Isotopes of sodium

There are twenty recognized isotopes of sodium, 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 relative atomic mass: 22.98976928(2). Sodium has two radioactive cosmogenic isotopes (05 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.

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	decay mode(s)[1][n 1]	daughter isotope(s)[n 2]	nuclear spin	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. 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.

References

• Isotope masses from:
  • G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and 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.
• 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 and 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.
  • National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. Retrieved September 2005.
  • 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.

External links

• Sodium isotopes data from The Berkeley Laboratory Isotopes Project's

1. "Universal Nuclide Chart". nucleonica. (registration required (help)).