Oxygen-16

Properties and data of the isotope ¹⁶O.

Contents

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:S_N = 15.6639(5) MeV (first neutron)
S_P = 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

Parent Nuclides

Direct parent isotope is: ¹⁶N.

Occurrence

Comparison of the natural Oxygen isotopes including isotopic abundance (mole fraction of the isotope mixture in percent):

	Atomic Mass m_a	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.

Z	Isotone N = 8	Isobar A = 16
2	¹⁰He
3	¹¹Li
4	¹²Be	¹⁶Be
5	¹³B	¹⁶B
6	¹⁴C	¹⁶C
7	¹⁵N	¹⁶N
8	¹⁶O	¹⁶O
9	¹⁷F	¹⁶F
10	¹⁸Ne	¹⁶Ne
11	¹⁹Na
12	²⁰Mg
13	²¹Al
14	²²Si