Arsenic-78

Properties and data of the isotope ⁷⁸As.

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-78; As-78Symbol:⁷⁸As or 7833AsMass number A:78 (= number of nucleons)Atomic number Z:33 (= number of protons)Neutrons N:45Nucleon pairing (Z - N):odd - oddNuclear ratio (N/Z ratio):1.3636363636364 (= neutron-proton ratio)Neutron excess (N-Z):12Isotopic mass:77.921828(10) u (atomic weight of Arsenic-78)Nuclide mass:77.9037255 u (calculated nuclear mass without electrons)Mass excess:-72.81675 MeVMass defect:0.726319276 u (per nucleus)Nuclear binding energy:676.56204768 MeV (per nucleus)
8.67387241 MeV (average binding energy per nucleon)Separation energy:S_N = 6.972(10) MeV (first neutron)
S_P = 8.893(10) MeV (first proton)Half-life:90.7(2) minDecay constant λ:0.00012736993395074 s^-1Specific activity α:9.961554332106 × 10⁺¹⁷ Bq g^-1
26923119.816505 Ci g^-1Spin and parity:
(nuclear angular momentum)2-Year of discovery:1937

Radioactive Decay

Half-life T_½ = 90.7(2) min (minutes) respectively 5.442 × 10³ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	⁷⁸Se	100 %	4.209(10) MeV

Parent Nuclides

Direct parent isotope is: ⁷⁸Ge.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 45) and isobaric (same nucleon number A = 78) with Arsenic-78. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 45	Isobar A = 78
23	⁶⁸V
25	⁷⁰Mn
26	⁷¹Fe
27	⁷²Co
28	⁷³Ni	⁷⁸Ni
29	⁷⁴Cu	⁷⁸Cu
30	⁷⁵Zn	⁷⁸Zn
31	⁷⁶Ga	⁷⁸Ga
32	⁷⁷Ge	⁷⁸Ge
33	⁷⁸As	⁷⁸As
34	⁷⁹Se	⁷⁸Se
35	⁸⁰Br	⁷⁸Br
36	⁸¹Kr	⁷⁸Kr
37	⁸²Rb	⁷⁸Rb
38	⁸³Sr	⁷⁸Sr
39	⁸⁴Y	⁷⁸Y
40	⁸⁵Zr	⁷⁸Zr
41	⁸⁶Nb
42	⁸⁷Mo
43	⁸⁸Tc
44	⁸⁹Ru
45	⁹⁰Rh
46	⁹¹Pd
47	⁹²Ag