Yttrium-81

Properties and data of the isotope ⁸¹Y.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

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

General data

Name of the isotope:Yttrium-81; Y-81Symbol:⁸¹Y or 8139YMass number A:81 (= number of nucleons)Atomic number Z:39 (= number of protons)Neutrons N:42Nucleon pairing (Z - N):odd - evenNuclear ratio (N/Z ratio):1.0769230769231 (= neutron-proton ratio)Neutron excess (N-Z):3Isotopic mass:80.929454(6) u (atomic weight of Yttrium-81)Nuclide mass:80.9080603 u (calculated nuclear mass without electrons)Mass excess:-65.71318 MeVMass defect:0.73964871999999 u (per nucleus)Nuclear binding energy:688.97834479 MeV (per nucleus)
8.50590549 MeV (average binding energy per nucleon)Separation energy:S_N = 12.636(8) MeV (first neutron)
S_P = 2.69(6) MeV (first proton)Half-life:70.4(10) sDecay constant λ:0.0098458406329538 s^-1Specific activity α:7.41162989701 × 10⁺¹⁹ Bq g^-1
2003143215.41 Ci g^-1Spin and parity:
(nuclear angular momentum)(5/2+)Mirror nucleus:Molybdenum-81Year of discovery:1981

Radioactive Decay

Half-life T_½ = 70.4(10) s respectively 7.04 × 10¹ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EC/β⁺	⁸¹Sr	100 %	5.815(6) MeV

Parent Nuclides

Direct parent isotope is: ⁸¹Zr.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 42) and isobaric (same nucleon number A = 81) with Yttrium-81. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 42	Isobar A = 81
21	⁶³Sc
22	⁶⁴Ti
23	⁶⁵V
24	⁶⁶Cr
25	⁶⁷Mn
26	⁶⁸Fe
27	⁶⁹Co
28	⁷⁰Ni
29	⁷¹Cu	⁸¹Cu
30	⁷²Zn	⁸¹Zn
31	⁷³Ga	⁸¹Ga
32	⁷⁴Ge	⁸¹Ge
33	⁷⁵As	⁸¹As
34	⁷⁶Se	⁸¹Se
35	⁷⁷Br	⁸¹Br
36	⁷⁸Kr	⁸¹Kr
37	⁷⁹Rb	⁸¹Rb
38	⁸⁰Sr	⁸¹Sr
39	⁸¹Y	⁸¹Y
40	⁸²Zr	⁸¹Zr
41	⁸³Nb	⁸¹Nb
42	⁸⁴Mo	⁸¹Mo
43	⁸⁵Tc
44	⁸⁶Ru