Krypton-81
Properties and data of the isotope 81Kr.
See also: List of individual Krypton isotopes (and general data sources).
General data
Name of the isotope:Krypton-81; Kr-81Symbol:81Kr or 8136KrMass number A:81 (= number of nucleons)Atomic number Z:36 (= number of protons)Neutrons N:45Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):1.25 (= neutron-proton ratio)Neutron excess (N-Z):9Isotopic mass:80.9165897(12) u (atomic weight of Krypton-81)Nuclide mass:80.8968416 u (calculated nuclear mass without electrons)Mass excess:-77.69619 MeVMass defect:0.755032672 u (per nucleus)Nuclear binding energy:703.30840377 MeV (per nucleus)
8.6828198 MeV (average binding energy per nucleon)Separation energy:SN = 7.8741(12) MeV (first neutron)
SP = 9.0961(15) MeV (first proton)Half-life:2.29(11) × 105 aDecay constant λ:9.598058039165 × 10-14 s-1Specific activity α:722510718.67128 Bq g-1
0.019527316720845 Ci g-1Spin and parity:
(nuclear angular momentum)7/2+Magnetic dipole moment:μ(μN) = - 0.908(2)Quadrupole moment Q:+ 0.586(2) barn (100 fm2)Nuclear g-factor:gl = -0.25942857142857Charge radius:4.1952(26) femtometer fmYear of discovery:1950
Radioactive Decay
Half-life T½ = 2.29(11) × 105 a respectively 7.221744 × 1012 seconds s.
Decay
mode | Daughter | Probability | Decay energy | γ energy
(intensity) |
|---|
| EC | 81Br | 100 % | 0.2809(15) MeV | |
Parent Nuclides
Direct parent isotope is: 81Rb.
Nuclear Isomers
Nuclear isomers or excited states with the activation energy in keV related to the ground state.
| Nuclear Isomer | Excitation Energy | Half-life | Spin |
|---|
| 81mKr | 190.64(4) keV | 13.10(3) s | 1/2- |
Isotones and Isobars
The following table shows the atomic nuclei that are isotonic (same neutron number N = 45) and isobaric (same nucleon number A = 81) with Krypton-81. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
| Z | Isotone N = 45 | Isobar A = 81 |
|---|
| 23 | 68V | |
| 25 | 70Mn | |
| 26 | 71Fe | |
| 27 | 72Co | |
| 28 | 73Ni | |
| 29 | 74Cu | 81Cu |
| 30 | 75Zn | 81Zn |
| 31 | 76Ga | 81Ga |
| 32 | 77Ge | 81Ge |
| 33 | 78As | 81As |
| 34 | 79Se | 81Se |
| 35 | 80Br | 81Br |
| 36 | 81Kr | 81Kr |
| 37 | 82Rb | 81Rb |
| 38 | 83Sr | 81Sr |
| 39 | 84Y | 81Y |
| 40 | 85Zr | 81Zr |
| 41 | 86Nb | 81Nb |
| 42 | 87Mo | 81Mo |
| 43 | 88Tc | |
| 44 | 89Ru | |
| 45 | 90Rh | |
| 46 | 91Pd | |
| 47 | 92Ag | |
External data and identifiers
Last update: 2023-05-22
Perma link: https://www.chemlin.org/isotope/krypton-81
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