Boron-17

Properties and data of the isotope ¹⁷B.

Contents

Boron-17 is a radioisotope of the chemical element boron, which has 12 neutrons in its atomic nucleus in addition to the element-specific 5 protons; the sum of the number of these atomic nucleus building blocks results in a mass number of 17. The very short-lived, only artificially produced, unstable and thus radioactive nuclide has no practical significance; the study of ¹⁷B is exclusively for academic purposes.

The discovery of the neutron-rich nuclide was reported in 1973 [1]; B-17 was observed as a fragment when uranium was bombarded with 4.8 GeV protons.

General data

Name of the isotope:Boron-17; B-17Symbol:¹⁷B or 175BMass number A:17 (= number of nucleons)Atomic number Z:5 (= number of protons)Neutrons N:12Isotopic mass:17.04693(22) u (atomic weight of Boron-17)Nuclide mass:17.0441871 u (calculated nuclear mass without electrons)Mass excess:43.71501 MeVMass defect:0.096174152 u (per nucleus)Nuclear binding energy:89.58564554 MeV (per nucleus)
5.26974386 MeV (average binding energy per nucleon)Separation energy:S_N = 1.467(206) MeV (first neutron)
S_P = 21.020(263) MeV (first proton)Half-life:5.08(5) msDecay constant λ:136.44629538582 s^-1Specific activity α:4.833522415470 × 10⁺²⁴ Bq g^-1
1.306357409586 × 10⁺¹⁴ Ci g^-1Spin and parity:
(nuclear angular momentum)(3/2-)Magnetic dipole moment:μ(μ_N) = +2.55(2)Quadrupole moment Q:0.0385(15) barn (100 fm²)Nuclear g-factor:g_l = 1.7Year of discovery:1973

Radioactive Decay

Half-life T_½ = 5.08(5) ms respectively 5.08 × 10^-3 seconds s.

Decay mode	Daughter	Probability
β^-	¹⁷C	22.1 %
β^-, n	¹⁶C	63.0 %
β^-, 2n	¹⁵C	11.0 %
β^-, 3n	¹⁴C	3.5 %
β^-, 4n	¹³C	0.40 %

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 12) and isobaric (same nucleon number A = 17) with Boron-17. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 12	Isobar A = 17
4	¹⁶Be
5	¹⁷B	¹⁷B
6	¹⁸C	¹⁷C
7	¹⁹N	¹⁷N
8	²⁰O	¹⁷O
9	²¹F	¹⁷F
10	²²Ne	¹⁷Ne
11	²³Na	¹⁷Na
12	²⁴Mg
13	²⁵Al
14	²⁶Si
15	²⁷P
16	²⁸S
17	²⁹Cl
18	³⁰Ar

External data and identifiers

Adopted Levels, Gammas:NuDat 17B

Literature and References

[1] - J. D. Bowman, A. M. Poskanzer, R. G. Korteling, G. W. Butler:
Discovery of Two Isotopes, ¹⁴Be and ¹⁷B, at the Limits of Particle Stability.
In: Physical Review Letters, 31,614, (1973), DOI 10.1103/PhysRevLett.31.614.