Heim

Isotopes

Hydrogen

1H	1	0	1.007825031898(14)	Stable			1/2+	[0.99972, 0.99999]		Protium
2H (D)	1	1	2.014101777844(15)	Stable			1+	[0.00001, 0.00028]		Deuterium
3H (T)	1	2	3.016049281320(81)	12.32(2) y	β−	3He	1/2+	Trace		Tritium
4H	1	3	4.02643(11)	139(10) ys	n	3H	2−
5H	1	4	5.03531(10)	86(6) ys	2n	3H	(1/2+)
6H	1	5	6.04496(27)	294(67) ys	n ?	5H ?	2−#
					3n ?	3H ?
7H	1	6	7.052750(108)#	652(558) ys	2n ?	5H ?	1/2+#

Hydrogen-1 (protium)

¹H(atomic mass 1.007825031898(14) Da) is the most common hydrogen isotope with an abundance of more than 99.98%. Because the nucleus of this isotope consists of only a single proton, it is given the formal name protium.

The proton has never been observed to decay, and hydrogen-1 is therefore considered a stable isotope. Some grand unified theories proposed in the 1970s predict that proton decay can occur with a half-life between 10²⁸ and 10³⁶ years. If this prediction is found to be true, then hydrogen-1 (and indeed all nuclei now believed to be stable) are only observationally stable. To date, experiments have shown that the minimum mean lifetime of the proton is in excess of 3.6×10²⁹ years.

Hydrogen-2 (deuterium)

²H(atomic mass 2.014101777844(15) Da), the other stable hydrogen isotope, is known as deuterium and contains one proton and one neutron in its nucleus. The nucleus of deuterium is called a deuteron. Deuterium comprises 0.0026–0.0184% (by population, not by mass) of hydrogen samples on Earth, with the lower number tending to be found in samples of hydrogen gas and the higher enrichment (0.015% or 150 ppm) typical of ocean water. Deuterium on Earth has been enriched with respect to its initial concentration in the Big Bang and the outer solar system (about 27 ppm, by atom fraction) and its concentration in older parts of the Milky Way galaxy (about 23 ppm). Presumably the differential concentration of deuterium in the inner solar system is due to the lower volatility of deuterium gas and compounds, enriching deuterium fractions in comets and planets exposed to significant heat from the Sun over billions of years of solar system evolution.

Deuterium is not radioactive, and does not represent a significant toxicity hazard. Water enriched in molecules that include deuterium instead of protium is called heavy water. Deuterium and its compounds are used as a non-radioactive label in chemical experiments and in solvents for H¹-nuclear magnetic resonance spectroscopy. Heavy water is used as a neutron moderator and coolant for nuclear reactors. Deuterium is also a potential fuel for commercial nuclear fusion.

Hydrogen-3 (tritium)

³H(atomic mass 3.016049281320(81) Da) is known as tritium and contains one proton and two neutrons in its nucleus. It is radioactive, decaying into helium-3 through β− decay with a half-life of 12.32(2) years.Trace amounts of tritium occur naturally because of the interaction of cosmic rays with atmospheric gases. Tritium has also been released during nuclear weapons tests. It is used in thermonuclear fusion weapons, as a tracer in isotope geochemistry, and specialized in self-powered lighting devices.

The most common method of producing tritium is by bombarding a natural isotope of lithium, lithium-6, with neutrons in a nuclear reactor.

Tritium was once used routinely in chemical and biological labeling experiments as a radioactive tracer. This has become less common, but still happens. D-T nuclear fusion uses tritium as its main reactant, along with deuterium, liberating energy through the loss of mass when the two nuclei collide and fuse at high temperatures.

Hydrogen-4

⁴H (atomic mass 4.02643(11)) contains one proton and three neutrons in its nucleus. It is an unbound nuclear drop, too unstable to qualify as a nuclide. It has been synthesized in the laboratory by bombarding tritium with fast-moving deuterium nuclei. In this experiment, the tritium nucleus captured a neutron from the fast-moving deuterium nucleus. The presence of the hydrogen-4 was deduced by detecting the emitted protons. It decays through neutron emission into hydrogen-3 (tritium) with a half-life of 139(10) ys (or 1.39(10)×10⁻²² s).

In the 1955 satirical novel The Mouse That Roared, the name quadium was given to the hydrogen-4 isotope that powered the Q-bomb that the Duchy of Grand Fenwick captured from the United States.

Hydrogen-5

⁵H (atomic mass 5.03531(10)) is an unbound nuclear drop, too unstable to be a true nuclide. The nucleus consists of a proton and four neutrons. It has been synthesized in the laboratory by bombarding tritium with fast-moving tritium nuclei. In this experiment, one tritium nucleus captures two neutrons from the other, becoming a nucleus with one proton and four neutrons. The remaining proton may be detected, and the existence of hydrogen-5 deduced. It decays through double neutron emission into hydrogen-3 (tritium) and has a half-life of 86(6) ys (8.6(6)×10⁻²³ s) - the shortest half-life of any known nuclide - and approaching the causality limit at which information about what is in a particle cannot be transmitted to all parts of the particle before another change occurs.

Hydrogen-6

⁶H(atomic mass 6.04496(27)) is an unbound nuclear drop which decays by neutron emission. (In practice, the decay goes ⁶H --> ⁵H + n, ⁵H --> ⁴H + n, and ⁴H --> ³H + n, which can be summarized as triple neutron emission into hydrogen-3. Since ³H itself beta decays, that fourth beta decay sometimes occurs right after the first three, so ⁶H --> ²H + 4n is sometimes observed. Mean life of ⁶H is 2.94(67)×10⁻²² s.

Hydrogen-7

⁷H (atomic mass 7.05275(108)) consists of a proton and six neutrons. It was first synthesized in 2003 by a group of Russian, Japanese and French scientists at RIKEN's Radioactive Isotope Beam Factory by bombarding hydrogen with helium-8 atoms. In the resulting reaction, all six of the helium-8 neutrons were donated to the hydrogen's nucleus. The two remaining protons were detected by the "RIKEN telescope", a device composed of several layers of sensors, positioned behind the target of the RI Beam cyclotron. Hydrogen-7 has a half life of 6.5×10⁻²² s.

Decay chains

The majority of heavy hydrogen isotopes decay directly to ³H, which then decays to the stable isotope ³He. However, ⁶H has occasionally been observed to decay directly to stable ²H.

Helium

Nuclide	Z	N	Isotopic mass (Da)	Half-life [resonance width]	Decay mode	Daughter isotope	Spin and parity	Natural abundance
								Normal proportion	Range of variation
2He	2	0	2.015894(2)	10−22 s	p (> 99.99%)	1H	0+#
					β+ (< 0.01%)	2H
3He	2	1	3.016029321967(60)	Stable			1/2+	0.000002(2)	[4.6×10−10, 0.000041]
4He	2	2	4.002603254130(158)	Stable			0+	0.999998(2)	[0.999959, 1.000000]
5He	2	3	5.012057(21)	602(22) ys [758(28) keV]	n	4He	3/2−
6He	2	4	6.01888589(6)	806.92(24) ms	β− (99.999722(18)%)	6Li	0+
					β−d (0.000278(18)%)	4He
7He	2	5	7.027991(8)	2.51(7) zs [182(5) keV]	n	6He	(3/2)−
8He	2	6	8.03393439(10)	119.5(1.5) ms	β− (83.1(1.0)%)	8Li	0+
					β−n (16(1)%)	7Li
					β−t (0.9(1)%)	5He
9He	2	7	9.043950(50)	2.5(2.3) zs	n	8He	1/2(+)
10He	2	8	10.05282(10)	260(40) ys [1.76(27) MeV]	2n	8He	0+

Helium-2 (diproton)

Heliun 2, ,²He, is a species of nuclear drop. Even though it is not stable enough to qualify as a nuclide, it is abundantly present in the universe. Because if its great importance, it has its own article, "Diproton", on this wiki. Refer to that article for information about diproton as a nuclear drop and its (essential) role in making the sun work.

This article address observations of diproton and speculation about both cosmology and high-energy physics. It should be regarded as a springboard for study rather than reliable information.

According to theoretical calculations, it would have been much more stable (although still undergoing β+ decay to deuterium) if the strong interaction had been 2% greater^{(citation needed)}. Its instability is due to spin–spin interactions in the nuclear force, which forces the two protons to have anti-aligned spins and gives the diproton a negative binding energy^{(arXiv: 1005.2014v1 [nucl.ex] 12 May, 2010 perhaps?)}. In 2000, a team of physicists, led by Alfredo Galindo-Uribarri of the Oak Ridge National Laboratory, observed simultaneous and collimated emission of two protons from ¹⁸Ne decay^{(citation needed)}. Athough it is possible for a nuclide to emit two protons simultaneously (to within 10^-23 sec) and to emit them in approximately the same direction, it is more likely that decay proceeded by emission of one ²He particle which decayed into two protons. The experiment was not sensitive enough to establish which of these two processes was taking place. Later experiments in 2008 at the Istituto Nazionale di Fisica Nucleare, in Italy was able to confirm that ¹⁸Ne does indeed emit a single diproton particle rather than a closely-spaced pair^{(citation needed)}. Further evidence comes from RIKEN in Japan and the Joint Institute for Nuclear Research in Dubna, Russia, where beams of ⁶He nuclei were directed at a cryogenic hydrogen target to produce ⁵He . In the course of these experiments, the reaction ⁶He + p --> ⁵H + 2p was observed, although it was not possible to distinguish diproton emission for correlated, but independent, proton emissions^{(citation needed)}.

The hypothetical effect of the binding of the diproton on Big Bang and stellar nucleosynthesis has been investigated. Some models suggest that variations in the strong force allowing the existence of a bound diproton would enable the conversion of all primordial hydrogen to helium in the Big Bang, with catastrophic consequences on the development of stars and life. This proposition is used as an example of the anthropic principle. However, a 2009 study suggests that such a conclusion cannot be drawn, as the formed diprotons would still decay to deuterium, whose binding energy would also increase. In some scenarios, it is postulated that hydrogen (in the form of deuterium) could still survive in relatively large quantities, rebutting arguments that the strong force is tuned within a precise anthropic limit.

Helium-3

³He is stable and is the only stable nuclide other than ¹H with more protons than neutrons. [There are 165 known or predicted unstable nuclei, plus another 73 predicted nuclear drops too unstable to be nuclides⁽¹⁾.] There is only a trace amount (0.000002(2)) of ³He on Earth, primarily present since the formation of the Earth, although some falls to Earth trapped in cosmic dust. Trace amounts are also produced by the beta decay of tritium formed by capture of solar neutrons,

³He is present in large quantity in all stars as an intermediate step in the proton-proton reaction chain. It is also the major product of deuterium burning in brown dwarfs.

For helium-3 to form a superfluid, it must be cooled to a temperature of 0.0025 K, or almost a thousand times lower than helium-4 (2.17 K). This difference is explained by quantum statistics, since helium-3 atoms are fermions, while helium-4 atoms are bosons, which condense to a superfluid more easily.

Helium-4

The most common isotope, ⁴He , is produced on Earth by alpha decay of heavier radioactive elements; the alpha particles that emerge are fully ionized ⁴He nuclei. ⁴He is an unusually stable nucleus because its nucleons are arranged into complete shells. It was also formed in enormous quantities during Big Bang nucleosynthesis.

Terrestrial helium consists almost exclusively (0.999998(2)) of this isotope. Helium-4's boiling point of 4.2 K is the second lowest of all known substances, second only to helium-3. When cooled further to 2.17 K, it transforms to a unique superfluid state of zero viscosity. It solidifies only at pressures above 25 atmospheres, where its melting point is 0.95 K.

Heavier helium isotopes

Although all heavier helium isotopes decay with a half-life of less than one second, researchers have used particle accelerator collisions to create unusual atomic nuclei for elements such as helium, lithium and nitrogen. The unusual nuclear structures of such isotopes may offer insight into the isolated properties of neutrons.

Although nuclear drops ranging from ²He to 10He are know, only two are long-lived enough to be considered isotopes of the element. Helium-6 decays to ⁶Li by emitting a beta particle, with a half-life of 806.92(24) milliseconds. Helium-8 is a little more exotic. This isotope decays by beta emission to ⁸Li, but beta decay rarely goes from ground state to ground state. Excited 8Li decays in one of three ways: a.) beta emission to give ⁸Be, which promptly splits into a pair of ⁴He nuclei. b,) neutron emission to give ⁷Li, or (since simplicity is boring) c.) ³H emission to give 5He, which promptly ejects a neutron to become 4He.

8He appears to be a "halo" nucleus in which neutrons occupy a considerably larger volume of space than bonded nuclear matter.

Lithium

Nuclide	Z	N	Isotopic mass (Da)	Half-life [resonance width]	Decay mode	Daughter isotope	Spin and parity	Natural abundance
	Excitation energy							Normal proportion	Range of variation
3Li	3	0	3.03078(215)#		p ?	2He ?	3/2−#
4Li	3	1	4.02719(23)	91(9) ys [5.06(52) MeV]	p	3He	2−
5Li	3	2	5.012540(50)	370(30) ys [1.24(10) MeV]	p	4He	3/2−
6Li	3	3	6.0151228874(15)	Stable			1+	[0.019, 0.078]
6mLi	3562.88(10) keV			56(14) as	IT	6Li	0+
7Li	3	4	7.016003434(4)	Stable			3/2−	[0.922, 0.981]
8Li	3	5	8.02248624(5)	838.7(3) ms	β−	8Be	2+
9Li	3	6	9.02679019(20)	178.2(4) ms	β−n (50.5(1.0)%)	8Be	3/2−
					β− (49.5(1.0)%)	9Be
10Li	3	7	10.035483(14)	2.0(5) zs [0.2(1.2) MeV]	n	9Li	(1−, 2−)
10m1Li	200(40) keV			3.7(1.5) zs	IT		1+
10m2Li	480(40) keV			1.35(24) zs [0.350(70) MeV]	IT		2+
11Li	3	8	11.0437236(7)	8.75(6) ms	β−n (86.3(9)%)	10Be	3/2−
					β− (6.0(1.0)%)	11Be
					β−2n (4.1(4)%)	9Be
					β−3n (1.9(2)%)	8Be
					β−α (1.7(3)%)	7He
					β−d (0.0130(13)%)	9Li
					β−t (0.0093(8)%)	8Li
12Li	3	9	12.052610(30)		n ?	11Li ?	(1−, 2−)
13Li	3	10	13.061170(80)	3.3(1.2) zs [0.2(9.2) MeV]	2n	11Li	3/2−#

Lithium-3

Lithium-3, also known as the triproton, would consist of three protons and zero neutrons. It was reported as proton unbound in 1969, but this result was not accepted and its existence is thus unproven. No other resonances attributable to <³Li have been reported, and it is expected to decay by prompt proton emission (much like the diproton, ²He). It should be noted that decay by b⁺ emission to 3He is possible for this nuclear drop.

Lithium-4

Lithium-4 is an unbound nuclear drop containing three protons and one neutron. It decays to 3He by emitting a proton with a half-life of 9.1(9)×10⁻²³ seconds. A small quantity of ⁴Li can form as an intermediate in some nuclear fusion reactions, notably ³He + p.

Lithium-6

Lithium-6 is valuable as the source material for the production of tritium (hydrogen-3) and as an absorber of neutrons in nuclear fusion reactions. Between 1.9% and 7.8% of terrestrial lithium in normal materials consists of lithium-6, with the rest being lithium-7. Large amounts of lithium-6 have been separated out for placing into thermonuclear weapons. The separation of lithium-6 has by now ceased in the large thermonuclear powers, but stockpiles of it remain in these countries.

The deuterium–tritium fusion reaction has been investigated as a possible energy source, as it is currently the only fusion reaction with sufficient energy output for feasible implementation. In this scenario, lithium enriched in lithium-6 would be required to generate the necessary quantities of tritium. Mineral and brine lithium resources are a potential limiting factor in this scenario, but seawater can eventually also be used. Pressurized heavy-water reactors such as the CANDU produce small quantities of tritium in their coolant/moderator from neutron absorption and this is sometimes extracted as an alternative to the use of Lithium-6.

Lithium-6 is one of only three stable isotopes with a spin of 1, the others being deuterium and nitrogen-14, and has the smallest nonzero nuclear electric quadrupole moment of any stable nucleus.

Lithium-7

Lithium-7 is the most abundant isotope of lithium, making up between 92.2% and 98.1% of all terrestrial lithium. A lithium-7 atom contains three protons, four neutrons, and three electrons. It should be noted that both Li isotopes are rare. Neither Big Bang nucleosynthesis nor stellar nucleo-synthesis can make it. Spallation of larger nuclides by high-energy particles is required.

The industrial production of lithium-6 results in a waste product which is enriched in lithium-7 and depleted in lithium-6. This material has been sold commercially, and some of it has been released into the environment. A relative abundance of lithium-7, as high as 35 percent greater than the natural value, has been measured in the ground water in a carbonate aquifer underneath the West Valley Creek in Pennsylvania, which is downstream from a lithium processing plant. The isotopic composition of lithium in normal materials can vary somewhat depending on its origin, which determines its relative atomic mass in the source material. An accurate relative atomic mass for samples of lithium cannot be measured for all sources of lithium.It should be noted in this context that ⁷Li is 14% more massive than ⁶Li. This will be enough so the chemistry of ⁶Li will be subtly different from that of ⁷Li, although the difference will be nowhere as pronounced as the difference between ²H and ¹H.

Lithium-7 is used as a part of the molten lithium fluoride in molten salt reactors: liquid-fluoride nuclear reactors. The large neutron absorption cross section of lithium-6 (about 940 barns) as compared with the very small neutron cross section of lithium-7 (about 45 millibarns) makes high separation of lithium-7 from natural lithium a strong requirement for the possible use in lithium fluoride reactors.

Lithium-7 hydroxide is used for alkalizing of the coolant in pressurized water reactors..

Particles with a nuclear charge of 3 and a total of 7 particles - of which at least one is a Delta baryon - have been produced. (There are 4 delta baryons, so it is by no means clear what the particles actually were.) Those particles are not candidates for being atomic nuclei or even nuclear drops. Particles with baryons other than protons or neutrons resemble nuclei, but are particles of an entirely different type.

Lithium-8

Lithium-8 has been proposed as a source of 6.4 MeV electron antineutrinos generated by the inverse beta decay to Beryllium-8. The ISODAR particle physics collaboration describes a scheme to generated Lithium-8 for immediate decay by bombarding stable Lithium-7 with 60 MeV protons created by a cyclotron particle accelerator.

Lithium-11

Lithium-11 is thought to possess a halo nucleus consisting of a core of three protons and eight neutrons, two of which are in a nuclear halo. It has an exceptionally large cross-section of 3.16 fm², comparable to that of ²⁰⁸Pb. It decays by beta emission and neutron emission to ¹⁰Be, ¹¹Be, or ⁹Be(see tables above).

Lithium 11 may be the single most undecided nuclide ever observed. Technically, that's not quite true - it always beta decays to some excited state of ¹¹Be, which "cools" by a different process depending on which excited state the initial decay reached. Since those subsequent "cooling" emissions happen fast, they're usually combined as a "beta plus something" decay mode. In the case of ¹¹Be, common decay modes are: pure b (6.0 %), b+n (86.3%), b+2n (4.1%), b+3n (1.9%) and b+a (1.7%). In addition, b+²H (deuterium) and b+³H (tritium) each occur about 0.01% of the time. That may sound rare, but it's not by nuclear standards. The comparable fraction for spontaneous fission of ²³⁸U is 0.00005%. That means ¹¹Be has seven normal decay modes. Few nuclei have more than three decay modes. Seven borders on being a joke the universe is playing on us.

Lithium-12

Lithium-12 has an unbound neutron. In substance, such a neutron simply passes through a particle of nuclear matter. A ¹²Li particle lasts as long as it takes for a neutron to travel a few femtometers - figure under 10^-20 sec,

A more elegant way to put that (courtesy of a prior editor) is to say that ¹⁰Li and ¹²Li decay via neutron emission into ⁹Li and ¹¹Li respectively due to their positions beyond the neutron drip line. Lithium-11 produces the spectacular array of decays it shows because it beta decays to a set of excited states of 11Be, most of which contain unbound neutrons.

Beryllium

Nuclide	Z	N	Isotopic mass (Da)	Half-life [resonance width]	Decay mode	Daughter isotope	Spin and parity	Natural abundance
	Excitation energy							Normal proportion	Range of variation
5Be	4	1	5.03987(215)#		p ?	4Li ?	(1/2+)#
6Be	4	2	6.019726(6)	5.0(3) zs [91.6(5.6) keV]	2p	4He	0+
7Be	4	3	7.01692871(8)	53.22(6) d	ε	7Li	3/2−	Trace
8Be	4	4	8.00530510(4)	81.9(3.7) as [5.58(25) eV]	α	4He	0+
8mBe	16626(3) keV				α	4He	2+
9Be	4	5	9.01218306(8)	Stable			3/2−	1
9mBe	14390.3(1.7) keV			1.25(10) as [367(30) eV]			3/2−
10Be	4	6	10.01353469(9)	1.387(12)×106 y	β−	10B	0+	Trace
11Be	4	7	11.02166108(26)	13.76(7) s	β− (96.7(1)%)	11B	1/2+
					β−α (3.3(1)%)	7Li
					β−p (0.0013(3)%)	10Be
11mBe	21158(20) keV			0.93(13) zs [500(75) keV]	IT ?[n 7]	11Be ?	3/2−
12Be	4	8	12.0269221(20)	21.46(5) ms	β− (99.50(3)%)	12B	0+
					β−n (0.50(3)%)	11B
12mBe	2251(1) keV			233(7) ns	IT	12Be	0+
13Be	4	9	13.036135(11)	1.0(7) zs	n ?	12Be ?	(1/2−)
13mBe	1500(50) keV						(5/2+)
14Be	4	10	14.04289(14)	4.53(27) ms	β−n (86(6)%)	13B	0+
					β− (> 9.0(6.3)%)	14B
					β−2n (5(2)%)	12B
					β−t (0.02(1)%)	11Be
					β−α (< 0.004%)	10Li
14mBe	1520(150) keV						(2+)
15Be	4	11	15.05349(18)	790(270) ys	n	14Be	(5/2+)
16Be	4	12	16.06167(18)	650(130) ys [0.73(18) MeV]	2n	14Be	0+

Beryllium 10

This isotope of Be is astonishingly stable for such a small nuclide. It's half-life is 1.51E6 years, a value not exceeded until ⁵³Mn, with its 3.74E6 yr half life. Its decay energy is reported as Q(b) = 557 keV. That is normally enough energy to produce a half-life of minutes (compare it with ³H's 18.6 keV and 12.32 yr half-life). ¹⁰Be is a very small example of a radionuclide which can only decay by unlikely ("forbidden") channels. ⁵³Mn, it should be noted, has a Q(b) of 597 keV, so it, too, is stabilized by decay constraints rather than lack of energy release,

Decay Modes

There are a total of six isotopes of Be, all but one of which decay by beta emission. Heavier isotopes show b+xn decay as well as pure b. Beryllium 7 decays by electron capture (equivalent to b⁺ in its effects). This nuclide is one of the few whose decay rate is measurably influenced by its chemical environment - its half-life can be artificially lowered by 0.83% via endohedral enclosure (⁷Be@C₆₀).

But the real star of the show is ⁸Be, which turns into a pair of alpha particles (your choice whether to call it fission or alpha emission). ⁸Be is a nuclear drop, not a bound particle. Specifically, it requires 5.6 eV to force a pair of alpha particle together into a ⁸Be drop. That's the kind of energy which is absorbed or released in a chemical reaction - yet its half-life is 8.2E-17 sec. Unbound particles disintegrate very fast in the nuclear world.

Still, for an unbound particle, ⁸Be has an extraordinarily long half-life. This is good because at temperatures over 100 megaKelvin and densities of several hundred g/cm^3 two ⁴He nuclei can fuse into ⁸Be and a third nucleus fuse with ⁸Be before it has time to decay. This process - called "triple alpha" powers stars late in their lives. By the time the star turns into a white dwarf, it has blown a lot of that carbon into space. That's where the carbon comes from which makes up - among other things - the eyeballs needed to read this paragraph. ⁸Be, along with ²He and ⁶Be are the big three among "honorary nuclides", nuclear drops which play a vital role in processes of widespread importance.

Boron

Nuclide	Z	N	Isotopic mass (Da)	Half-life [resonance width]	Decay mode	Daughter isotope	Spin and parity	Natural abundance
	Excitation energy							Normal proportion	Range of variation
7B	5	2	7.029712(27)	570(14) ys [801(20) keV]	p	6Be	(3/2−)
8B	5	3	8.0246073(11)	771.9(9) ms	β+α	4He	2+
8mB	10624(8) keV						0+
9B	5	4	9.0133296(10)	800(300) zs	p	8Be	3/2−
10B	5	5	10.012936862(16)	Stable			3+	[0.189, 0.204]
11B	5	6	11.009305167(13)	Stable			3/2−	[0.796, 0.811]
11mB	12560(9) keV						1/2+, (3/2+)
12B	5	7	12.0143526(14)	20.20(2) ms	β− (99.40(2)%)	12C	1+
					β−α (0.60(2)%)	8Be
13B	5	8	13.0177800(11)	17.16(18) ms	β− (99.734(36)%)	13C	3/2−
					β−n (0.266(36)%)	12C
14B	5	9	14.025404(23)	12.36(29) ms	β− (93.96(23)%)	14C	2−
					β−n (6.04(23)%)	13C
					β−2n ?	12C?
14mB	17065(29) keV			4.15(1.90) zs	IT ?		0+
15B	5	10	15.031087(23)	10.18(35) ms	β−n (98.7(1.0)%)	14C	3/2−
					β− (< 1.3%)	15C
					β−2n (< 1.5%)	13C
16B	5	11	16.039841(26)	> 4.6 zs	n ?	15B ?	0−
17B	5	12	17.04693(22)	5.08(5) ms	β−n (63(1)%)	16C	(3/2−)
					β− (21.1(2.4)%)	17C
					β−2n (12(2)%)	15C
					β−3n (3.5(7)%)	14C
					β−4n (0.4(3)%)	13C
18B	5	13	18.05560(22)	< 26 ns	n	17B	(2−)
19B	5	14	19.06417(56)	2.92(13) ms	β−n (71(9)%)	18C	(3/2−)
					β−2n (17(5)%)	17C
					β−3n (< 9.1%)	16C
					β− (> 2.9%)	19C
20B	5	15	20.07451(59)	> 912.4 ys	n	19B	(1−, 2−)
21B	5	16	21.08415(60)	> 760 ys	2n	19B	(3/2−)

Applications

Boron-10

Boron-10 is used in boron neutron capture therapy as an experimental treatment of some brain cancers.

Decay Modes

Boron isotopes ¹⁵B and heavier show an alternating pattern of beta and neutron decay, with the odd-neutron species ¹⁶B, ¹⁸B, and ²⁰B decaying by neutron emission. Each has an unbound neutron; which it ejects, leaving behind paired neutrons. They are nuclear drops beyond the neutron dripline. By contrast the lightest even-neutron species which decays by neutron emission is ²¹B.

Carbon

Nuclide	Z	N	Isotopic mass (Da)	Half-life [resonance width]	Decay mode	Daughter isotope	Spin and parity	Natural abundance
								Normal proportion	Range of variation
8C	6	2	8.037643(20)	3.5(1.4) zs [230(50) keV]	2p	6Be	0+
9C	6	3	9.0310372(23)	126.5(9) ms	β+ (54.1(1.7)%)	9B	3/2−
					β+α (38.4(1.6)%)	5Li
					β+p (7.5(6)%)	8Be
10C	6	4	10.01685322(8)	19.3011(15) s	β+	10B	0+
11C	6	5	11.01143260(6)	20.3402(53) min	β+	11B	3/2−
11mC	12160(40) keV				p ?	10B?	1/2+
12C	6	6	12 exactly	Stable			0+	[0.9884, 0.9904]
13C	6	7	13.003354835336(252)	Stable			1/2−	[0.0096, 0.0116]
14C	6	8	14.003241989(4)	5.70(3)×103 y	β−	14N	0+	Trace	< 10−12
14mC	22100(100) keV				IT	14C	(2−)
15C	6	9	15.0105993(9)	2.449(5) s	β−	15N	1/2+
16C	6	10	16.014701(4)	750(6) ms	β−n (99.0(3)%)	15N	0+
					β− (1.0(3)%)	16N
17C	6	11	17.022579(19)	193(6) ms	β− (71.6(1.3)%)	17N	3/2+
					β−n (28.4(1.3)%)	16N
					β−2n ?	15N?
18C	6	12	18.02675(3)	92(2) ms	β− (68.5(1.5)%)	18N	0+
					β−n (31.5(1.5)%)	17N
					β−2n ?	18N ?
19C [n 15]	6	13	19.03480(11)	46.2(2.3) ms	β−n (47(3)%)	18N	1/2+
					β− (46.0(4.2)%)	19N
					β−2n (7(3)%)	17N
20C	6	14	20.04026(25)	16(3) ms	β−n (70(11)%)	19N	0+
					β−2n (< 18.6%)	18N
					β− (> 11.4%)	20N
21C	6	15	21.04900(64)#	< 30 ns	n ?	20C ?	1/2+#
22C	6	16	22.05755(25)	6.2(1.3) ms	β−n (61(14)%)	21N	0+
					β−2n (< 37%)	20N
					β− (> 2%)	22N

Carbon-11

Carbon-11 or ¹¹C is a radioactive isotope of carbon that decays to boron-11. This decay mainly occurs due to positron emission, with around 0.19–0.23% of decays instead occurring by electron capture. It has a half-life of 20.3402(53) min.

¹¹C → ¹¹ B + e⁺ + ν _e + 0.96 MeV

¹¹C + e⁻ → ¹¹ B + ν _e + 1.98 MeV

It is produced from nitrogen in a cyclotron by the reaction

¹⁴N + p → ¹¹ C + ⁴ He

Carbon-11 is commonly used as a radioisotope for the radioactive labeling of molecules in positron emission tomography. Among the many molecules used in this context are the radioligands [¹¹C]DASB and [¹¹C]Cimbi-5.

Natural isotopes

There are three naturally occurring isotopes of carbon: 12, 13, and 14. ¹²C and ¹³C are stable, occurring in a natural proportion of approximately 93:1. ¹⁴C is produced by thermal neutrons from cosmic radiation in the upper atmosphere, and is transported down to earth to be absorbed by living biological material. Isotopically, ¹⁴C constitutes a negligible part; but, since it is radioactive with a half-life of 5.70(3)×10³ years, it is radiometrically detectable. Since dead tissue does not absorb ¹⁴C, the amount of ¹⁴C is one of the methods used within the field of archeology for radiometric dating of biological material.

Paleoclimate

¹²C and ¹³C are measured as the isotope ratio δ¹³C in benthic foraminifera and used as a proxy for nutrient cycling and the temperature dependent air–sea exchange of CO₂ (ventilation). Plants find it easier to use the lighter isotopes (¹²C) when they convert sunlight and carbon dioxide into food. So, for example, large blooms of plankton (free-floating organisms) absorb large amounts of ¹²C from the oceans. Originally, the ¹²C was mostly incorporated into the seawater from the atmosphere. If the oceans that the plankton live in are stratified (meaning that there are layers of warm water near the top, and colder water deeper down), then the surface water does not mix very much with the deeper waters, so that when the plankton dies, it sinks and takes away ¹²C from the surface, leaving the surface layers relatively rich in ¹³C. Where cold waters well up from the depths (such as in the North Atlantic), the water carries ¹²C back up with it. So, when the ocean was less stratified than today, there was much more ¹²C in the skeletons of surface-dwelling species. Other indicators of past climate include the presence of tropical species, coral growths rings, etc.

Nitrogen

Nuclide	Z	N	Isotopic mass (Da)	Half-life [resonance width]	Decay mode	Daughter isotope	Spin and parity	Natural abundance
	Excitation energy							Normal proportion	Range of variation
10N	7	3	10.04165(43)	143(36) ys	p ?	9C ?	1−, 2−
11N	7	4	11.026158(5)	585(7) ys [780.0(9.3) keV]	p	10C	1/2+
11mN	740(60) keV			690(80) ys	p		1/2−
12N	7	5	12.0186132(11)	11.000(16) ms	β+ (98.07(4)%)	12C	1+
					β+α (1.93(4)%)	8Be
13N	7	6	13.00573861(29)	9.965(4) min	β+	13C	1/2−
14N	7	7	14.003074004251(241)	Stable			1+	[0.99578, 0.99663]
14mN	2312.590(10) keV				IT	14N	0+
15N	7	8	15.000108898266(625)	Stable			1/2−	[0.00337, 0.00422]
16N	7	9	16.0061019(25)	7.13(2) s	β− (99.99846(5)%)	16O	2−
					β−α (0.00154(5)%)	12C
16mN	120.42(12) keV			5.25(6) μs	IT (99.999611(25)%)	16N	0−
					β− (0.000389(25)%)	16O
17N	7	10	17.008449(16)	4.173(4) s	β−n (95.1(7)%)	16O	1/2−
					β− (4.9(7)%)	17O
					β−α (0.0025(4)%)	13C
18N	7	11	18.014078(20)	619.2(1.9) ms	β− (80.8(1.6)%)	18O	1−
					β−α (12.2(6)%)	14C
					β−n (7.0(1.5)%)	17O
					β−2n ?[n 8]	16O?
19N	7	12	19.017022(18)	336(3) ms	β− (58.2(9)%)	19O	1/2−
					β−n (41.8(9)%)	18O
20N	7	13	20.023370(80)	136(3) ms	β− (57.1(1.4)%)	20O	(2−)
					β−n (42.9(1.4)%)	19O
					β−2n ?	18O?
21N	7	14	21.02709(14)	85(5) ms	β−n (87(3)%)	20O	(1/2−)
					β− (13(3)%)	21O
					β−2n ?	19O ?
22N	7	15	22.03410(22)	23(3) ms	β− (54.0(4.2)%)	22O	0−#
					β−n (34(3)%)	21O
					β−2n (12(3)%)	20O
23N	7	16	23.03942(45)	13.9(1.4) ms	β− (> 46.6(7.2)%)	23O	1/2−#
					β−n (42(6)%)	22O
					β−2n (8(4)%)	21O
					β−3n (< 3.4%)	20O
24N	7	17	24.05039(43)#	< 52 ns	n ?	23N ?
25N	7	18	25.06010(54)#	< 260 ns	n ?	24N ?	1/2−#
					2n ?[n 8]	23N ?
					β− ?	25O ?

Nitrogen-13

Nitrogen-13 and oxygen-15 are produced in the atmosphere when gamma rays (for example from lightning) knock neutrons out of nitrogen-14 and oxygen-16:

¹⁴N + γ → ¹³N + n

¹⁶O + γ → ¹⁵O + n

The nitrogen-13 produced as a result decays with a half-life of 9.965(4) min to carbon-13, emitting a positron. The positron quickly annihilates with an electron, producing two gamma rays of about 511 keV. After a lightning bolt, this gamma radiation dies down with a half-life of ten minutes, but these low-energy gamma rays go only about 90 metres through the air on average, so they may only be detected for a minute or so as the "cloud" of ¹³N and ¹⁵O floats by, carried by the wind.

Nitrogen-14

Nitrogen-14 is one of two stable (non-radioactive) isotopes of the chemical element nitrogen, which makes about 99.636% of natural nitrogen.

Nitrogen-14 is one of the very few stable nuclides with both an odd number of protons and of neutrons (seven each) and is the only one to make up a majority of its element. Each proton or neutron contributes a nuclear spin of plus or minus spin 1/2, giving the nucleus a total magnetic spin of one.

Like all elements heavier than lithium, the original source of nitrogen-14 and nitrogen-15 in the Universe is believed to be stellar nucleosynthesis, where they are produced as part of the carbon-nitrogen-oxygen cycle.

Nitrogen-14 is the source of naturally-occurring, radioactive, carbon-14. Some kinds of cosmic radiation cause a nuclear reaction with nitrogen-14 in the upper atmosphere of the Earth, creating carbon-14, which decays back to nitrogen-14 with a half-life of 5700(30) years.

Nitrogen-15

Nitrogen-15 is a rare stable isotope of nitrogen. Two sources of nitrogen-15 are the positron emission of oxygen-15 and the beta decay of carbon-15. Nitrogen-15 presents one of the lowest thermal neutron capture cross sections of all isotopes.

Nitrogen-15 is frequently used in NMR (Nitrogen-15 NMR spectroscopy). Unlike the more abundant nitrogen-14, which has an integer nuclear spin and thus a quadrupole moment, ¹⁵N has a fractional nuclear spin of one-half, which offers advantages for NMR such as narrower line width.

Nitrogen-15 tracing is a technique used to study the nitrogen cycle.

Oxygen

Nuclide	Z	N	Isotopic mass (Da)	Half-life [resonance width]	Decay mode	Daughter isotope	Spin and parity	Natural abundance
	Excitation energy							Normal proportion	Range of variation
11O	8	3	11.051250(60)	198(12) ys [2.31(14) MeV]	2p	9C	(3/2−)
12O	8	4	12.034368(13)	8.9(3.3) zs	2p	10C	0+
13O	8	5	13.024815(10)	8.58(5) ms	β+ (89.1(2)%)	13N	(3/2−)
					β+p (10.9(2)%)	12C
14O	8	6	14.008596706(27)	70.621(11) s	β+	14N	0+
15O	8	7	15.0030656(5)	122.266(43) s	β+	15N	1/2−
16O	8	8	15.994914619257(319)	Stable			0+	[0.99738, 0.99776]
17O	8	9	16.999131755953(692)	Stable			5/2+	[0.000367, 0.000400]
18O	8	10	17.999159612136(690)	Stable			0+	[0.00187, 0.00222][6]
19O	8	11	19.0035780(28)	26.470(6) s	β−	19F	5/2+
20O	8	12	20.0040754(9)	13.51(5) s	β−	20F	0+
21O	8	13	21.008655(13)	3.42(10) s	β−	21F	(5/2+)
					β−n ?	20F ?
22O	8	14	22.009970(60)	2.25(9) s	β− (> 78%)	22F	0+
					β−n (< 22%)	21F
23O	8	15	23.015700(130)	97(8) ms	β− (93(2)%)	23F	1/2+
					β−n (7(2)%)	22F
24O	8	16	24.019860(180)	77.4(4.5) ms	β− (57(4)%)	24F	0+
					β−n (43(4)%)	23F
25O	8	17	25.029340(180)	5.18(35) zs	n	24O	3/2+#
26O	8	18	26.037210(180)	4.2(3.3) ps	2n	24O	0+
27O	8	19	27.047960(540)#	< 260 ns	n ?	26O ?	3/2+#
					2n ?	25O ?
28O	8	20	28.055910(750)#	< 100 ns	2n ?	26O ?	0+
					β− (0%)	28F

Stable isotopes

Late in a massive star's life, ¹⁶O concentrates in the N-shell, ¹⁷O in the H-shell and ¹⁸O in the He-shell. Natural oxygen is made of three stable isotopes, ¹⁶O, ¹⁷O, and ¹⁸O, with ¹⁶O being the most abundant (99.762% natural abundance). Depending on the terrestrial source, the standard atomic weight varies within the range of [15.99903, 15.99977] (the conventional value is 15.999).

¹⁶O has high relative and absolute abundance because it is a principal product of stellar evolution and because it is a primary isotope, meaning it can be made by stars that were initially hydrogen only. Most ¹⁶O is synthesized at the end of the helium fusion process in stars; the triple-alpha process creates ¹²C, which captures an additional ⁴He nucleus to produce ¹⁶O. The neon burning process creates additional ¹⁶O.

Both ¹⁷O and ¹⁸O are secondary isotopes, meaning their synthesis requires seed nuclei. ¹⁷O is primarily made by burning hydrogen into helium in the CNO cycle, making it a common isotope in the hydrogen burning zones of stars. Most ¹⁸O is produced when ¹⁴N (made abundant from CNO burning) captures a ⁴He nucleus, becoming ¹⁸F. This quickly (half life around 110 minutes) beta decays to ¹⁸O making that isotope common in the helium-rich zones of stars. About 10⁹ kelvin is needed to fuse oxygen into sulfur.

An atomic mass of 16 was assigned to oxygen prior to the definition of the unified atomic mass unit based on ¹²C. Since physicists referred to ¹⁶O only, while chemists meant the natural mix of isotopes, this led to slightly different mass scales.

Radioisotopes

Thirteen radioisotopes have been characterized; the most stable are ¹⁵O with half-life 122.266(43) s and ¹⁴O with half-life 70.621(11) s. All remaining radioisotopes have half-lives less than 27 s and most have half-lives less than 0.1 s. ²⁴O has half-life 77.4(4.5) ms. The most common decay mode for isotopes lighter than the stable isotopes is β⁺ decay to nitrogen, and the most common mode after is β⁻ decay to fluorine.

Oxygen-13

Oxygen-13 is an unstable isotope, with 8 protons and 5 neutrons. It has spin 3/2−, and half-life 8.58(5) ms. Its atomic mass is 13.024815(10) Da. It decays to nitrogen-13 by electron capture, with a decay energy of 17.770(10) MeV. Its parent nuclide is fluorine-14.

Oxygen-15

Oxygen-15 is a radioisotope, often used in positron emission tomography (PET). It can be used in, among other things, water for PET myocardial perfusion imaging and for brain imaging. It has an atomic mass of 15.0030656(5), and a half-life of 122.266(43) s. It is produced through deuteron bombardment of nitrogen-14 using a cyclotron.

Oxygen-15 and nitrogen-13 are produced in air when gamma rays (for example from lightning) knock neutrons out of ¹⁶O and ¹⁴N:

¹⁶O + γ → ¹⁵ O + n

¹⁴N + γ → ¹³ N + n

¹⁵O decays to ¹⁵N, emitting a positron. The positron quickly annihilates with an electron, producing two gamma rays of about 511 keV. After a lightning bolt, this gamma radiation dies down with half-life 2 min, but these low-energy gamma rays go on average only about 90 metres through the air. Together with rays produced from positrons from nitrogen-13 they may only be detected for a minute or so as the "cloud" of ¹⁵O and ¹³O floats by, carried by the wind.

Fluorine

Fluorine (₉F) has 18 known isotopes ranging from ¹³F to ³¹F(with the exception of ³⁰F) and two isomers (^18mF and^26mF). Only fluorine-19 is stable and naturally occurring in more than trace quantities; therefore, fluorine is a monoisotopic and mononuclidic element.

The longest-lived radioisotope is ¹⁸F; it has a half-life of 109.734(8) min. All other fluorine isotopes have half-lives of less than a minute, and most of those less than a second. The least stable known isotope is ¹⁴F, whose half-life is 500(60) yoctoseconds, corresponding to a resonance width of 910(100) keV.

List of isotopes

Nuclide	Z	N	Isotopic mass (Da)	Half-life	Decay mode	Daughter isotope	Spin and parity	Natural abundance (mole fraction)
	Excitation energy							Normal proportion	Range of variation
13F	9	4	13.045120(540)#		p ?	12O ?	1/2+#
14F	9	5	14.034320(40)	500(60) ys [910(100) keV]	p ?	13O ?	2−
15F	9	6	15.017785(15)	1.1(3) zs [376 keV]	p	14O	1/2+
16F	9	7	16.011460(6)	21(5) zs [21.3(5.1) keV]	p	15O	0−
17F	9	8	17.00209524(27)	64.370(27) s	β+	17O	5/2+
18F	9	9	18.0009373(5)	109.734(8) min	β+	18O	1+	Trace
18mF	1121.36(15) keV			162(7) ns	IT	18F	5+
19F	9	10	18.998403162067(883)	Stable			1/2+	1
20F	9	11	19.99998125(3)	11.0062(80) s	β−	20Ne	2+
21F	9	12	20.9999489(19)	4.158(20) s	β−	21Ne	5/2+
22F	9	13	22.002999(13)	4.23(4) s	β− (> 89%)	22Ne	(4+)
					β−n (< 11%)	21Ne
23F	9	14	23.003530(40)	2.23(14) s	β− (> 86%)	23Ne	5/2+
					β−n (< 14%)	22Ne
24F	9	15	24.008100(100)	384(16) ms	β− (> 94.1%)	24Ne	3+
					β−n (< 5.9%)	23Ne
25F	9	16	25.012170(100)	80(9) ms	β− (76.9(4.5)%)	25Ne	(5/2+)
					β−n (23.1(4.5)%)	24Ne
					β−2n ?	23Ne ?
26F	9	17	26.020050(110)	8.2(9) ms	β− (86.5(4.0)%)	26Ne	1+
					β−n (13.5(4.0)%)	25Ne
					β−2n ?	24Ne ?
26mF	643.4(1) keV			2.2(1) ms	IT (82(11)%)	26F	(4+)
					β−n (12(8)%)	25Ne
					β− ?	26Ne ?
27F	9	18	27.026980(130)	5.0(2) ms	β−n (77(21)%)	26Ne	5/2+#
					β− (23(21)%)	27Ne
					β−2n ?	25Ne ?
28F	9	19	28.035860(130)	46 zs	n	27F	(4−)
29F	9	20	29.043100(560)	2.5(3) ms	β−n (60(40)%)	28Ne	(5/2+)
					β− (40(40)%)	29Ne
					β−2n ?	27Ne ?
31F	9	22	31.06020(570)#	2 ms# [> 260 ns]	β− ?	31Ne ?	5/2+#
					β−n ?	30Ne ?
					β−2n ?	29Ne ?

Fluorine-18

Of the unstable nuclides of fluorine, ¹⁸F has the longest half-life, 109.734(8) min. It decays to ¹⁸O via β⁺ decay. For this reason ¹⁸F is a commercially important source of positrons. Its major value is in the production of the radiopharmaceutical fludeoxyglucose, used in positron emission tomography in medicine.

Fluorine-18 is the lightest unstable nuclide with equal odd numbers of protons and neutrons, having 9 of each. (See also the "magic numbers" discussion of nuclide stability.)

Fluorine-19

Fluorine-19 is the only stable isotope of fluorine. Its abundance is 100%; no other isotopes of fluorine exist in significant quantities. Its binding energy is 147801.3648(38) keV. Fluorine-19 is NMR-active with a spin of 1/2+, so it is used in fluorine-19 NMR spectroscopy.

Fluorine-20

Fluorine-20 is an unstable isotope of fluorine. It has a half-life of 11.0062(80) s and decays via beta decay to the stable nuclide ²⁰Ne. Its specific radioactivity is 1.8693(14)×10⁺²¹ Bq/g and has a mean lifetime of 15.879(12) s.

Fluorine-21

Fluorine-21, as with fluorine-20, is also an unstable isotope of fluorine. It has a half-life of 4.158(20) s. It undergoes beta decay as well, decaying to ²¹Ne, which is a stable nuclide. Its specific activity is 4.781(23)×10⁺²¹ Bq/g.

Isomers

Only two nuclear isomers (long-lived excited nuclear states), fluorine-18m and fluorine-26m, have been characterized. The half-life of ^18mF before it undergoes isomeric transition is 162(7) nanoseconds.^[4] This is less than the decay half-life of any of the fluorine radioisotope nuclear ground states except for mass numbers 14–16, 28, and 31. ^[9] The half-life of ^26mF is 2.2(1) milliseconds; it decays mainly to its ground state of ²⁶F or (rarely, via beta-minus decay) to one of high excited states of ²⁶Ne with delayed neutron emission.

Neon

Neon (₁₀Ne) possesses three stable isotopes: ²⁰Ne, ²¹Ne, and ²²Ne. In addition, 16 radioactive isotopes have been discovered, ranging from ¹⁵Ne to ³⁴Ne, all short-lived. The longest-lived is ²⁴Ne with a half-life of 3.38(2) min. All others are under a minute, most under a second. The least stable is ¹⁵Ne with a half-life of 770(300) ys (7.7(3.0)×10⁻²² s). See isotopes of carbon for notes about the measurement. Light radioactive neon isotopes usually decay to fluorine or oxygen, while heavier ones decay to sodium.

List of isotopes

Nuclide	Z	N	Isotopic mass (Da)	Half-life [resonance width]	Decay mode	Daughter isotope	Spin and parity	Natural abundance (mole fraction)
	Excitation energy							Normal proportion	Range of variation
15Ne	10	5	15.043170(70)	770(300) ys [590(230) keV]	2p	13O	(3/2−)
16Ne	10	6	16.025751(22)	> 5.7 zs [< 80 keV]	2p	14O	0+
17Ne	10	7	17.0177140(4)	109.2(6) ms	β+p (94.4(2.9)%)	16O	1/2−
					β+α (3.51(1)%)	13N
					β+ (2.1(2.9)%)	17F
					β+pα (0.014(4)%)	12C
18Ne	10	8	18.0057087(4)	1664.20(47) ms	β+	18F	0+
19Ne	10	9	19.00188091(17)	17.2569(19) s	β+	19F	1/2+
20Ne	10	10	19.9924401753(16)	Stable			0+	0.9048(3)	[0.8847, 0.9051]
21Ne	10	11	20.99384669(4)	Stable			3/2+	0.0027(1)	[0.0027, 0.0171]
22Ne	10	12	21.991385114(19)	Stable			0+	0.0925(3)	[0.0920, 0.0996]
23Ne	10	13	22.99446691(11)	37.15(3) s	β−	23Na	5/2+
24Ne	10	14	23.9936106(6)	3.38(2) min	β−	24mNa	0+
25Ne	10	15	24.997810(30)	602(8) ms	β−	25Na	1/2+
26Ne	10	16	26.000516(20)	197(2) ms	β− (99.87(3)%)	26Na	0+
					β−n (0.13(3)%)	25Na
27Ne	10	17	27.007570(100)	30.9(1.1) ms	β− (98.0(5)%)	27Na	(3/2+)
					β−n (2.0(5)%)	26Na
					β−2n ?	25Na ?
28Ne	10	18	28.012130(140)	18.8(2) ms	β− (84.3(1.1)%)	28Na	0+
					β−n (12(1)%)	27Na
					β−2n (3.7(5)%)	26Na
29Ne	10	19	29.019750(160)	14.7(4) ms	β− (68.0(5.1)%)	29Na	(3/2−)
					β−n (28(5)%)	28Na
					β−2n (4(1)%)	27Na
30Ne	10	20	30.024990(270)	7.22(18) ms	β− (78.1(4.6)%)	30Na	0+
					β−n (13(4)%)	29Na
					β−2n (8.9(2.3)%)	28Na
31Ne	10	21	31.033470(290)	3.4(8) ms	β−	31Na	(3/2−)
					β−n ?	30Na ?
					β−2n ?	29Na ?
32Ne	10	22	32.039720(540)#	3.5(9) ms	β−	32Na	0+
					β−n ?	31Na ?
					30Na ?
34Ne	10	24	34.056730(550)#	2 ms# [> 1.5 μs]	β− ?	34Na	0+
					β−2n ?	32Ne ?
					β−n ?	33Ne ?

Sodium

There are 21 isotopes of sodium (₁₁Na), ranging from ¹⁷Na to ³⁹Na, and two isomers (^22mNa and ^24mNa). ²³Na is the only stable (and the only primordial) isotope. It is considered a monoisotopic element and it has standard atomic weight of 22.98976928(2). Sodium has two radioactive cosmogenic isotopes (²²Na, with a half-life of 2.6019(6) years; and ²⁴Na, with a half-life of 14.9560(15) h). With the exception of those two isotopes, all other isotopes have half-lives under a minute, most under a second. The shortest-lived is ¹⁸Na, with a half-life of 1.3(4)×10⁻²¹ seconds. Acute neutron radiation exposure (e.g., from a nuclear criticality accident) converts some of the stable ²³Na in human blood plasma to ²⁴Na. By measuring the concentration of this isotope, the neutron radiation dosage to the victim can be computed. ²²Na is a positron-emitting isotope with a remarkably long half-life. It is used to create test-objects and point-sources for positron emission tomography.

List of isotopes

Nuclide	Z	N	Isotopic mass (Da)	Half-life	Decay mode	Daughter isotope	Spin and parity	Natural abundance (mole fraction)
	Excitation energy							Normal proportion	Range of variation
17Na	11	6	17.037270(60)		p	16Ne	(1/2+)
18Na	11	7	18.02688(10)	1.3(4) zs	p=?	17Ne	1−#
19Na	11	8	19.013880(11)	> 1 as	p	18Ne	(5/2+)
20Na	11	9	20.0073543(12)	447.9(2.3) ms	β+ (75.0(4)%)	20Ne	2+
					β+α (25.0(4)%)	16O
21Na	11	10	20.99765446(5)	22.4550(54) s	β+	21Ne	3/2+
22Na	11	11	21.99443742(18)	2.6019(6) y	β+ (90.57(8)%)	22Ne	3+	Trace
					ε (9.43(6)%)	22Ne
22m1Na	583.05(10) keV			243(2) ns	IT	22Na	1+
22m2Na	657.00(14) keV			19.6(7) ps	IT	22Na	0+
23Na	11	12	22.9897692820(19)	Stable			3/2+	1
24Na	11	13	23.990963012(18)	14.9560(15) h	β−	24Mg	4+	Trace
24mNa	472.2074(8) keV			20.18(10) ms	IT (99.95%)	24Na	1+
					β− (0.05%)	24Mg
25Na	11	14	24.9899540(13)	59.1(6) s	β−	25Mg	5/2+
26Na	11	15	25.992635(4)	1.07128(25) s	β−	26Mg	3+
26mNa	82.4(4) keV			4.35(16) μs	IT	26Na	1+
27Na	11	16	26.994076(4)	301(6) ms	β− (99.902(24)%)	27Mg	5/2+
					β−n (0.098(24)%)	26Mg
28Na	11	17	27.998939(11)	33.1(1.3) ms	β− (99.42(12)%)	28Mg	1+
					β−n (0.58(12)%)	27Mg
29Na	11	18	29.002877(8)	43.2(4) ms	β− (78%)	29Mg	3/2+
					β−n (22(3)%)	28Mg
					β−2n ?	27Mg ?
30Na	11	19	30.009098(5)	45.9(7) ms	β− (70.2(2.2)%)	30Mg	2+
					β−n (28.6(2.2)%)	29Mg
					β−2n (1.24(19)%)	28Mg
					β−α (5.5(2)%×10−5)	26Ne
31Na	11	20	31.013147(15)	16.8(3) ms	β− (> 63.2(3.5)%)	31Mg	3/2+
					β−n (36.0(3.5)%)	30Mg
					β−2n (0.73(9)%)	29Mg
					β−3n (< 0.05%)	28Mg
32Na	11	21	32.020010(40)	12.9(3) ms	β− (66.4(6.2)%)	32Mg	(3−)
					β−n (26(6)%)	31Mg
					β−2n (7.6(1.5)%)	30Mg
33Na	11	22	33.02553(48)	8.2(4) ms	β−n (47(6)%)	32Mg	(3/2+)
					β− (40.0(6.7)%)	33Mg
					β−2n (13(3)%)	31Mg
34Na	11	23	34.03401(64)	5.5(1.0) ms	β−2n (~50%)	32Mg	1+
					β− (~35%)	34Mg
					β−n (~15%)	33Mg
35Na	11	24	35.04061(72)#	1.5(5) ms	β−	35Mg	3/2+#
					β−n ?	34Mg ?
					β−2n ?	33Mg ?
37Na	11	26	37.05704(74)#	1# ms [> 1.5 μs]	β− ?	37Mg ?	3/2+#
					β−n ?	36Mg ?
					β−2n ?	35Mg ?
39Na [3]	11	28	39.07512(80)#	1# ms [> 400 ns]	β− ?	39Mg ?	3/2+#
					β−n ?	38Mg ?
					β−2n ?	37Mg ?

Sodium-22

Sodium-22 is a radioactive isotope of sodium, undergoing positron emission to ²²Ne with a half-life of 2.6019(6) years. ²²Na is being investigated as an efficient generator of "cold positrons" (antimatter) to produce muons for catalyzing fusion of deuterium. It is also commonly used as a positron source in positron annihilation spectroscopy.

Sodium-24

Sodium-24 is radioactive and can be created from common sodium-23 by neutron activation. With a half-life of 14.9560(15) h, ²⁴Na decays to ²⁴Mg by emission of an electron and two gamma rays. Exposure of the human body to intense neutron radiation creates ²⁴Na in the blood plasma. Measurements of its quantity can be done to determine the absorbed radiation dose of a patient. This can be used to determine the type of medical treatment required. When sodium is used as coolant in fast breeder reactors, ²⁴Na is created, which makes the coolant radioactive. When the ²⁴Na decays, it causes a buildup of magnesium in the coolant. Since the half-life is short, the ²⁴

Na portion of the coolant ceases to be radioactive within a few days after removal from the reactor. Leakage of the hot sodium from the primary loop may cause radioactive fires, as it can ignite in contact with air (and explodes in contact with water). For this reason the primary cooling loop is within a containment vessel.

Sodium has been proposed as a casing for a salted bomb, as it would convert to ²⁴Na and produce intense gamma-ray emissions for a few days.