Isotopes of boron

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Main isotopes of boron (5B)
Iso­tope Decay
abun­dance half-life (t1/2) mode pro­duct
10B 20% stable[1]
11B 80% stable[1]
10B content may be as low as 19.1% and as high as 20.3% in natural samples. 11B is the remainder in such cases.[2]
Standard atomic weight Ar, standard(B)[10.806, 10.821] conventional: 10.81
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Boron (5B) naturally occurs as isotopes 10B and 11B, the latter of which makes up about 80% of natural boron. There are 13 radioisotopes that have been discovered, with mass numbers from 7 to 21, all with short half-lives, the longest being that of 8B, with a half-life of only 770 milliseconds (ms) and 12B with a half-life of 20.2 ms. All other isotopes have half-lives shorter than 17.35 ms. Those isotopes with mass below 10 decay into helium (via short-lived isotopes of beryllium for 7B and 9B) while those with mass above 11 mostly become carbon.

A chart showing the abundances of the naturally occurring isotopes of boron.

List of isotopes[]

Nuclide[3]
[n 1] 		Z N Isotopic mass (Da)[4]
[n 2][n 3] 		Half-life

[resonance width] 		Decay
mode
[n 4] 		Daughter
isotope
[n 5] 		Spin and
parity
[n 6][n 7] 		Natural abundance (mole fraction)
Excitation energy Normal proportion Range of variation
7B 5  2 7.029712(27) 570(14) × 10−24 s
[801(20) keV] 		p 6
Be
[n 8] 		(3/2−)
8B[n 9] 5  3 8.0246073(11) 770(3) ms β+, α 2 4
He
 		2+
9B 5  4 9.0133296(10) 800(300) × 10−21 s
[0.54(21) keV] 		p, α 2 4
He
 		3/2−
10B[n 10] 5  5 10.012936862(16) Stable 3+ 0.199(7) 18.929–20.386
11B 5  6 11.009305167(13) Stable 3/2− 0.801(7) 79.614–81.071
12B 5  7 12.0143526(14) 20.20(2) ms β− (98.4%) 12
C
 		1+
β−, α (1.6%) 8
Be
[n 11]
13B 5  8 13.0177800(11) 17.33(17) ms β− (99.72%) 13
C
 		3/2−
β−, n (0.28%) 12
C
14B 5  9 14.025404(23) 12.5(5) ms β− (93.96%) 14
C
 		2−
β−, n (6.04%) 13
C
15B 5 10 15.031088(23) 9.93(7) ms β−, n (93.6%) 14
C
 		3/2−
β− (6.0%) 15
C
β−, 2n (0.4%) 13
C
16B 5 11 16.039842(26) > 4.6 × 10−21 s
 n 15
B
 		0−
17B[n 12] 5 12 17.04693(22) 5.08(5) ms β−, n (63.0%) 16
C
 		(3/2−)
β− (22.1%) 17
C
β−, 2n (11.0%) 15
C
β−, 3n (3.5%) 14
C
β−, 4n (0.4%) 13
C
18B 5 13 18.05560(22) < 26 ns n 17
B
 		(2−)
19B[n 12] 5 14 19.06417(56) 2.92(13) ms β−, n (71%) 18
C
 		3/2−#
β−, 2n (17%) 17
C
β− (12%) 19
C
20B[5] 5 15 20.07348(86)# [2.50(9) MeV] n 19
B
 		(1−, 2−)
21B[5] 5 16 21.08302(97)# < 260 ns
[2.47(19) MeV] 		2n 19
B
 		(3/2−)#
This table header & footer:
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  1. ^ mB – Excited nuclear isomer.
  2. ^ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
  3. ^ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
  4. ^ Modes of decay:
    n: Neutron emission
    p: Proton emission
  5. ^ Bold symbol as daughter – Daughter product is stable.
  6. ^ ( ) spin value – Indicates spin with weak assignment arguments.
  7. ^ # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  8. ^ Subsequently decays by double proton emission to 4He for a net reaction of 7B → 4He + 3 1H
  9. ^ Has 1 halo proton
  10. ^ One of the few stable odd-odd nuclei
  11. ^ Immediately decays into two α particles, for a net reaction of 12B → 3 4He +  e−
  12. ^ Jump up to: a b Has 2 halo neutrons
  • Neutrinos from boron-8 beta decays within the sun are an important background to dark matter direct detection experiments.[6] They are the first component of the neutrino floor that dark matter direct detection experiments are expected to eventually encounter.

Applications[]

Boron-10[]

Boron-10 is used in boron neutron capture therapy as an experimental treatment of some brain cancers.

References[]

  1. ^ Jump up to: a b "Atomic Weights and Isotopic Compositions for All Elements". National Institute of Standards and Technology. Retrieved 2008-09-21.
  2. ^ Szegedi, S.; Váradi, M.; Buczkó, Cs. M.; Várnagy, M.; Sztaricskai, T. (1990). "Determination of boron in glass by neutron transmission method". Journal of Radioanalytical and Nuclear Chemistry Letters. 146 (3): 177. doi:10.1007/BF02165219.
  3. ^ Half-life, decay mode, nuclear spin, and isotopic composition is sourced in:
    Audi, G.; Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S. (2017). "The NUBASE2016 evaluation of nuclear properties" (PDF). Chinese Physics C. 41 (3): 030001. Bibcode:2017ChPhC..41c0001A. doi:10.1088/1674-1137/41/3/030001.
  4. ^ Wang, M.; Audi, G.; Kondev, F. G.; Huang, W. J.; Naimi, S.; Xu, X. (2017). "The AME2016 atomic mass evaluation (II). Tables, graphs, and references" (PDF). Chinese Physics C. 41 (3): 030003-1–030003-442. doi:10.1088/1674-1137/41/3/030003.
  5. ^ Jump up to: a b Leblond, S.; et al. (2018). "First observation of 20B and 21B". Physical Review Letters. 121 (26): 262502–1–262502–6. arXiv:1901.00455. doi:10.1103/PhysRevLett.121.262502. PMID 30636115.
  6. ^ Cerdeno, David G.; Fairbairn, Malcolm; Jubb, Thomas; Machado, Pedro; Vincent, Aaron C.; Boehm, Celine (2016). "Physics from solar neutrinos in dark matter direct detection experiments". JHEP. 2016 (5): 118. arXiv:1604.01025. Bibcode:2016JHEP...05..118C. doi:10.1007/JHEP05(2016)118.
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