeV (first neutron)
S_P = 10.287(3) MeV (first proton)Half-life:33.3(8) sDecay constant λ:0.020815230647446 s^-1Specific activity α:1.566903137387 × 10⁺²⁰ Bq g^-1
4234873344.2903 Ci g^-1Spin and parity:
(nuclear angular momentum)3/2-Year of discovery:1960

Radioactive Decay

Half-life T_½ = 33.3(8) s respectively 3.33 × 10¹ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	⁸¹Se	100 %	3.8557(28) MeV

Parent Nuclides

Direct parent isotope is: ⁸¹Ge.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 48) and isobaric (same nucleon number A = 81) with Arsenic-81. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 48	Isobar A = 81
26	⁷⁴Fe
27	⁷⁵Co
28	⁷⁶Ni
29	⁷⁷Cu	⁸¹Cu
30	⁷⁸Zn	⁸¹Zn
31	⁷⁹Ga	⁸¹Ga
32	⁸⁰Ge	⁸¹Ge
33	⁸¹As	⁸¹As
34	⁸²Se	⁸¹Se
35	⁸³Br	⁸¹Br
36	⁸⁴Kr	⁸¹Kr
37	⁸⁵Rb	⁸¹Rb
38	⁸⁶Sr	⁸¹Sr
39	⁸⁷Y	⁸¹Y
40	⁸⁸Zr	⁸¹Zr
41	⁸⁹Nb	⁸¹Nb
42	⁹⁰Mo	⁸¹Mo
43	⁹¹Tc
44	⁹²Ru
45	⁹³Rh
46	⁹⁴Pd
47	⁹⁵Ag
48	⁹⁶Cd
49	⁹⁷In
50	⁹⁸Sn