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Standard atomic weight Ar°(Na) | ||||||||||||||||||||||||||
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There are 20 known isotopes of sodium (11Na), ranging from 17
Na to 39
Na (except for 36Na and 38Na), [4] and five isomers. 23
Na is the only stable (and the only primordial) isotope. It is considered a monoisotopic element and it has a standard atomic weight given by that isotope. Sodium has two radioactive cosmogenic isotopes (22
Na, with a half-life of 2.6019 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.
Acute neutron radiation exposure (e.g., from a nuclear criticality accident) converts some of the stable 23
Na in human blood plasma to 24
Na. The neutron radiation dosage to the victim can be assessed thus by prompt measurement of the radioisotope.
22
Na is a positron-emitting isotope with a relatively long half-life, about 2.6 years. 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 | 21.99443755(14) | 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 ? | 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 | ||||||||||||||||||
32m Na [6] | 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+) | ||||||||||||
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 ? | 34 Mg ? | ||||||||||||||||||
β−2n ? | 33 Mg ? | ||||||||||||||||||
37 Na | 11 | 26 | 37.05704(74)# | 1# ms [> 1.5 μs] | β− ? | 37 Mg ? | 3/2+# | ||||||||||||
β−n ? | 36 Mg ? | ||||||||||||||||||
β−2n ? | 35 Mg ? | ||||||||||||||||||
39 Na [4] | 11 | 28 | 39.07512(80)# | 1# ms [> 400 ns] | β− ? | 39 Mg ? | 3/2+# | ||||||||||||
β−n ? | 38 Mg ? | ||||||||||||||||||
β−2n ? | 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 emission to 22
Ne with a half-life of 2.6019 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. [7]
Sodium-23 is the sole natural isotope of sodium, with an atomic mass of 22.98976928. Because of this, sodium-23 is used in nuclear magnetic resonance in various research fields, including materials science and battery research. [8] Sodium-23 relaxation has applications in studying cation-biomolecule interactions, intracellular and extracellular sodium, ion transport in batteries, and quantum information processing. [9]
Radioactive sodium-24 is radioactive and generally created from common sodium-23 by neutron activation. With a half-life of 14.956 hours, 24
Na decays to 24
Mg by emission of an electron and, almost always, two gamma rays. [10] [11]
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. [11] This can be used to determine the medical treatment required.
When sodium is used as coolant in fast breeder reactors, 24
Na is created within it, and it becomes radioactive. When the 24
Na decays, it causes formation of magnesium in the coolant, which must be removed. 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, [12] as it can ignite in contact with air (and explodes in contact with water). For this reason, the primary cooling loop is placed within the 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. [13] [14]
Daughter products other than sodium