Isotopes of sodium

From Wikipedia, the free encyclopedia
  (Redirected from Sodium-22)
Jump to: navigation, search

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 standard atomic mass: 22.98976928(2) u. 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 least stable 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.

Sodium-22 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[edit]

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) yr 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. ^ a b Cosmogenic nuclide

Notes[edit]

  • 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[edit]

Sodium-24 is one of the more important isotopes of sodium. 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

References[edit]

External links[edit]

  1. ^ http://www.nucleonica.net/unc.aspx


Isotopes of neon Isotopes of sodium Isotopes of magnesium
Table of nuclides