Isotopes of sodium

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.

Isotopes of sodium (₁₁Na)

Main isotopes[1] Decay abun­dance half-life (t1/2) mode pro­duct 22Na trace 2.6019 y β+ 22Ne 23Na 100% stable 24Na trace 14.956 h β− 24Mg
Standard atomic weight Ar°(Na)
	22.98976928±0.00000002[2] 22.990±0.001 (abridged)[3]
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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.

List of isotopes

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: view

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. # – 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. Cosmogenic nuclide

Sodium-22

Disk containing 1 μCi of sodium-22

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

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]

Sodium-24

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]

See also

Daughter products other than sodium

• Isotopes of magnesium
• Isotopes of neon
• Isotopes of oxygen

Notes

1. 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