Bromine-81
Properties and data of the isotope 81Br.
See also: list of Bromine isotopes.
General data
Name of the isotope:Bromine-81; Br-81Symbol:81Br or 8135BrMass number A:81 (= number of nucleons)Atomic number Z:35 (= number of protons)Neutrons N:46Isotopic mass:80.91690(9) u (atomic weight of Bromine-81)Nuclide mass:80.8977004 u (calculated nuclear mass without electrons)Mass excess:-77.40715 MeVMass defect:0.755562256 u (per nucleus)Nuclear binding energy:703.80170809 MeV (per nucleus)
8.68890998 MeV (average binding energy per nucleon)Separation energy:SN = 10.1594(14) MeV (first neutron)
SP = 7.5065(14) MeV (first proton)Half-life:stableSpin and parity:
(nuclear angular momentum)3/2-Magnetic dipole moment:μ(μN) = +2.2686(6)Charge radius:4.1599(21) femtometer fmYear of discovery:1920
Parent Nuclides
Direct parent isotopes are: 81Kr, 81Se.
Occurrence
Comparison of the natural Bromine isotopes including isotopic abundance (mole fraction of the isotope mixture in percent):
| | Atomic Mass ma | Quantity | Half-life | Spin |
|---|
Bromine
Isotopic mixture | 79.904 u | 100 % | | |
| Isotope 79Br | 78.918338(9) u | 50.65 %
[50.5 - 50.8 %] | stable | 3/2- |
| Isotope 81Br | 80.91690(9) u | 49.35 %
[49.2 - 49.5 %] | stable | 3/2- |
NMR data
Nuclear magnetic properties of the NMR active Nuclide 81Br
Isotope:81Br-NMRQuantity:49.35 % [49.2 - 49.5 %]Spin:3/2-Nuclearmagnetic moment
μ/μN:+2.2686(6)Gyromagnetic ratio γ:7.2498 · 107 rad T-1 s-1Nuclear g-factor:gl = 1.5124Quadrupole moment Q:+ 0.2579(2) barn (100 fm2)Resonance frequency:v0 = 11.5384 at 1 TRelative Sensitivity:0.09951 (H0 = const.)
1.3550 (v0 = const.)
[related to 1H = 1.000]
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 |
|---|
| 81mBr | 536.20(9) keV | 34.6(28) μs | 9/2+ |
Isotones and Isobars
The following table shows the atomic nuclei that are isotonic (same neutron number N = 46) and isobaric (same nucleon number A = 81) with Bromine-81. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
| Z | Isotone N = 46 | Isobar A = 81 |
|---|
| 25 | 71Mn | |
| 26 | 72Fe | |
| 27 | 73Co | |
| 28 | 74Ni | |
| 29 | 75Cu | 81Cu |
| 30 | 76Zn | 81Zn |
| 31 | 77Ga | 81Ga |
| 32 | 78Ge | 81Ge |
| 33 | 79As | 81As |
| 34 | 80Se | 81Se |
| 35 | 81Br | 81Br |
| 36 | 82Kr | 81Kr |
| 37 | 83Rb | 81Rb |
| 38 | 84Sr | 81Sr |
| 39 | 85Y | 81Y |
| 40 | 86Zr | 81Zr |
| 41 | 87Nb | 81Nb |
| 42 | 88Mo | 81Mo |
| 43 | 89Tc | |
| 44 | 90Ru | |
| 45 | 91Rh | |
| 46 | 92Pd | |
| 47 | 93Ag | |
| 48 | 94Cd | |
External data and identifiers
Last update: 2020-10-14
Perma link: https://www.chemlin.org/isotope/bromine-81
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