There are 14 known isotopes of the chemical element boron, of which the nuclides 10B and 11B are stable.< /p>
The atomic mass of boron is given as an average of 10.81 u, or with an interval of 10.806 to 10.821 u.
Boron occurs in nature in an average ratio of about 20 to 80:
| Atomic Mass ma | Quantity | Half-life | Spin | |
| Boron Isotopic mixture | 10,81 u | 100 % | ||
| Isotope 10B | 10,012937(3) u | 19,65 % | stable | 3+ |
| Isotope 11B | 11,009305(3) u | 80,35 % | stable | 3/2- |
Bor-10 is a neutron scavenger with a neutron capture cross-section that is 8 x 105 higher than that of boron-11: After neutron capture, the 10B(n,α ) to 7Li and 4He and thus binds the neutron, which is then no longer available in a chain reaction in nuclear reactors, for example (moderator).
The so-called 10boron neutron capture therapy (BNCT) against cancer works according to the same principle: After the application of certain boron compounds into a tumor, it is irradiated with thermal neutrons. The released Li and He nuclei have a range of only a few micrometers and destroy the surrounding tumor tissue.
| Isotope Nuclide | E | N | Atomic Mass [Nuclear Mass] {Mass Excess} | Spin I (h/2π) | Parent |
|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 5 | 6 |
| Boron-6 | 65B | 1 | 6.05080(215) u [6.0480571 u] {47.3199 MeV} | (2-) | |
| Boron-7 | 75B | 2 | 7.029712(27) u [7.0269691 u] {27.67655 MeV} | (3/2-) | |
| Boron-8 | 85B | 3 | 8.0246073(11) u [8.0218644 u] {22.92155 MeV} | 2+ | |
| Boron-9 | 95B | 4 | 9.0133296(10) u [9.0105867 u] {12.41644 MeV} | 3/2- | 9C |
| Boron-10 | 105B | 5 | 10.012937(3) u [10.0101941 u] {12.05074 MeV} | 3+ | 10Be 10C |
| Boron-11 | 115B | 6 | 11.009305(3) u [11.0065621 u] {8.66755 MeV} | 3/2- | 11Be 11C |
| Boron-12 | 125B | 7 | 12.0143526(14) u [12.0116097 u] {13.36936 MeV} | 1+ | 12Be |
| Boron-13 | 135B | 8 | 13.0177800(11) u [13.0150371 u] {16.56196 MeV} | 3/2- | |
| Boron-14 | 145B | 9 | 14.025404(23) u [14.0226611 u] {23.66367 MeV} | 2- | |
| Boron-15 | 155B | 10 | 15.031087(23) u [15.0283441 u] {28.95735 MeV} | 3/2- | |
| Boron-16 | 165B | 11 | 16.039841(26) u [16.0370981 u] {37.11165 MeV} | 0- | |
| Boron-17 | 175B | 12 | 17.04693(22) u [17.0441871 u] {43.71501 MeV} | (3/2-) | |
| Boron-18 | 185B | 13 | 18.05560(22) u [18.0528571 u] {51.79107 MeV} | (2-) | |
| Boron-19 | 195B | 14 | 19.06417(56) u [19.0614271 u] {59.77397 MeV} | 3/2- | |
| Boron-20 | 205B | 15 | 20.07451(59) u [20.0717671 u] {69.40562 MeV} | (1-, 2-) | |
| Boron-21 | 215B | 16 | 21.08415(60) u [21.0814071 u] {78.38522 MeV} | (3/2-) |
| Isotope | Radioactive Decay | Extern | |||
|---|---|---|---|---|---|
| Half-life | Decay Mode | Probability | Energy | ||
| 7 | 8 | 9 | 10 | 11 | 12 |
| B-6 | 2p ? → 6Li | AL | |||
| B-7 | 570(14) × 10-24 s | p → 6Be | 11.9 MeV | AL | |
| B-8 | 771.17(94) ms | EC β+ → 8Be β+, α 4He | 100 % | 17.9798(10) MeV | AL |
| B-9 | 800(300) zs | p → 8Be | 100 % | AL | |
| B-10 | stable | AL | |||
| B-11 | stable | AL | |||
| B-12 | 20.20(2) ms | β- → 12C β-, α → 8Be | 99.40(2) % 0.60(2) % | 13.3694(13) MeV | AL |
| B-13 | 17.16(18) ms | β- → 13C β-, n → 12C | 99.734(36) % 0.266(36) % | 13.4369(10) MeV | AL |
| B-14 | 12.36(29) ms | β- → 14C β-, n → 13C β-, 2n → 12C | 93.96(23) % 6.04(23) % ? | 20.644(21) MeV | AL |
| B-15 | 10.18(35) ms | β- → 15C β-, n → 14C β-, 2n → 13C | < 1.3 % 98.7(10) % < 1.5 % | 19.085(21) MeV | AL |
| B-16 | > 4.6 × 10-21 s | n 15B | 100 % | AL | |
| B-17 | 5.08(5) ms | β- → 17C β-, n → 16C β-, 2n → 15C β-, 3n → 14C β-, 4n → 13C | 22.1 % 63.0 % 11.0 % 3.5 % 0.40 % | AL | |
| B-18 | < 26 ns | n → 17B | AL | ||
| B-19 | 2.92(13) ms | β-, n → 18C β-, 2n → 17C β- → 19C β-, 3n → 16C | 71 % 17 % > 2.9 % < 9.1 % | AL | |
| B-20 | < 260 ns | n → 19B | AL | ||
| B-21 | < 260 ns | 2n → 19B | AL | ||
Notes (related to the columns):
1 - name of the nuclide, isotope.
2 - E: isotope symbol with mass number (superscript; number of nucleons) and Atomic number (subscript; number of protons).
3 - N: number of neutrons.
4 - relative atomic mass of the Boron isotope (isotopic mass including electrons) and the mass of the atomic nucleus in square brackets (nuclear mass, nuclide mass without electrons), each related to 12C = 12.00000 [2]. In addition, the mass excess is given in MeV.
5 - nuclear spin I, unit: h/2π.
6 - source nuclides: Possible, assumed or actual source nuclides (mother nuclides, parent nuclides). If applicable, the corresponding decay modes can be found in the data for the respective starting nuclide.
7 - isotope notation in short form.
8 - decay: half-live of the Boron isotope (a = years; ; d = days; h = hours; min = minutes; s = seconds).
9 - decay mode: type of decay into the respective daughter nuclides with n = neutron emission; p = proton emission; α = alpha decay; β- = beta minus decay with electron emission; EC = electron capture; β+ = positron emission; ε = β+ and/or EC; Iso = isomeric transition; CD = cluster decay; SF = spontaneous decay.
10 - decay probability in percent (%).
11 - decay energy; Particle energy related to decay type.
12 - other information and notes: AL = Adopted Levels (link to external data [1]).
Miscellaneous:
()- Numbers in brackets: uncertainty to represent the spread of the reported value.
~ - Theoretical values or systematic trends.
- unlisted-: Nuclides that have already been mentioned in the literature but for some reason can no longer be found in the current nuclide tables because their discovery e.g. has not confirmed.
| Nuclide quantity 1) spin | Nuclear magnetic moment μ/μN | Gyromagnetic ratio {Quadrupole moment} | Resonant frequency v0 bei 1 T | Relative sensitivity H0 = const. v0 = const. 3) |
|---|---|---|---|---|
| 10B 19,65 % 3+ | 1,8004636(8) | 2,875 {+0,0846(2)} | 4,5752 | 0,01985 1,7193 |
| 11B 80,35 % 3/2- | 2,688378(1) | 8,584 {0,04059(10)} | 13,6630 | 0,16522 1,6045 |
1) Quantity Percentage of natural occurrence.
2) Gyromagnetic ratio: 107 rad T-1 s-1
Quadrupole moment: Q [barn] = [100 fm2]
3) Related to 1H = 1,000.
Properties of the Boron nucleides
[1] - NuDat: National Nuclear Data Center, Brookhaven National Laboratory, based on ENSDF and the Nuclear Wallet Cards.
[2] - G. Audi et. al.: The NUBASE evaluation of nuclear and decay properties. Nuclear Physics, (2003), DOI 10.1016/j.nuclphysa.2003.11.001.
[3] - Live Chart of Nuclides. Nuclear structure and decay data.
Boron: NMR properties - 10B-NMR, 11B-NMR
[4] - N. J. Stone: Table of nuclear magnetic dipole and electric quadrupole moments. Atomic Data and Nuclear Data Tables, (2005), DOI 10.1016/j.adt.2005.04.001.
[5] - Pekka Pyykkö: Year-2008 nuclear quadrupole moments. Molecular Physics, (2008), DOI 10.1080/00268970802018367.
[6] - Pekka Pyykkö: Year-2017 nuclear quadrupole moments. Molecular Physics, (2018), DOI 10.1080/00268976.2018.1426131.
[7] - N. J. Stone: Table of recommended nuclear magnetic dipole moments. IAEA, (2019).
More sources:
[8] - Isotopic abundances, atomic weights and isotopic masses: see respective keyword.
Last update: 2022-12-12
Perma link: https://www.chemlin.org/chemical-elements/boron-isotopes.php
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