Isotopes of boron

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.

Boron chart
A chart showing the abundances of the naturally occurring isotopes of boron.
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][3]
  • Conventional: 10.81

List of isotopes

Z(p) N(n)  
isotopic mass (u)[4]
[resonance width][5]
decay mode(s)[6] daughter
spin and
(mole fraction)
range of natural
(mole percent)
7B 5 2 7.029712(27) 570(14) × 10−24 s
[801(20) keV]
p 6
[n 1]
8B[n 2] 5 3 8.0246073(11) 770(3) ms β+, α 2 4
9B 5 4 9.0133296(10) 800(300)×10−21 s
[0.54(21) keV]
p, α 2 4
10B 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
β, α (1.6%) 8
[n 3]
13B 5 8 13.0177800(11) 17.33(17) ms β (99.72%) 13
β, n (0.28%) 12
14B 5 9 14.025404(23) 12.5(5) ms β (93.96%) 14
β, n (6.04%) 13
15B 5 10 15.031088(23) 9.93(7) ms β, n (93.6%) 14
β (6.0%) 15
β, 2n (0.4%) 13
16B 5 11 16.039842(26) > 4.6 × 10−21 s
n 15
17B[n 4] 5 12 17.04693(22) 5.08(5) ms β, n (63.0%) 16
β (22.1%) 17
β, 2n (11.0%) 15
β, 3n (3.5%) 14
β, 4n (0.4%) 13
18B 5 13 18.05560(22) < 26 ns n 17
19B[n 4] 5 14 19.06417(56) 2.92(13) ms β, n (71%) 18
β, 2n (17%) 17
β (12%) 19
20B[7] 5 15 20.07348(86)# [2.50(9) MeV] n 19
(1−, 2−)
21B[7] 5 16 21.08302(97)# < 260 ns
[2.47(19) MeV]
2n 19
  1. ^ Subsequently decays by double proton emission to 4He for a net reaction of 7B → 4He + 3 1H
  2. ^ Has 1 halo proton
  3. ^ Immediately decays into two α particles, for a net reaction of 12B → 3 4He + e
  4. ^ a b Has 2 halo neutrons


  • The precision of the isotope abundances and atomic mass is limited through variations. The given ranges should be applicable to any normal terrestrial material.
  • Commercially available materials may have been subjected to an undisclosed or inadvertent isotopic fractionation. Substantial deviations from the given mass and composition can occur.
  • Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
  • Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC, which use folical uncertainties.[8]
  • Nuclide masses are given by IUPAP Commission on Symbols, Units, Nomenclature, Atomic Masses and Fundamental Constants (SUNAMCO).
  • Isotope abundances are given by IUPAC Commission on Isotopic Abundances and Atomic Weights (CIAAW).
  • Neutrinos from boron-8 beta decays within the sun are an important background to dark matter direct detection experiments.[9] They are the first component of the neutrino floor that dark matter direct detection experiments are expected to eventually encounter.



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



  1. ^ 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. ^ Meija, J.; et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry. 88 (3): 265–91. doi:10.1515/pac-2015-0305.
  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—030001–442, doi:10.1088/1674-1137/41/3/030003
  5. ^ 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): 030001–1—030001–138, Bibcode:2017ChPhC..41c0001A, doi:10.1088/1674-1137/41/3/030001
  6. ^ "Universal Nuclide Chart". nucleonica. (Registration required (help)).
  7. ^ 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.
  8. ^ "2.5.7. Standard and expanded uncertainties". Engineering Statistics Handbook. Retrieved 2010-09-16.
  9. ^ 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.

General references


Boron is a chemical element with symbol B and atomic number 5. Produced entirely by cosmic ray spallation and supernovae and not by stellar nucleosynthesis, it is a low-abundance element in the Solar system and in the Earth's crust. Boron is concentrated on Earth by the water-solubility of its more common naturally occurring compounds, the borate minerals. These are mined industrially as evaporites, such as borax and kernite. The largest known boron deposits are in Turkey, the largest producer of boron minerals.

Elemental boron is a metalloid that is found in small amounts in meteoroids but chemically uncombined boron is not otherwise found naturally on Earth. Industrially, very pure boron is produced with difficulty because of refractory contamination by carbon or other elements. Several allotropes of boron exist: amorphous boron is a brown powder; crystalline boron is silvery to black, extremely hard (about 9.5 on the Mohs scale), and a poor electrical conductor at room temperature. The primary use of elemental boron is as boron filaments with applications similar to carbon fibers in some high-strength materials.

Boron is primarily used in chemical compounds. About half of all boron consumed globally is an additive in fiberglass for insulation and structural materials. The next leading use is in polymers and ceramics in high-strength, lightweight structural and refractory materials. Borosilicate glass is desired for its greater strength and thermal shock resistance than ordinary soda lime glass. Boron as sodium perborate is used as a bleach. A small amount of boron is used as a dopant in semiconductors, and reagent intermediates in the synthesis of organic fine chemicals. A few boron-containing organic pharmaceuticals are used or are in study. Natural boron is composed of two stable isotopes, one of which (boron-10) has a number of uses as a neutron-capturing agent.

In biology, borates have low toxicity in mammals (similar to table salt), but are more toxic to arthropods and are used as insecticides. Boric acid is mildly antimicrobial, and several natural boron-containing organic antibiotics are known. Boron is an essential plant nutrient and boron compounds such as borax and boric acid are used as fertilizers in agriculture, although it's only required in small amounts, with excess being toxic. Boron compounds play a strengthening role in the cell walls of all plants. There is no consensus on whether boron is an essential nutrient for mammals, including humans, although there is some evidence it supports bone health.

Boron (disambiguation)

Boron is a chemical element with symbol B and atomic number 5.

Boron may also refer to:

Boron (surname)

Boron, California, a census-designated place in the United States

Boron Air Force Station

Boron, Ivory Coast, a town

Boron, Mali, a town and commune

Boron, Territoire de Belfort, a commune département in France

Boron Oil, a subsidiary and brand of Standard Oil of Ohio, acquired by BP

Bodhu Boron, an Indian wedding ritual

Boron, a fictional character in the House of Bëor in J. R. R. Tolkien's Middle-earth legendarium

Isotopes of boron

Period 2 element

A period 2 element is one of the chemical elements in the second row (or period) of the periodic table of the chemical elements. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behavior of the elements as their atomic number increases; a new row is started when chemical behavior begins to repeat, creating columns of elements with similar properties.

The second period contains the elements lithium, beryllium, boron, carbon, nitrogen, oxygen, fluorine, and neon. This situation can be explained by modern theories of atomic structure. In a quantum mechanical description of atomic structure, this period corresponds to the filling of the 2s and 2p orbitals. Period 2 elements obey the octet rule in that they need eight electrons to complete their valence shell. The maximum number of electrons that these elements can accommodate is ten, two in the 1s orbital, two in the 2s orbital and six in the 2p orbital.

Samuel King Allison

Samuel King Allison (November 13, 1900 – September 15, 1965) was an American physicist, most notable for his role in the Manhattan Project, for which he was awarded the Medal for Merit. He was director of the Metallurgical Laboratory from 1943 until 1944, and later worked at the Los Alamos Laboratory — where he "rode herd" on the final stages of the project as part of the "Cowpuncher Committee", and read the countdown for the detonation of the Trinity nuclear test. After the war, he returned to the University of Chicago to direct the Institute for Nuclear Studies and was involved in the "scientists' movement", lobbying for civilian control of nuclear weapons.

Uranium borohydride

Uranium borohydride is the inorganic compound with the empirical formula U(BH4)4. Two polymeric forms are known, as well as a monomeric derivative that exists in the gas phase. Because the polymers convert to the gaseous form at mild temperatures, uranium borohydride once attracted much attention. It is solid green.

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