Isotopes of fluorine

Summary

Fluorine (9F) has 18 known isotopes ranging from 13
F
to 31
F
(with the exception of 30
F
) and two isomers (18m
F
and 26m
F
). Only fluorine-19 is stable and naturally occurring in more than trace quantities; therefore, fluorine is a monoisotopic and mononuclidic element.

Main isotopes of fluorine (9F)
Iso­tope Decay
abun­dance half-life (t1/2) mode pro­duct
18F trace 109.734(8) min β+ 18O
19F 100% stable
Standard atomic weight Ar°(F)
  • 18.998403162±0.000000005
  • 18.998±0.001 (abridged)[1][2]

The longest-lived radioisotope is 18
F
; it has a half-life of 109.734(8) min. All other fluorine isotopes have half-lives of less than a minute, and most of those less than a second. The least stable known isotope is 14
F
, whose half-life is 500(60) yoctoseconds,[3] corresponding to a resonance width of 910(100) keV.

List of isotopesEdit

Nuclide[4]
[n 1]
Z N Isotopic mass (Da)[5]
[n 2][n 3]
Half-life
[n 4]
Decay
mode

[n 5]
Daughter
isotope

[n 6]
Spin and
parity
[n 7][n 4]
Natural abundance (mole fraction)
Excitation energy Normal proportion Range of variation
13
F
[6]
9 4 13045120(540)# p ?[n 8] 12
O
 ?
[n 9]
14
F
9 5 14.034320(40) 500(60) ys
[910(100) keV]
p ?[n 8] 13
O
 ?
2−
15
F
9 6 15.017785(15) 1.1(3) zs
[376 keV]
p 14
O
1/2+
16
F
9 7 16.011460(6) 21(5) zs
[21.3(5.1) keV]
p 15
O
0−
17
F
9 8 17.00209524(27) 64.370(27) s β+ 17
O
5/2+
18
F
[n 10]
9 9 18.0009373(5) 109.734(8) min β+ 18
O
1+ Trace
18m
F
1121.36(15) keV 162(7) ns IT 18
F
5+
19
F
9 10 18.998403162067(883) Stable 1/2+ 1
20
F
9 11 19.99998125(3) 11.0062(80) s β 20
Ne
2+
21
F
9 12 20.9999489(19) 4.158(20) s β 21
Ne
5/2+
22
F
9 13 22.002999(13) 4.23(4) s β (> 89%) 22
Ne
(4+)
βn (< 11%) 21
Ne
23
F
9 14 23.003530(40) 2.23(14) s β (> 86%) 23
Ne
5/2+
βn (< 14%) 22
Ne
24
F
9 15 24.008100(100) 384(16) ms β (> 94.1%) 24
Ne
3+
βn (< 5.9%) 23
Ne
25
F
9 16 25.012170(100) 80(9) ms β (76.9(4.5)%) 25
Ne
(5/2+)
βn (23.1(4.5)%) 24
Ne
β2n ?[n 8] 23
Ne
 ?
26
F
9 17 26.020050(110) 8.2(9) ms β (86.5(4.0)%) 26
Ne
1+
βn (13.5(4.0)%) 25
Ne
β2n ?[n 8] 24
Ne
 ?
26m
F
643.4(1) keV 2.2(1) ms IT (82(11)%) 26
F
(4+)
βn (12(8)%) 25
Ne
β ?[n 8] 26
Ne
 ?
27
F
9 18 27.026980(130) 5.0(2) ms βn (77(21)%) 26
Ne
5/2+#
β (23(21)%) 27
Ne
β2n ?[n 8] 25
Ne
 ?
28
F
9 19 28.035860(130) 46 zs n 27
F
(4−)
29
F
9 20 29.043100(560) 2.5(3) ms βn (60(40)%) 28
Ne
(5/2+)
β (40(40)%) 29
Ne
β2n ?[n 8] 27
Ne
 ?
30
F
9 21 30.052560(540)# < 260 ns n ?[n 8] 29
F
 ?
31
F
9 22 31.06020(570)# 2 ms# [> 260 ns] β ?[n 8] 31
Ne
 ?
5/2+#
βn ?[n 8] 30
Ne
 ?
β2n ?[n 8] 29
Ne
 ?
This table header & footer:
  1. ^ mF – 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. ^ a b # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  5. ^ Modes of decay:
    EC: Electron capture
    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. ^ a b c d e f g h i j k Decay mode shown is energetically allowed, but has not been experimentally observed to occur in this nuclide.
  9. ^ The 5/2+ excited state was likely observed, but observation of the ground state is uncertain.[6]
  10. ^ Has medicinal uses

Fluorine-18Edit

Of the unstable nuclides of fluorine, 18
F
has the longest half-life, 109.734(8) min. It decays to 18
O
via β+ decay. For this reason 18
F
is a commercially important source of positrons. Its major value is in the production of the radiopharmaceutical fludeoxyglucose, used in positron emission tomography in medicine.

Fluorine-18 is the lightest unstable nuclide with equal odd numbers of protons and neutrons, having 9 of each. (See also the "magic numbers" discussion of nuclide stability.)[7]

Fluorine-19Edit

Fluorine-19 is the only stable isotope of fluorine. Its abundance is 100%; no other isotopes of fluorine exist in significant quantities. Its binding energy is 147801.3648(38) keV. Fluorine-19 is NMR-active with a spin of 1/2+, so it is used in fluorine-19 NMR spectroscopy.

Fluorine-20Edit

Fluorine-20 is one of the more unstable isotopes of fluorine. It has a half-life of 11.0062(80) s and decays via beta decay to the stable nuclide 20
Ne
. Its specific radioactivity is 1.8693(14)×10+21 Bq/g and has a mean lifetime of 15.879(12) s.

Fluorine-21Edit

Fluorine-21, as with fluorine-20, is also an unstable isotope of fluorine. It has a half-life of 4.158(20) s. It undergoes beta decay as well, decaying to 21
Ne
, which is a stable nuclide. Its specific activity is 4.781(23)×10+21 Bq/g.

IsomersEdit

Only two nuclear isomers (long-lived excited nuclear states), fluorine-18m and fluorine-26m, have been characterized.[3] The half-life of 18m
F
before it undergoes isomeric transition is 162(7) nanoseconds.[3] This is less than the decay half-life of any of the fluorine radioisotope nuclear ground states except for mass numbers 14–16, 28, and 31. [8] The half-life of 26m
F
is 2.2(1) milliseconds; it decays mainly to its ground state of 26
F
or (rarely, via beta-minus decay) to one of high excited states of 26
Ne
with delayed neutron emission.[3]

External linksEdit

  • Information on Fluorine-21 from Wolframalpha.com
  • Information on Fluorine-20 from Wolframalpha.com

ReferencesEdit

  1. ^ "Standard Atomic Weights: Fluorine". CIAAW. 2021.
  2. ^ Meija, Juris; 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.
  3. ^ a b c d Kondev, F.G.; Wang, M.; Huang, W.J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
  4. ^ Half-life, decay mode, nuclear spin, and isotopic composition is sourced in:
    Kondev, F.G.; Wang, M.; Huang, W.J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
  5. ^ Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3): 030003. doi:10.1088/1674-1137/abddaf.
  6. ^ a b Charity, R. J. (2 April 2021). "Observation of the Exotic Isotope 13 F Located Four Neutrons beyond the Proton Drip Line". Physical Review Letters. 126 (13): 2501. doi:10.1103/PhysRevLett.126.132501. Retrieved 5 April 2021.
  7. ^ National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory.
  8. ^ Audi, G.; Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S. (2017). "The NUBASE2016 evaluation of nuclear properties" (PDF). Chinese Physics C. 41 (3): 030001. Bibcode:2017ChPhC..41c0001A. doi:10.1088/1674-1137/41/3/030001.