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Oxygen-12

Properties and data of the isotope 12O.


Contents

 

Oxygen-12 isotope

Oxygen-12 is a radioisotope of the chemical element oxygen, which has 4 neutrons in its atomic nucleus in addition to the element-specific 8 protons; the sum of the number of these atomic nucleus building blocks results in a mass number of 12. The very short-lived, only artificially produced, unstable and thus radioactive nuclide has no practical significance; the study of 12O is exclusively for academic purposes.

The discovery of the proton-rich isotope was first reported in 1978. According to this, oxygen-12 was formed as a product of the irradiation of oxygen-16 with α-particles (helium-4 nuclei) accelerated to 117 MeV, according to the following transfer reaction [1]:

16O(4He,8He)12O.

See also: list of Oxygen isotopes.

 

General data

Name of the isotope:Oxygen-12; O-12Symbol:12O or 128OMass number A:12 (= number of nucleons)Atomic number Z:8 (= number of protons)Neutrons N:4Isotopic mass:12.034368(13) u (atomic weight of Oxygen-12)Nuclide mass:12.0299794 u (calculated nuclear mass without electrons)Mass excess:32.01359 MeVMass defect:0.062891919999998 u (per nucleus)Nuclear binding energy:58.58344613 MeV (per nucleus)
4.88195384 MeV (average binding energy per nucleon)
Separation energy:SN = 23.797(61) MeV (first neutron)Half-life:8.9(33) zsDecay constant λ:7.788170568089 × 10+19 s-1Specific activity α:3.908455016853 × 10+42 Bq g-1
1.056339193744 × 10+32 Ci g-1
Spin and parity:
(nuclear angular momentum)
0+Isobaric spin: 2Mirror nucleus:Beryllium-12Year of discovery:1977

 

Radioactive Decay

Half-life T½ = 8.9(33) zs respectively 8.9 × 10-21 seconds s.

Decay
mode
DaughterProbabilityDecay energyγ energy
(intensity)
2p10C14.675(12) MeV

 

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 4) and isobaric (same nucleon number A = 12) with Oxygen-12. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

 

ZIsotone N = 4Isobar A = 12
15H
26He
37Li12Li
48Be12Be
59B12B
610C12C
711N12N
812O12O
913F

 

External data and identifiers

Adopted Levels, Gammas:NuDat 12O

 

Literature and References

[1] - G. J. KeKelis, M. S. Zisman, D. K. Scott et al.:
Masses of the unbound nuclei 16Ne, 15F, and 12O.
In: Physical Review C, 17, 1929, (1978), DOI 10.1103/PhysRevC.17.1929.

 


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Last update: 2024-10-03


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