Isotopes of sodium

There are 20 isotopes of sodium (11Na), ranging from to  (except for the still-unknown 36Na and 38Na), and two isomers ( and ). is the only stable (and the only primordial) isotope. It is considered a monoisotopic element and it has a standard atomic weight of $22.99$. Sodium has two radioactive cosmogenic isotopes (, with a half-life of $2.602 years$; and, with a half-life of $14.956 hours$). With the exception of those two isotopes, all other isotopes have half-lives under a minute, most under a second. The shortest-lived is the unbound, with a half-life of $1.3$ seconds (although the half-life of the similarly unbound 17Na is not measured).

Acute neutron radiation exposure (e.g., from a nuclear criticality accident) converts some of the stable (in the form of Na+ ion) in human blood plasma to. By measuring the concentration of this isotope, the neutron radiation dosage to the victim can be computed.

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

 * 17Sodium
 * style="text-align:right" | 11
 * style="text-align:right" | 6
 * p
 * 16Neon
 * (1/2+)
 * 18Sodium
 * style="text-align:right" | 11
 * style="text-align:right" | 7
 * p=?
 * 17Neon
 * 1−#
 * 19Sodium
 * style="text-align:right" | 11
 * style="text-align:right" | 8
 * p
 * 18Neon
 * (5/2+)
 * rowspan=2|20Sodium
 * rowspan=2 style="text-align:right" | 11
 * rowspan=2 style="text-align:right" | 9
 * rowspan=2|$17.037$
 * rowspan=2|$18.027$
 * β+ ($1.3 zs$)
 * 20Neon
 * rowspan=2|2+
 * rowspan=2|
 * β+α ($19.014$)
 * 16Oxygen
 * 21Sodium
 * style="text-align:right" | 11
 * style="text-align:right" | 10
 * β+
 * 21Neon
 * 3/2+
 * rowspan=2|[[Sodium|22Sodium]]
 * rowspan=2 style="text-align:right" | 11
 * rowspan=2 style="text-align:right" | 11
 * rowspan=2|$1 as$
 * rowspan=2|$20.007$
 * β+ ($447.9 ms$)
 * 22Neon
 * rowspan=2|3+
 * rowspan=2|Trace
 * ε ($75 %$)
 * 22Neon
 * style="text-indent:1em" | 22m1Sodium
 * colspan="3" style="text-indent:2em" | $25 %$
 * IT
 * 22Sodium
 * 1+
 * style="text-indent:1em" | 22m2Sodium
 * colspan="3" style="text-indent:2em" | $20.998$
 * IT
 * 22Sodium
 * 0+
 * 23Sodium
 * style="text-align:right" | 11
 * style="text-align:right" | 12
 * colspan=3 align=center|Stable
 * 3/2+
 * style="text-align:center"|$22.455 s$
 * [[Sodium|24Sodium]]
 * style="text-align:right" | 11
 * style="text-align:right" | 13
 * β−
 * 24Magnesium
 * 4+
 * Trace
 * rowspan=2 style="text-indent:1em" | 24mSodium
 * rowspan=2 colspan="3" style="text-indent:2em" | $21.994$
 * rowspan=2|$2.602 y$
 * IT ($90.57 %$)
 * 24Sodium
 * rowspan=2|1+
 * rowspan=2|
 * β− ($9.43 %$)
 * 24Magnesium
 * 25Sodium
 * style="text-align:right" | 11
 * style="text-align:right" | 14
 * β−
 * 25Magnesium
 * 5/2+
 * 26Sodium
 * style="text-align:right" | 11
 * style="text-align:right" | 15
 * β−
 * 26Magnesium
 * 3+
 * style="text-indent:1em" | 26mSodium
 * colspan="3" style="text-indent:2em" | $583.05 keV$
 * IT
 * 26Sodium
 * 1+
 * rowspan=2|27Sodium
 * rowspan=2 style="text-align:right" | 11
 * rowspan=2 style="text-align:right" | 16
 * rowspan=2| $243 ns$
 * rowspan=2| $657 keV$
 * β− ($19.6 ps$)
 * 27Magnesium
 * rowspan=2|5/2+
 * rowspan=2|
 * β−n ($22.99$)
 * 26Magnesium
 * rowspan=2|28Sodium
 * rowspan=2 style="text-align:right" | 11
 * rowspan=2 style="text-align:right" | 17
 * rowspan=2|$1$
 * rowspan=2|$23.991$
 * β− ($14.956 h$)
 * 28Magnesium
 * rowspan=2|1+
 * rowspan=2|
 * β−n ($472.207 keV$)
 * 27Magnesium
 * rowspan=3|29Sodium
 * rowspan=3 style="text-align:right" | 11
 * rowspan=3 style="text-align:right" | 18
 * rowspan=3|$20.18 ms$
 * rowspan=3|$99.95 %$
 * β− ($0.05 %$)
 * 29Magnesium
 * rowspan=3|3/2+
 * rowspan=3|
 * β−n ($24.99$)
 * 28Magnesium
 * β−2n ?
 * 27Magnesium ?
 * rowspan=4|30Sodium
 * rowspan=4 style="text-align:right" | 11
 * rowspan=4 style="text-align:right" | 19
 * rowspan=4|$59.1 s$
 * rowspan=4|$25.993$
 * β− ($1.071 s$)
 * 30Magnesium
 * rowspan=4|2+
 * rowspan=4|
 * β−n ($82.4 keV$)
 * 29Magnesium
 * β−2n ($4.35 μs$)
 * 28Magnesium
 * β−α ($26.994$)
 * 26Neon
 * rowspan=4|31Sodium
 * rowspan=4 style="text-align:right" | 11
 * rowspan=4 style="text-align:right" | 20
 * rowspan=4|$301 ms$
 * rowspan=4|$99.902 %$
 * β− (> $0.098 %$)
 * 31Magnesium
 * rowspan=4|3/2+
 * rowspan=4|
 * β−n ($27.999$)
 * 30Magnesium
 * β−2n ($33.1 ms$)
 * 29Magnesium
 * β−3n (< $99.42 %$)
 * 28Magnesium
 * rowspan=3|32Sodium
 * rowspan=3 style="text-align:right" | 11
 * rowspan=3 style="text-align:right" | 21
 * rowspan=3|$0.58 %$
 * rowspan=3|$29.003$
 * β− ($43.2 ms$)
 * 32Magnesium
 * rowspan=3|(3−)
 * rowspan=3|
 * β−n ($78 %$)
 * 31Magnesium
 * β−2n ($22 %$)
 * 30Magnesium
 * rowspan=3|33Sodium
 * rowspan=3 style="text-align:right" | 11
 * rowspan=3 style="text-align:right" | 22
 * rowspan=3|$30.009$
 * rowspan=3|$45.9 ms$
 * β−n ($70.2 %$)
 * 32Magnesium
 * rowspan=3|(3/2+)
 * rowspan=3|
 * β− ($28.6 %$)
 * 33Magnesium
 * β−2n ($1.24 %$)
 * 31Magnesium
 * rowspan=3|34Sodium
 * rowspan=3 style="text-align:right" | 11
 * rowspan=3 style="text-align:right" | 23
 * rowspan=3|$0 %$
 * rowspan=3|$31.013$
 * β−2n (~$16.8 ms$)
 * 32Magnesium
 * rowspan=3|1+
 * rowspan=3|
 * β− (~$63.2 %$)
 * 34Magnesium
 * β−n (~$36 %$)
 * 33Magnesium
 * rowspan=3|35Sodium
 * rowspan=3 style="text-align:right" | 11
 * rowspan=3 style="text-align:right" | 24
 * rowspan=3|$0.73 %$#
 * rowspan=3|$0.05 %$
 * β−
 * 35Magnesium
 * rowspan=3|3/2+#
 * rowspan=3|
 * β−n ?
 * 34Magnesium ?
 * β−2n ?
 * 33Magnesium ?
 * rowspan=3|37Sodium
 * rowspan=3 style="text-align:right" | 11
 * rowspan=3 style="text-align:right" | 26
 * rowspan=3|$32.02$#
 * rowspan=3|1# ms [> $12.9 ms$]
 * β− ?
 * 37Magnesium ?
 * rowspan=3|3/2+#
 * rowspan=3|
 * β−n ?
 * 36Magnesium ?
 * β−2n ?
 * 35Magnesium ?
 * rowspan=3|39Sodium
 * rowspan=3 style="text-align:right" | 11
 * rowspan=3 style="text-align:right" | 28
 * rowspan=3|$66.4 %$#
 * rowspan=3|1# ms [> $26 %$]
 * β− ?
 * 39Magnesium ?
 * rowspan=3|3/2+#
 * rowspan=3|
 * β−n ?
 * 38Magnesium ?
 * β−2n ?
 * 37Magnesium ?
 * rowspan=3 style="text-align:right" | 22
 * rowspan=3|$7.6 %$
 * rowspan=3|$33.026$
 * β−n ($8.2 ms$)
 * 32Magnesium
 * rowspan=3|(3/2+)
 * rowspan=3|
 * β− ($47 %$)
 * 33Magnesium
 * β−2n ($40 %$)
 * 31Magnesium
 * rowspan=3|34Sodium
 * rowspan=3 style="text-align:right" | 11
 * rowspan=3 style="text-align:right" | 23
 * rowspan=3|$13 %$
 * rowspan=3|$34.034$
 * β−2n (~$5.5 ms$)
 * 32Magnesium
 * rowspan=3|1+
 * rowspan=3|
 * β− (~$50 %$)
 * 34Magnesium
 * β−n (~$35 %$)
 * 33Magnesium
 * rowspan=3|35Sodium
 * rowspan=3 style="text-align:right" | 11
 * rowspan=3 style="text-align:right" | 24
 * rowspan=3|$15 %$#
 * rowspan=3|$35.041$
 * β−
 * 35Magnesium
 * rowspan=3|3/2+#
 * rowspan=3|
 * β−n ?
 * 34Magnesium ?
 * β−2n ?
 * 33Magnesium ?
 * rowspan=3|37Sodium
 * rowspan=3 style="text-align:right" | 11
 * rowspan=3 style="text-align:right" | 26
 * rowspan=3|$1.5 ms$#
 * rowspan=3|1# ms [> $37.057$]
 * β− ?
 * 37Magnesium ?
 * rowspan=3|3/2+#
 * rowspan=3|
 * β−n ?
 * 36Magnesium ?
 * β−2n ?
 * 35Magnesium ?
 * rowspan=3|39Sodium
 * rowspan=3 style="text-align:right" | 11
 * rowspan=3 style="text-align:right" | 28
 * rowspan=3|$1.5 μs$#
 * rowspan=3|1# ms [> $39.075$]
 * β− ?
 * 39Magnesium ?
 * rowspan=3|3/2+#
 * rowspan=3|
 * β−n ?
 * 38Magnesium ?
 * β−2n ?
 * 37Magnesium ?
 * rowspan=3 style="text-align:right" | 11
 * rowspan=3 style="text-align:right" | 28
 * rowspan=3|$400 ns$#
 * rowspan=3|1# ms [> $2.602 years$]
 * β− ?
 * 39Magnesium ?
 * rowspan=3|3/2+#
 * rowspan=3|
 * β−n ?
 * 38Magnesium ?
 * β−2n ?
 * 37Magnesium ?
 * β−2n ?
 * 37Magnesium ?

Sodium-22
Sodium-22 is a radioactive isotope of sodium, undergoing positron emission to with a half-life of $14.956 hours$. 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.

Sodium-23
Sodium-23 is an isotope of sodium with an atomic mass of 22.98976928. It is the only stable isotope of sodium and also the only primordial isotope. Because of its abundance, sodium-23 is used in nuclear magnetic resonance in various research fields, including materials science and battery research. Sodium-23 relaxation has applications in studying cation-biomolecule interactions, intracellular and extracellular sodium, ion transport in batteries, and quantum information processing.

Sodium-24
Sodium-24 is radioactive and can be created from common sodium-23 by neutron activation. With a half-life of ⇭⇭⇭, decays to  by emission of an electron and two gamma rays.

Exposure of the human body to intense neutron radiation creates in the blood plasma. Measurements of its quantity can be done to determine the absorbed radiation dose of a patient. This can be used to determine the type of medical treatment required.

When sodium is used as coolant in fast breeder reactors, is created, which makes the coolant radioactive. When the decays, it causes a buildup of magnesium in the coolant. Since the half-life is short, the 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, 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 and produce intense gamma-ray emissions for a few days.