Isotopes of sodium

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Main isotopes of sodium (11Na)
Iso­tope Decay
abun­dance half-life (t1/2) mode pro­duct
22Na trace 2.6019(6) y β+ (90.57(8)%) 22Ne
ε (9.43(6)%) 22Ne
23Na 100% stable
24Na trace 14.9560(15) h β− 24Mg
Standard atomic weight Ar°(Na)
  • 22.98976928±0.00000002
  • 22.990±0.001 (abridged)[1][2]

There are 22 isotopes of sodium (11Na), ranging from 17
Na to 39
Na,[3] 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 weight of 22.98976928(2). Sodium has two radioactive cosmogenic isotopes (22
Na, with a half-life of 2.6019(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 18
Na, 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 23
Na 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[4]
[n 1] 		Z N Isotopic mass (Da)[5]
[n 2][n 3] 		Half-life
[n 4] 		Decay
mode
[n 5] 		Daughter
isotope
[n 6] 		Spin and
parity
[n 7][n 4] 		Natural abundance (mole fraction)
Excitation energy Normal proportion Range of variation
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] e+ (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
 ?
36
Na
 		11 25 36.04928(74)# < 180 ns n ?[n 10] 35
Na
 ?
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
 ?
38
Na
 		11 27 38.06646(77)# < 400 ns n ?[n 10] 37
Na
 ?
39
Na
[3] 		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:
  1. ^ mNa – Excited nuclear isomer.
  2. ^ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
  3. ^ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
  4. ^ a b # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  5. ^ Modes of decay:
    IT: Isomeric transition
    n: Neutron emission
    p: Proton emission
  6. ^ Bold symbol as daughter – Daughter product is stable.
  7. ^ ( ) spin value – Indicates spin with weak assignment arguments.
  8. ^ Decay mode shown has been observed, but its intensity is not known experimentally.
  9. ^ a b Cosmogenic nuclide
  10. ^ a b c d e f g h i j k 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.[6]

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.[7][8]

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.[8] 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,[9] 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.[10][11]

Notes

  1. ^ a b Note that NUBASE2020 uses the tropical year to convert between years and other units of time, not the Gregorian year. The relationship between years and other time units in NUBASE2020 is as follows: 1 y = 365.2422 d = 31 556 926 s

References

  1. ^ "Standard Atomic Weights: Sodium". CIAAW. 2005.
  2. ^ Meija, Juris; et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry. 88 (3): 265–91. doi:10.1515/pac-2015-0305.
  3. ^ a b Ahn, D.S.; et al. (2018). New isotope of 39Na and the neutron dripline of neon isotopes using a 345 MeV/nucleon 48Ca beam (PDF) (Report). RIKEN Accelerator Progress Reports. Vol. 51. p. 82.
  4. ^ Half-life, decay mode, nuclear spin, and isotopic composition is sourced in:
    Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
  5. ^ Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3): 030003. doi:10.1088/1674-1137/abddaf.
  6. ^ Saro, Matúš; Kršjak, Vladimír; Petriska, Martin; Slugeň, Vladimír (2019-07-29). "Sodium-22 source contribution determination in positron annihilation measurements using GEANT4". AIP Conference Proceedings. 2131 (1): 020039. doi:10.1063/1.5119492. ISSN 0094-243X.
  7. ^ "sodium-24". Encyclopædia Britannica.
  8. ^ a b Ekendahl, Daniela; Rubovič, Peter; Žlebčík, Pavel; Hupka, Ivan; Huml, Ondřej; Bečková, Věra; Malá, Helena (7 November 2019). "Neutron dose assessment using samples of human blood and hair". Radiation Protection Dosimetry. 186 (2–3): 202–205. doi:10.1093/rpd/ncz202.
  9. ^ Unusual occurrences during LMFR operation, Proceedings of a Technical Committee meeting held in Vienna, 9–13 November 1998, IAEA. Pages 84, 122.
  10. ^ "Science: fy for Doomsday". Time. November 24, 1961. Archived from the original on March 14, 2016.
  11. ^ Clark, W. H. (1961). "Chemical and Thermonuclear Explosives". Bulletin of the Atomic Scientists. 17 (9): 356–360. doi:10.1080/00963402.1961.11454268.

External links

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