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Oxygen-16 (symbol: 16O or 16
8O
) is a nuclide. It is a stable isotope of oxygen, with 8 neutrons and 8 protons in its nucleus, and when not ionized, 8 electrons orbiting the nucleus. Oxygen-16 has a mass of 15.99491461956 u. It is the most abundant isotope of oxygen and accounts for 99.757% of oxygen's natural abundance.[2]
| General | |
|---|---|
| Symbol | 16O |
| Names | oxygen-16, 16O, O-16 |
| Protons (Z) | 8 |
| Neutrons (N) | 8 |
| Nuclide data | |
| Natural abundance | 99.76% |
| Half-life (t1/2) | stable |
| Isotope mass | 15.99491461956 Da |
| Spin | 0 |
| Excess energy | −4737.00135(16)[1] keV |
| Isotopes of oxygen Complete table of nuclides | |
The relative and absolute abundances of oxygen-16 are high because it is a principal product of stellar evolution and because it is a primordial isotope, meaning it can be made by stars that were initially made exclusively of hydrogen.
Most oxygen-16 is synthesized at the end of the helium fusion process in stars; the triple-alpha process creates carbon-12, which captures an additional helium-4 to make oxygen-16. The neon-burning process also makes it.
Oxygen-16 is doubly magic.
Solid samples (organic and inorganic) for oxygen-16 studies are usually stored in silver cups and measured with pyrolysis and mass spectrometry.[3] Researchers need to avoid improper or prolonged storage of the samples for accurate measurements.[3]
Originally, one atomic mass unit was defined as one sixteenth of the mass of oxygen-16, but the atomic mass unit has since been redefined as one twelfth of the mass of carbon-12.
References
edit- ^ 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): 030003–8. doi:10.1088/1674-1137/41/3/030003.
- ^ "Table of Isotopic Masses and Natural Abundances" (PDF). North Carolina State University. Archived from the original (PDF) on August 25, 2016. Retrieved October 4, 2024.
- ^ a b Tsang, Man-Yin; Yao, Weiqi; Tse, Kevin (2020). Kim, Il-Nam (ed.). "Oxidized silver cups can skew oxygen isotope results of small samples". Experimental Results. 1: e12. doi:10.1017/exp.2020.15. ISSN 2516-712X.
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