# Isotopes of sodium

There are 20 isotopes of sodium ($_{11}$Na), ranging from $^{17}$ Na to $^{39}$ Na (except for the still-unknown $^{36}$Na and $^{38}$Na), and five isomers (two for $^{22}$ Na, and one each for $^{24}$ Na, $^{26}$ Na, and $^{32}$ Na). $^{23}$ Na is the only stable (and the only primordial) isotope. It is considered a monoisotopic element and it has a standard atomic weight of 22.98976928(2). Sodium has two radioactive cosmogenic isotopes ($^{22}$ Na, with a half-life of 2.6019(6) years; and $^{24}$ Na, 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 the unbound $^{18}$ Na, with a half-life of 1.3(4)×10$^{−21}$ seconds (although the half-life of the similarly unbound $^{17}$Na is not measured).
Acute neutron radiation exposure (e.g., from a nuclear criticality accident) converts some of the stable $^{23}$ Na (in the form of Na$^+$ ion) in human blood plasma to $^{24}$ Na. By measuring the concentration of this isotope, the neutron radiation dosage to the victim can be computed.
$^{22}$ Na 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 | Isotopic abundance |
| Isotopic abundance |||
| $^{17}$ Na | 11 | 6 | 17.037270(60) | | p | $^{16}$ Ne | (1/2+) | |
| $^{18}$ Na | 11 | 7 | 18.02688(10) | 1.3(4) zs | p ? | $^{17}$ Ne | 1−# | |
| $^{19}$ Na | 11 | 8 | 19.013880(11) | > 1 as | p | $^{18}$ Ne | (5/2+) | |
| $^{20}$ Na | 11 | 9 | 20.0073543(12) | 447.9(2.3) ms | β$^+$ (75.0(4)%) | $^{20}$ Ne | 2+ | |
| $^{20}$ Na | 11 | 9 | 20.0073543(12) | 447.9(2.3) ms | β$^+$α (25.0(4)%) | $^{16}$ O | 2+ | |
| $^{21}$ Na | 11 | 10 | 20.99765446(5) | 22.4550(54) s | β$^+$ | $^{21}$ Ne | 3/2+ | |
| $^{22}$ Na | 11 | 11 | 21.99443742(18) | 2.6019(6) y | β$^+$ (90.57(8)%) | $^{22}$ Ne | 3+ | Trace |
| $^{22}$ Na | 11 | 11 | 21.99443742(18) | 2.6019(6) y | ε (9.43(6)%) | $^{22}$ Ne | 3+ | Trace |
| $^{22m1}$ Na | 583.05(10) keV | 583.05(10) keV | 583.05(10) keV | 243(2) ns | IT | $^{22}$ Na | 1+ | |
| $^{22m2}$ Na | 657.00(14) keV | 657.00(14) keV | 657.00(14) keV | 19.6(7) ps | IT | $^{22}$ Na | 0+ | |
| $^{23}$ Na | 11 | 12 | 22.9897692820(19) | Stable | Stable | Stable | 3/2+ | 1 |
| $^{24}$ Na | 11 | 13 | 23.990963012(18) | 14.9560(15) h | β$^−$ | $^{24}$ Mg | 4+ | Trace |
| $^{24m}$ Na | 472.2074(8) keV | 472.2074(8) keV | 472.2074(8) keV | 20.18(10) ms | IT (99.95%) | $^{24}$ Na | 1+ | |
| $^{24m}$ Na | 472.2074(8) keV | 472.2074(8) keV | 472.2074(8) keV | 20.18(10) ms | β$^−$ (0.05%) | $^{24}$ Mg | 1+ | |
| $^{25}$ Na | 11 | 14 | 24.9899540(13) | 59.1(6) s | β$^−$ | $^{25}$ Mg | 5/2+ | |
| $^{26}$ Na | 11 | 15 | 25.992635(4) | 1.07128(25) s | β$^−$ | $^{26}$ Mg | 3+ | |
| $^{26m}$ Na | 82.4(4) keV | 82.4(4) keV | 82.4(4) keV | 4.35(16) μs | IT | $^{26}$ Na | 1+ | |
| $^{27}$ Na | 11 | 16 | 26.994076(4) | 301(6) ms | β$^−$ (99.902(24)%) | $^{27}$ Mg | 5/2+ | |
| $^{27}$ Na | 11 | 16 | 26.994076(4) | 301(6) ms | β$^−$n (0.098(24)%) | $^{26}$ Mg | 5/2+ | |
| $^{28}$ Na | 11 | 17 | 27.998939(11) | 33.1(1.3) ms | β$^−$ (99.42(12)%) | $^{28}$ Mg | 1+ | |
| $^{28}$ Na | 11 | 17 | 27.998939(11) | 33.1(1.3) ms | β$^−$n (0.58(12)%) | $^{27}$ Mg | 1+ | |
| $^{29}$ Na | 11 | 18 | 29.002877(8) | 43.2(4) ms | β$^−$ (78%) | $^{29}$ Mg | 3/2+ | |
| $^{29}$ Na | 11 | 18 | 29.002877(8) | 43.2(4) ms | β$^−$n (22(3)%) | $^{28}$ Mg | 3/2+ | |
| $^{29}$ Na | 11 | 18 | 29.002877(8) | 43.2(4) ms | β$^−$2n ? | $^{27}$ Mg ? | 3/2+ | |
| $^{30}$ Na | 11 | 19 | 30.009098(5) | 45.9(7) ms | β$^−$ (70.2(2.2)%) | $^{30}$ Mg | 2+ | |
| $^{30}$ Na | 11 | 19 | 30.009098(5) | 45.9(7) ms | β$^−$n (28.6(2.2)%) | $^{29}$ Mg | 2+ | |
| $^{30}$ Na | 11 | 19 | 30.009098(5) | 45.9(7) ms | β$^−$2n (1.24(19)%) | $^{28}$ Mg | 2+ | |
| $^{30}$ Na | 11 | 19 | 30.009098(5) | 45.9(7) ms | β$^−$α (5.5(2)%×10$^{−5}$) | $^{26}$ Ne | 2+ | |
| $^{31}$ Na | 11 | 20 | 31.013147(15) | 16.8(3) ms | β$^−$ (> 63.2(3.5)%) | $^{31}$ Mg | 3/2+ | |
| $^{31}$ Na | 11 | 20 | 31.013147(15) | 16.8(3) ms | β$^−$n (36.0(3.5)%) | $^{30}$ Mg | 3/2+ | |
| $^{31}$ Na | 11 | 20 | 31.013147(15) | 16.8(3) ms | β$^−$2n (0.73(9)%) | $^{29}$ Mg | 3/2+ | |
| $^{31}$ Na | 11 | 20 | 31.013147(15) | 16.8(3) ms | β$^−$3n (< 0.05%) | $^{28}$ Mg | 3/2+ | |
| $^{32}$ Na | 11 | 21 | 32.020010(40) | 12.9(3) ms | β$^−$ (66.4(6.2)%) | $^{32}$ Mg | (3−) | |
| $^{32}$ Na | 11 | 21 | 32.020010(40) | 12.9(3) ms | β$^−$n (26(6)%) | $^{31}$ Mg | (3−) | |
| $^{32}$ Na | 11 | 21 | 32.020010(40) | 12.9(3) ms | β$^−$2n (7.6(1.5)%) | $^{30}$ Mg | (3−) | |
| $^{32m}$ Na | 625 keV | 625 keV | 625 keV | 24(2) μs | IT | $^{32}$ Na | (0+,6−) | |
| $^{33}$ Na | 11 | 22 | 33.02553(48) | 8.2(4) ms | β$^−$n (47(6)%) | $^{32}$ Mg | (3/2+) | |
| $^{33}$ Na | 11 | 22 | 33.02553(48) | 8.2(4) ms | β$^−$ (40.0(6.7)%) | $^{33}$ Mg | (3/2+) | |
| $^{33}$ Na | 11 | 22 | 33.02553(48) | 8.2(4) ms | β$^−$2n (13(3)%) | $^{31}$ Mg | (3/2+) | |
| $^{34}$ Na | 11 | 23 | 34.03401(64) | 5.5(1.0) ms | β$^−$2n (~50%) | $^{32}$ Mg | 1+ | |
| $^{34}$ Na | 11 | 23 | 34.03401(64) | 5.5(1.0) ms | β$^−$ (~35%) | $^{34}$ Mg | 1+ | |
| $^{34}$ Na | 11 | 23 | 34.03401(64) | 5.5(1.0) ms | β$^−$n (~15%) | $^{33}$ Mg | 1+ | |
| $^{35}$ Na | 11 | 24 | 35.04061(72)# | 1.5(5) ms | β$^−$ | $^{35}$ Mg | 3/2+# | |
| $^{35}$ Na | 11 | 24 | 35.04061(72)# | 1.5(5) ms | β$^−$n ? | $^{34}$ Mg ? | 3/2+# | |
| $^{35}$ Na | 11 | 24 | 35.04061(72)# | 1.5(5) ms | β$^−$2n ? | $^{33}$ Mg ? | 3/2+# | |
| $^{37}$ Na | 11 | 26 | 37.05704(74)# | 1# ms [> 1.5 μs] | β$^−$ ? | $^{37}$ Mg ? | 3/2+# | |
| $^{37}$ Na | 11 | 26 | 37.05704(74)# | 1# ms [> 1.5 μs] | β$^−$n ? | $^{36}$ Mg ? | 3/2+# | |
| $^{37}$ Na | 11 | 26 | 37.05704(74)# | 1# ms [> 1.5 μs] | β$^−$2n ? | $^{35}$ Mg ? | 3/2+# | |
| $^{39}$ Na | 11 | 28 | 39.07512(80)# | 1# ms [> 400 ns] | β$^−$ ? | $^{39}$ Mg ? | 3/2+# | |
| $^{39}$ Na | 11 | 28 | 39.07512(80)# | 1# ms [> 400 ns] | β$^−$n ? | $^{38}$ Mg ? | 3/2+# | |
| $^{39}$ Na | 11 | 28 | 39.07512(80)# | 1# ms [> 400 ns] | β$^−$2n ? | $^{37}$ Mg ? | 3/2+# | |
| This table header & footer: view |||||||||
* ↑ $^m$Na – Excited nuclear isomer.
* ↑ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
* ↑ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
* 1 2 # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
* ↑ Modes of decay: IT:Isomeric transition n:Neutron emission p:Proton emission
* ↑ Bold symbol as daughter – Daughter product is stable.
* ↑ ( ) spin value – Indicates spin with weak assignment arguments.
* ↑ Decay mode shown has been observed, but its intensity is not known experimentally.
* 1 2 Cosmogenic nuclide
* 1 2 3 4 5 6 7 8 9 Decay mode shown is energetically allowed, but has not been experimentally observed to occur in this nuclide.

## Sodium-22

Sodium-22 is a radioactive isotope of sodium, undergoing positron emission to $^{22}$ Ne with a half-life of 2.6019(6) years. $^{22}$ Na 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-23

Sodium-23 is an isotope of sodium with an atomic mass of 22.98976928. It is the only stable isotope of sodium and also the only primordial isotope. Because of its abundance, sodium-23 is used in nuclear magnetic resonance in various research fields, including materials science and battery research. Sodium-23 relaxation has applications in studying cation-biomolecule interactions, intracellular and extracellular sodium, ion transport in batteries, and quantum information processing.

## 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, $^{24}$ Na decays to $^{24}$ Mg by emission of an electron and two gamma rays.
Exposure of the human body to intense neutron radiation creates $^{24}$ Na 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, $^{24}$ Na is created, which makes the coolant radioactive. When the $^{24}$ Na 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 $^{24}$ Na and produce intense gamma-ray emissions for a few days.