Oxygen-16 is a stable isotope of the chemical element oxygen, which has 8 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 16. According to a report, 16O was recognized as an independent isotope in 1919 [1].
See also: List of individual Oxygen isotopes (and general data sources).
General data
Name of the isotope:Oxygen-16; O-16Symbol:16O or 168OMass number A:16 (= number of nucleons)Atomic number Z:8 (= number of protons)Neutrons N:8Nucleon pairing (Z - N):even - evenNuclear ratio (N/Z ratio):1 (= neutron-proton ratio)Neutron excess (N-Z):0Isotopic mass:15.994914619(1) u (atomic weight of Oxygen-16)Nuclide mass:15.990526 u (calculated nuclear mass without electrons)Mass excess:-4.737 MeVMass defect:0.137004965 u (per nucleus)Nuclear binding energy:127.61930287 MeV (per nucleus) 7.97620643 MeV (average binding energy per nucleon)Separation energy:SN = 15.6639(5) MeV (first neutron) SP = 12.127(4) MeV (first proton)Half-life:stableSpin and parity: (nuclear angular momentum)0+Isobaric spin: 0Charge radius:2.6991(52) femtometer fmYear of discovery:1919
Comparison of the natural Oxygen isotopes including isotopic abundance (mole fraction of the isotope mixture in percent):
Atomic Mass ma
Quantity
Half-life
Spin
Oxygen Isotopic mixture
15.999 u
100 %
Isotope 16O
15.994914619(1) u
99.757 % [99.738 - 99.776 %]
stable
0+
Isotope 17O
16.999131757(5) u
0.03835(96) % [0.0367 - 0.0400 %]
stable
5/2+
Isotope 18O
17.999159613(5) u
0.2045 % [0.187 - 0.222 %]
stable
0+
Isotones and Isobars
The following table shows the atomic nuclei that are isotonic (same neutron number N = 8) and isobaric (same nucleon number A = 16) with Oxygen-16. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
