Isotopes of sodium

Main isotopes of sodium (11Na)
Iso­tope Decay
abun­dance half-life (t1/2) mode pro­duct
22Na trace 2.602 y β+ 22Ne
23Na 100% stable
24Na trace 14.96 h β− 24Mg
Standard atomic weight (Ar, standard)
  • 22.98976928(2)[1]

There are twenty recognized isotopes of sodium (11Na), ranging from 18
Na to 37
Na and two isomers (22m
Na and 24m
Na). 23
Na is the only stable (and the only primordial) isotope. As such, 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, half-life = 2.605 years; and 24
Na, half-life ≈ 15 hours). With the exception of those two, 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
symbol		 Z(p) N(n)  
isotopic mass (u)
 		 half-life decay
mode(s)[2][n 1]		 daughter
isotope(s)[n 2]		 nuclear
spin and
parity		 representative
isotopic
composition
(mole fraction)		 range of natural
variation
(mole fraction)
excitation energy
18Na 11 7 18.02597(5) 1.3(4)×10−21 s p (>99.9%) 17Ne (1−)#
β+ (<.1%) 18Ne
19Na 11 8 19.013877(13) <40 ns p 18Ne (5/2+)#
20Na 11 9 20.007351(7) 447.9(23) ms β+ (75%) 20Ne 2+
β+, α (25%) 16O
21Na 11 10 20.9976552(8) 22.49(4) s β+ 21Ne 3/2+
22Na 11 11 21.9944364(4) 2.6027(10) y β+ 22Ne 3+ Trace[n 3]
22mNa 583.03(9) keV 244(6) ns 1+
23Na 11 12 22.9897692809(29) Stable 3/2+ 1.0000
24Na 11 13 23.99096278(8) 14.9590(12) h β− 24Mg 4+ Trace[n 3]
24mNa 472.207(9) keV 20.20(7) ms IT (99.95%) 24Na 1+
β− (.05%) 24Mg
25Na 11 14 24.9899540(13) 59.1(6) s β− 25Mg 5/2+
26Na 11 15 25.992633(6) 1.077(5) s β− 26Mg 3+
27Na 11 16 26.994077(4) 301(6) ms β− (99.87%) 27Mg 5/2+
β−, n (.13%) 26Mg
28Na 11 17 27.998938(14) 30.5(4) ms β− (99.421%) 28Mg 1+
β−, n (.579%) 27Mg
29Na 11 18 29.002861(14) 44.9(12) ms β− (74.09%) 29Mg 3/2(+#)
β−, n (25.91%) 28Mg
30Na 11 19 30.008976(27) 48.4(17) ms β− (68.83%) 30Mg 2+
β−, n (30.0%) 29Mg
β−, 2n (1.17%) 28Mg
β−, α 26Ne
31Na 11 20 31.01359(23) 17.0(4) ms β− (62.05%) 31Mg (3/2+)
β−, n 30Mg
β−, 2n 29Mg
β−, 3n 28Mg
32Na 11 21 32.02047(38) 12.9(7) ms β− 32Mg (3−,4−)
β−, n 31Mg
β−, 2n 30Mg
33Na 11 22 33.02672(94) 8.2(2) ms β−, n (52.0%) 32Mg 3/2+#
β− (36.0%) 33Mg
β−, 2n (12.0%) 31Mg
34Na 11 23 34.03517(96)# 5.5(10) ms β−, 2n (50.0%) 32Mg 1+
β− (35.0%) 34Mg
β−, n (15.0%) 33Mg
35Na 11 24 35.04249(102)# 1.5(5) ms β− (>99.9%) 35Mg 3/2+#
β−, n (<.1%) 34Mg
36Na 11 25 36.05148(102)# <260 ns
37Na 11 26 37.05934(103)# 1# ms [>1.5 µs] 3/2+#
  1. ↑ Abbreviations:
    IT: Isomeric transition
  2. ↑ Bold for stable isotopes
  3. 1 2 Cosmogenic nuclide

Notes

  • Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
  • Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC, which use expanded uncertainties.

Sodium-24

Sodium-24 is one of the most important isotopes. It is radioactive and created from common sodium-23 by neutron bombardment. With a 15-hour half life, 24
Na decays to 24
Mg by emission of an electron and two gamma rays. Exposure of the human body to intense neutron flux creates 24
Na in blood plasma. Measurements of its quantity are used to determine the absorbed radiation dose of the patient. This is used to determine the level of medical treatment required.

When the sodium-potassium alloy is used as a coolant in nuclear 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.

Lighter:
sodium-23		 Isotopes of sodium is an
isotope of sodium		 Heavier:
sodium-25
Decay product of:
neon-24		 Decay chain
of isotopes of sodium		 Decays to:
magnesium-24

Sodium-22

Sodium-22 is being investigated as an efficient generator of “cold positrons” (antimatter) to produce muons for catalyzing fusion of deuterium.

References

  • Isotope masses from:
    • G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A. 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001. Archived from the original (PDF) on 2008-09-23.
  • Isotopic compositions and standard atomic masses from:
    • J. R. de Laeter; J. K. Böhlke; P. De Bièvre; H. Hidaka; H. S. Peiser; K. J. R. Rosman; P. D. P. Taylor (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.
    • M. E. Wieser (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051. Lay summary.
  • Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.
    • G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A. 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001. Archived from the original (PDF) on 2008-09-23.
    • National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. Retrieved September 2005. Check date values in: |accessdate= (help)
    • N. E. Holden (2004). "Table of the Isotopes". In D. R. Lide. CRC Handbook of Chemistry and Physics (85th ed.). CRC Press. Section 11. ISBN 978-0-8493-0485-9.
  • Sodium-22 as fusion initiator:
    • Brian Wang. "Positron Dynamics near term work to proving out antimatter catalyzed deuterium fusion propulsion with over 100,000 ISP". NextBig Future. Retrieved October 25, 2016.


  1. ↑ Meija, J.; 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.
  2. ↑ "Universal Nuclide Chart". nucleonica. (Registration required (help)).
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