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| Standard atomic weight Ar°(Na) | ||||||||||||||||||||||||||
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There are 20 isotopes of sodium (11Na), ranging from 17
Nato39
Na (except for the still-unknown 36Na and 38Na),[4] and two isomers (22m
Na and 24m
Na). 23
Na is the only stable (and the only primordial) isotope. It is considered a monoisotopic element and it has a standard atomic weightof22.98976928(2). Sodium has two radioactive cosmogenic isotopes (22
Na, with a half-lifeof2.6019(6) years;[nb 1] 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 17Na 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.
| Nuclide [n 1] |
Z | N | Isotopic mass (Da)[5] [n 2][n 3] |
Half-life[1] [n 4] |
Decay mode[1] [n 5] |
Daughter isotope [n 6] |
Spin and parity[1] [n 7][n 4] |
Isotopic abundance | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Excitation energy | |||||||||||||||||||
| 17 Na |
11 | 6 | 17.037270(60) | p | 16 Ne |
(1/2+) | |||||||||||||
| 18 Na |
11 | 7 | 18.02688(10) | 1.3(4) zs | p=?[n 8] | 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+ | ||||||||||||
| β+α (25.0(4)%) | 16 O | ||||||||||||||||||
| 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[nb 1] | β+ (90.57(8)%) | 22 Ne |
3+ | Trace[n 9] | |||||||||||
| ε (9.43(6)%) | 22 Ne | ||||||||||||||||||
| 22m1 Na |
583.05(10) keV | 243(2) ns | IT | 22 Na |
1+ | ||||||||||||||
| 22m2 Na |
657.00(14) keV | 19.6(7) ps | IT | 22 Na |
0+ | ||||||||||||||
| 23 Na |
11 | 12 | 22.9897692820(19) | Stable | 3/2+ | 1 | |||||||||||||
| 24 Na |
11 | 13 | 23.990963012(18) | 14.9560(15) h | β− | 24 Mg |
4+ | Trace[n 9] | |||||||||||
| 24m Na |
472.2074(8) keV | 20.18(10) ms | IT (99.95%) | 24 Na |
1+ | ||||||||||||||
| β− (0.05%) | 24 Mg | ||||||||||||||||||
| 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 | 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+ | ||||||||||||
| β−n (0.098(24)%) | 26 Mg | ||||||||||||||||||
| 28 Na |
11 | 17 | 27.998939(11) | 33.1(1.3) ms | β− (99.42(12)%) | 28 Mg |
1+ | ||||||||||||
| β−n (0.58(12)%) | 27 Mg | ||||||||||||||||||
| 29 Na |
11 | 18 | 29.002877(8) | 43.2(4) ms | β− (78%) | 29 Mg |
3/2+ | ||||||||||||
| β−n (22(3)%) | 28 Mg | ||||||||||||||||||
| β−2n ?[n 10] | 27 Mg ? | ||||||||||||||||||
| 30 Na |
11 | 19 | 30.009098(5) | 45.9(7) ms | β− (70.2(2.2)%) | 30 Mg |
2+ | ||||||||||||
| β−n (28.6(2.2)%) | 29 Mg | ||||||||||||||||||
| β−2n (1.24(19)%) | 28 Mg | ||||||||||||||||||
| β−α (5.5(2)%×10−5) | 26 Ne | ||||||||||||||||||
| 31 Na |
11 | 20 | 31.013147(15) | 16.8(3) ms | β− (> 63.2(3.5)%) | 31 Mg |
3/2+ | ||||||||||||
| β−n (36.0(3.5)%) | 30 Mg | ||||||||||||||||||
| β−2n (0.73(9)%) | 29 Mg | ||||||||||||||||||
| β−3n (< 0.05%) | 28 Mg | ||||||||||||||||||
| 32 Na |
11 | 21 | 32.020010(40) | 12.9(3) ms | β− (66.4(6.2)%) | 32 Mg |
(3−) | ||||||||||||
| β−n (26(6)%) | 31 Mg | ||||||||||||||||||
| β−2n (7.6(1.5)%) | 30 Mg | ||||||||||||||||||
| 33 Na |
11 | 22 | 33.02553(48) | 8.2(4) ms | β−n (47(6)%) | 32 Mg |
(3/2+) | ||||||||||||
| β− (40.0(6.7)%) | 33 Mg | ||||||||||||||||||
| β−2n (13(3)%) | 31 Mg | ||||||||||||||||||
| 34 Na |
11 | 23 | 34.03401(64) | 5.5(1.0) ms | β−2n (~50%) | 32 Mg |
1+ | ||||||||||||
| β− (~35%) | 34 Mg | ||||||||||||||||||
| β−n (~15%) | 33 Mg | ||||||||||||||||||
| 35 Na |
11 | 24 | 35.04061(72)# | 1.5(5) ms | β− | 35 Mg |
3/2+# | ||||||||||||
| β−n ?[n 10] | 34 Mg ? | ||||||||||||||||||
| β−2n ?[n 10] | 33 Mg ? | ||||||||||||||||||
| 37 Na |
11 | 26 | 37.05704(74)# | 1# ms [> 1.5 μs] | β− ?[n 10] | 37 Mg ? |
3/2+# | ||||||||||||
| β−n ?[n 10] | 36 Mg ? | ||||||||||||||||||
| β−2n ?[n 10] | 35 Mg ? | ||||||||||||||||||
| 39 Na [4] |
11 | 28 | 39.07512(80)# | 1# ms [> 400 ns] | β− ?[n 10] | 39 Mg ? |
3/2+# | ||||||||||||
| β−n ?[n 10] | 38 Mg ? | ||||||||||||||||||
| β−2n ?[n 10] | 37 Mg ? | ||||||||||||||||||
| This table header & footer: | |||||||||||||||||||
| IT: | Isomeric transition |
| n: | Neutron emission |
| p: | Proton emission |
Sodium-22 is a radioactive isotope of sodium, undergoing positron emissionto22
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.[citation needed] It is also commonly used as a positron source in positron annihilation spectroscopy.[6]
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.[7] Sodium-23 relaxation has applications in studying cation-biomolecule interactions, intracellular and extracellular sodium, ion transport in batteries, and quantum information processing.[8]
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.[9][10]
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.[10] 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,[11] 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.[12][13]
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Isotopes of the chemical elements
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