Isotopes of oxygen - AbsoluteAstronomy.com

There are three stable isotopes of oxygen that lead to oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

(O) having a standard atomic mass of 15.9994(3) u. 17 radioactive isotopes have also been characterized, with mass number

Mass number

The mass number , also called atomic mass number or nucleon number, is the total number of protons and neutrons in an atomic nucleus. Because protons and neutrons both are baryons, the mass number A is identical with the baryon number B as of the nucleus as of the whole atom or ion...

s from ¹²O to ²⁸O, all short-lived, with the longest-lived being ¹⁵O with a half-life of 122.24 seconds. The shortest-lived is ¹²O with a half-life of 0.4 MeV.

Stable isotopes

Naturally occurring oxygen is composed of three stable isotope

Isotope

Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...

s, ¹⁶O, ¹⁷O

Oxygen-17

Oxygen-17 is a low abundant isotope of oxygen . Being the only stable isotope of oxygen possessing a nuclear spin and the unique characteristic of field-independent relaxation it enables NMR studies of metabolic pathways of compounds incorporating oxygen at high magnetic fields Oxygen-17 is a low...

, and ¹⁸O

Oxygen-18

Oxygen-18 is a natural, stable isotope of oxygen and one of the environmental isotopes.18O is an important precursor for the production of fluorodeoxyglucose used in positron emission tomography...

, with ¹⁶O being the most abundant (99.762% natural abundance

Natural abundance

In chemistry, natural abundance refers to the abundance of isotopes of a chemical element as naturally found on a planet. The relative atomic mass of these isotopes is the atomic weight listed for the element in the periodic table...

). Known oxygen isotopes range in mass number

Mass number

from 12 to 28.

The relative and absolute abundance of ¹⁶O is high because it is a principal product of stellar evolution

Stellar evolution

Stellar evolution is the process by which a star undergoes a sequence of radical changes during its lifetime. Depending on the mass of the star, this lifetime ranges from only a few million years to trillions of years .Stellar evolution is not studied by observing the life of a single...

and because it is a primary isotope, meaning it can be made by star

Star

A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...

s that were initially made exclusively of hydrogen

Hydrogen

Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

. Most ¹⁶O is synthesized

Nucleosynthesis

Nucleosynthesis is the process of creating new atomic nuclei from pre-existing nucleons . It is thought that the primordial nucleons themselves were formed from the quark–gluon plasma from the Big Bang as it cooled below two trillion degrees...

at the end of the helium fusion

Helium fusion

Helium fusion is a kind of nuclear fusion, with the nuclei involved being helium.The fusion of helium-4 nuclei is known as the triple-alpha process, because fusion of just two helium nuclei only produces beryllium-8, which is unstable and breaks back down to two helium nuclei with a half-life of...

process in star

Star

s; the triple-alpha reaction creates ¹²C

Carbon

Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...

, which captures an additional ⁴He

Helium

Helium is the chemical element with atomic number 2 and an atomic weight of 4.002602, which is represented by the symbol He. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table...

to make ¹⁶O. The neon burning process

Neon burning process

The neon-burning process is a set of nuclear fusion reactions that take place in massive stars . Neon burning requires high temperatures and densities ....

creates additional ¹⁶O.

Both ¹⁷O

Oxygen-17

and ¹⁸O

Oxygen-18

Oxygen-18 is a natural, stable isotope of oxygen and one of the environmental isotopes.18O is an important precursor for the production of fluorodeoxyglucose used in positron emission tomography...

are secondary isotopes, meaning that their nucleosynthesis requires seed nuclei. ¹⁷O

Oxygen-17

is primarily made by the burning of hydrogen into helium during the CNO cycle

CNO cycle

The CNO cycle is one of two sets of fusion reactions by which stars convert hydrogen to helium, the other being the proton–proton chain. Unlike the proton–proton chain reaction, the CNO cycle is a catalytic cycle. Theoretical models show that the CNO cycle is the dominant source of energy in stars...

, making it a common isotope in the hydrogen burning zones of stars. Most ¹⁸O

Oxygen-18

Oxygen-18 is a natural, stable isotope of oxygen and one of the environmental isotopes.18O is an important precursor for the production of fluorodeoxyglucose used in positron emission tomography...

is produced when ¹⁴N

Nitrogen

Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...

(made abundant from CNO burning) captures a ⁴He nucleus, making ¹⁸O

Oxygen-18

Oxygen-18 is a natural, stable isotope of oxygen and one of the environmental isotopes.18O is an important precursor for the production of fluorodeoxyglucose used in positron emission tomography...

common in the helium-rich zones of stars. Approximately a billion degrees Celsius is required for two oxygen nuclei to undergo nuclear fusion

Nuclear fusion

Nuclear fusion is the process by which two or more atomic nuclei join together, or "fuse", to form a single heavier nucleus. This is usually accompanied by the release or absorption of large quantities of energy...

to form the heavier nucleus of sulfur

Sulfur

Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

Radioisotopes

Fourteen radioisotopes have been characterized, with the most stable being ¹⁵O with a half-life

Half-life

Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...

of 122.24 s and ¹⁴O with a half-life of 70.606 s. All of the remaining radioactive

Radioactive decay

Radioactive decay is the process by which an atomic nucleus of an unstable atom loses energy by emitting ionizing particles . The emission is spontaneous, in that the atom decays without any physical interaction with another particle from outside the atom...

isotopes have half-lives that are less than 27 s and the majority of these have half-lives that are less than 83 millisecond

Millisecond

A millisecond is a thousandth of a second.10 milliseconds are called a centisecond....

s (ms). For example, ²⁴O has a half-life of 61 ms. The most common decay mode for isotopes lighter than the stable isotopes is β⁺ decay

Positron emission

Positron emission or beta plus decay is a type of beta decay in which a proton is converted, via the weak force, to a neutron, releasing a positron and a neutrino....

(to nitrogen

Nitrogen

) and the most common mode after is β^- decay

Beta decay

In nuclear physics, beta decay is a type of radioactive decay in which a beta particle is emitted from an atom. There are two types of beta decay: beta minus and beta plus. In the case of beta decay that produces an electron emission, it is referred to as beta minus , while in the case of a...

(to fluorine

Fluorine

Fluorine is the chemical element with atomic number 9, represented by the symbol F. It is the lightest element of the halogen column of the periodic table and has a single stable isotope, fluorine-19. At standard pressure and temperature, fluorine is a pale yellow gas composed of diatomic...

).

An atomic mass of 16 was assigned to oxygen prior to the definition of the unified atomic mass unit

Atomic mass unit

The unified atomic mass unit or dalton is a unit that is used for indicating mass on an atomic or molecular scale. It is defined as one twelfth of the rest mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state, and has a value of...

based upon ¹²C. Since physicists referred to ¹⁶O only, while chemists meant the naturally-abundant mixture of isotopes, this led to slightly different mass scales between the two disciplines.

The isotopic composition of oxygen atom

Atom

The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...

s in the Earth's atmosphere is 99.759% ¹⁶O, 0.037% ¹⁷O

Oxygen-17

and 0.204% ¹⁸O

Oxygen-18

Oxygen-18 is a natural, stable isotope of oxygen and one of the environmental isotopes.18O is an important precursor for the production of fluorodeoxyglucose used in positron emission tomography...

. Because water

Water

Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

molecules containing the lighter isotope are slightly more likely to evaporate

Evaporation

Evaporation is a type of vaporization of a liquid that occurs only on the surface of a liquid. The other type of vaporization is boiling, which, instead, occurs on the entire mass of the liquid....

and fall as precipitation

Precipitation (meteorology)

In meteorology, precipitation In meteorology, precipitation In meteorology, precipitation (also known as one of the classes of hydrometeors, which are atmospheric water phenomena is any product of the condensation of atmospheric water vapor that falls under gravity. The main forms of precipitation...

, fresh water

Water

and polar ice on earth contains slightly less (0.1981%) of the heavy isotope ¹⁸O

Oxygen-18

Oxygen-18 is a natural, stable isotope of oxygen and one of the environmental isotopes.18O is an important precursor for the production of fluorodeoxyglucose used in positron emission tomography...

than air (0.204%) or seawater

Seawater

Seawater is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% . This means that every kilogram of seawater has approximately of dissolved salts . The average density of seawater at the ocean surface is 1.025 g/ml...

containing (0.1995%). This disparity allows analysis of temperature patterns via historic ice cores.

Oxygen-13

Oxygen-13 is an unstable isotope

Isotope

of oxygen to provide any nutrients outside of the zone. It consists of 8 protons and electrons, and 5 neutrons. It has a spin of 3/2-, and a half-life

Half-life

of 8.58 ms

Millisecond

A millisecond is a thousandth of a second.10 milliseconds are called a centisecond....

. Its atomic mass is 13.0248 amu

Atomic mass unit

. It decays to Nitrogen

Nitrogen

-13 by electron capture, and has a decay energy of 17.765 MeV

MEV

MeV and meV are multiples and submultiples of the electron volt unit referring to 1,000,000 eV and 0.001 eV, respectively.Mev or MEV may refer to:In entertainment:* Musica Elettronica Viva, an Italian musical group...

. Its parent nuclide is Fluorine

Fluorine

-14. It was created by Rutherford by bombarding N₂ with alpha particles creating ¹³O₂ and H nuclei.

Oxygen-15

Oxygen-15 is an isotope

Isotope

of oxygen, frequently used in positron emission tomography, or PET

Positron emission tomography

Positron emission tomography is nuclear medicine imaging technique that produces a three-dimensional image or picture of functional processes in the body. The system detects pairs of gamma rays emitted indirectly by a positron-emitting radionuclide , which is introduced into the body on a...

experiments. It has 8 protons, 7 neutrons, and 8 electrons. The total atomic mass is 15.0030654 amu. It has a half-life

Half-life

of 122 seconds.

Table

nuclide symbol	Z(p Proton The proton is a subatomic particle with the symbol or and a positive electric charge of 1 elementary charge. One or more protons are present in the nucleus of each atom, along with neutrons. The number of protons in each atom is its atomic number.... )	N(n Neutron The neutron is a subatomic hadron particle which has the symbol or , no net electric charge and a mass slightly larger than that of a proton. With the exception of hydrogen, nuclei of atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons. The number of... )	isotopic mass (u)	half-life	decay mode(s)	daughter isotope(s)Bold for stable isotopes	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
¹²O	8	4	12.034405(20)	580(30)×10⁻²⁴ s [0.40(25) MeV]	2p Proton emission Proton emission is a type of radioactive decay in which a proton is ejected from a nucleus. Proton emission can occur from high-lying excited states in a nucleus following a beta decay, in which case the process is known as beta-delayed proton emission, or can occur from the ground state of very... (60.0%)	¹⁰C	0+
¹²O	8	4	12.034405(20)	580(30)×10⁻²⁴ s [0.40(25) MeV]	β⁺ Beta decay In nuclear physics, beta decay is a type of radioactive decay in which a beta particle is emitted from an atom. There are two types of beta decay: beta minus and beta plus. In the case of beta decay that produces an electron emission, it is referred to as beta minus , while in the case of a... (40.0%)	¹²N	0+
¹³O	8	5	13.024812(10)	8.58(5) ms	β⁺ (89.1%)	¹³N	(3/2-)
¹³O	8	5	13.024812(10)	8.58(5) ms	β⁺, p (10.9%)	¹²C	(3/2-)
¹⁴O	8	6	14.00859625(12)	70.598(18) s	β⁺	¹⁴N	0+
¹⁵O	8	7	15.0030656(5)	122.24(16) s	β⁺	¹⁵N	1/2-
¹⁶OThe ratio between ¹⁶O and ¹⁸O is used to deduce ancient temperatures	8	8	15.99491461956(16)	Stable			0+	0.99757(16)	0.99738-0.99776
¹⁷O Oxygen-17 Oxygen-17 is a low abundant isotope of oxygen . Being the only stable isotope of oxygen possessing a nuclear spin and the unique characteristic of field-independent relaxation it enables NMR studies of metabolic pathways of compounds incorporating oxygen at high magnetic fields Oxygen-17 is a low... Can be used in NMR studies of metabolic pathways	8	9	16.99913170(12)	Stable			5/2+	3.8(1)×10⁻⁴	3.7×10⁻⁴-4.0×10⁻⁴
¹⁸O Oxygen-18 Oxygen-18 is a natural, stable isotope of oxygen and one of the environmental isotopes.18O is an important precursor for the production of fluorodeoxyglucose used in positron emission tomography... Can be used in studying certain metabolic pathways	8	10	17.9991610(7)	Stable			0+	2.05(14)×10⁻³	1.88×10⁻³-2.22×10⁻³
¹⁹O	8	11	19.003580(3)	26.464(9) s	β⁻	¹⁹F	5/2+
²⁰O	8	12	20.0040767(12)	13.51(5) s	β⁻	²⁰F	0+
²¹O	8	13	21.008656(13)	3.42(10) s	β⁻	²¹F	(1/2,3/2,5/2)+
²²O	8	14	22.00997(6)	2.25(15) s	β⁻ (78.0%)	²²F	0+
²²O	8	14	22.00997(6)	2.25(15) s	β⁻, n Neutron emission Neutron emission is a type of radioactive decay of atoms containing excess neutrons, in which a neutron is simply ejected from the nucleus. Two examples of isotopes which emit neutrons are helium-5 and beryllium-13... (22.0%)	²¹F	0+
²³O	8	15	23.01569(13)	82(37) ms	β⁻, n (57.99%)	²²F	1/2+#
²³O	8	15	23.01569(13)	82(37) ms	β⁻ (42.0%)	²¹F	1/2+#
²⁴O	8	16	24.02047(25)	65(5) ms	β⁻, n (57.99%)	²³F	0+
²⁴O	8	16	24.02047(25)	65(5) ms	β⁻ (42.01%)	²⁴F	0+
²⁵O	8	17		5.2×10⁻⁸s	n	²⁴O
²⁶O	8	18		4.0×10⁻⁸ s	β⁻	²⁶F
²⁶O	8	18		4.0×10⁻⁸ s	n	²⁵O

Oxygen isotopes with more than 24 nucleons are physically impossible, since they would be beyond the neutron drip line.

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