Isotopes of carbon

Source: Wikipedia, the free encyclopedia.
"Carbon-15" redirects here. For the firearm, see Carbon 15.
Isotopes of carbon (6C)
Main isotopes Decay
abun­dance half-life (t1/2) mode pro­duct
11C synth 20.34 min
β+
11B
12C 98.9%
stable
13C 1.06% stable
14C 1
ppt
(1⁄1012) 		5.70×103 y
β−
14N
talk
  • edit

    • Carbon (6C) has 14 known isotopes, from 8
    C
     to 20
    C
     as well as 22
    C
    , of which 12
    C
     and 13
    C
     are stable. The longest-lived radioisotope is 14
    C
    , with a half-life of 5.70(3)×103 years. This is also the only carbon radioisotope found in nature, as trace quantities are formed cosmogenically by the reaction 14
    N
     +
    n
     → 14
    C
     + 1
    H
    . The most stable artificial radioisotope is 11
    C
    , which has a half-life of 20.3402(53) min. All other radioisotopes have half-lives under 20 seconds, most less than 200 milliseconds. The least stable isotope is 8
    C
    , with a half-life of 3.5(1.4)×10−21 s. Light isotopes tend to decay into isotopes of boron and heavy ones tend to decay into isotopes of nitrogen.

    List of isotopes

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

    [resonance width]
    Decay
    mode[4]
    [n 2]
    		 Daughter
    isotope
    [n 3]
    Spin and
    parity[4]
    [n 4][n 5]
    		 Natural abundance (mole fraction)
    Normal proportion[4] Range of variation
    8
    C
         		6 2 8.037643(20) 3.5(1.4) zs
    [230(50) keV]     		2p 6
    Be
    [n 6]     		0+
    9
    C
         		6 3 9.0310372(23) 126.5(9) ms β+ (54.1(1.7)%) 9
    B
         		3/2−
    β+α (38.4(1.6)%) 5
    Li
    [n 7]
    β+p (7.5(6)%) 8
    Be
    [n 8]
    10
    C
         		6 4 10.01685322(8) 19.3011(15) s β+ 10
    B
         		0+
    11
    C
    [n 9]     		6 5 11.01143260(6) 20.3402(53) min β+ 11
    B
         		3/2−
    11m
    C
         		12160(40) keV p ?[n 10] 10
    B
     ?     		1/2+
    12
    C
         		6 6 12 exactly[n 11] Stable 0+ [0.9884, 0.9904][5]
    13
    C
    [n 12]     		6 7 13.003354835336(252) Stable 1/2− [0.0096, 0.0116][5]
    14
    C
    [n 13]     		6 8 14.003241989(4) 5.70(3)×103 y β− 14
    N
         		0+ Trace[n 14] < 10−12
    14m
    C
         		22100(100) keV
    IT
    		 14
    C
         		(2−)
    15
    C
         		6 9 15.0105993(9) 2.449(5) s β− 15
    N
         		1/2+
    16
    C
         		6 10 16.014701(4) 750(6) ms β−n (99.0(3)%) 15
    N
         		0+
    β− (1.0(3)%) 16
    N
    17
    C
         		6 11 17.022579(19) 193(6) ms β− (71.6(1.3)%) 17
    N
         		3/2+
    β−n (28.4(1.3)%) 16
    N
    β−2n ?[n 10] 15
    N
     ?
    18
    C
         		6 12 18.02675(3) 92(2) ms β− (68.5(1.5)%) 18
    N
         		0+
    β−n (31.5(1.5)%) 17
    N
    β−2n ?[n 10] 16
    N
     ?
    19
    C
    [n 15]     		6 13 19.03480(11) 46.2(2.3) ms β−n (47(3)%) 18
    N
         		1/2+
    β− (46.0(4.2)%) 19
    N
    β−2n (7(3)%) 17
    N
    20
    C
         		6 14 20.04026(25) 16(3) ms β−n (70(11)%) 19
    N
         		0+
    β−2n (< 18.6%) 18
    N
    β− (> 11.4%) 20
    N
    22
    C
    [n 16]     		6 16 22.05755(25) 6.2(1.3) ms β−n (61(14)%) 21
    N
         		0+
    β−2n (< 37%) 20
    N
    β− (> 2%) 22
    N
    This table header & footer:
    1. ^ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
    2. ^ Modes of decay:
      EC: Electron capture


      n: Neutron emission
      p: Proton emission
    3. ^ Bold symbol as daughter – Daughter product is stable.
    4. ^ ( ) spin value – Indicates spin with weak assignment arguments.
    5. ^ # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
    6. ^ Subsequently decays by double proton emission to 4
      He
       for a net reaction of 8
      C
       → 4
      He
       + 41
      H
    7. ^ Immediately decays by proton emission to 4
      He
       for a net reaction of 9
      C
       → 2 4
      He
       + 1
      H
       +
      e−
    8. ^ Immediately decays into two 4
      He
       atoms for a net reaction of 9
      C
       → 2 4
      He
       + 1
      H
       +
      e−
    9. ^ Used for labeling molecules in PET scans
    10. ^ a b c Decay mode shown is energetically allowed, but has not been experimentally observed to occur in this nuclide.
    11. unified atomic mass unit
      is defined as 1/12 of the mass of an unbound atom of carbon-12 in its ground state.
    12. ^ Ratio of 12C to 13C used to measure biological productivity in ancient times and differing types of photosynthesis
    13. carbon dating
      )
    14. 14
      N
       (14
      N
       +
      n
       → 14
      C
       + 1
      H
      )
    15. ^ Has 1 halo neutron
    16. ^ Has 2 halo neutrons

    Carbon-11

    Carbon-11 or 11
    C
     is a radioactive isotope of

    boron-11. This decay mainly occurs due to positron emission, with around 0.19–0.23% of decays instead occurring by electron capture.[6][7] It has a half-life
    of 20.3402(53) min.

    11
    C
     →
    11
    B
     +
    e+
     +
    ν
    e     + 0.96 MeV
    11
    C
     +
    e−
     → 11
    B
     +
    ν
    e     + 1.98 MeV

    It is produced from nitrogen in a cyclotron by the reaction

    14
    N
     +
    p
     → 11
    C
     + 4
    He

    Carbon-11 is commonly used as a

    radioisotope for the radioactive labeling of molecules in positron emission tomography. Among the many molecules used in this context are the radioligands [11
    C
    ]DASB     and [11
    C
    ]Cimbi-5
    .

    Natural isotopes

    Main articles: Carbon-12, Carbon-13, and Carbon-14

    There are three naturally occurring isotopes of carbon: 12, 13, and 14. 12
    C
     and 13
    C
     are stable, occurring in a natural proportion of approximately 93:1. 14
    C
     is produced by thermal neutrons from cosmic radiation in the upper atmosphere, and is transported down to earth to be absorbed by living biological material. Isotopically, 14
    C
     constitutes a negligible part; but, since it is radioactive with a half-life of 5.70(3)×103 years, it is radiometrically detectable. Since dead tissue does not absorb 14
    C
    , the amount of 14
    C
     is one of the methods used within the field of archeology for radiometric dating of biological material.

    Paleoclimate

    12
    C
     and 13
    C
     are measured as the

    North Atlantic), the water carries 12
    C
     back up with it; when the ocean was less stratified than today, there was much more 12
    C
     in the skeletons of surface-dwelling species. Other indicators of past climate include the presence of tropical species and coral growth rings.[9]

    Tracing food sources and diets

    The quantities of the different isotopes can be measured by

    standard; the result (e.g., the delta of the 13
    C
     = δ13
    C
    ) is expressed as parts per thousand (‰):[10]

    ‰

    Stable carbon isotopes in

    crabgrass) follow a C4 photosynthetic pathway that produces δ13C values averaging about −12.5‰.[11]

    It follows that eating these different plants will affect the δ13C values in the consumer's body tissues. If an animal (or human) eats only C3 plants, their δ13C values will be from −18.5 to −22.0‰ in their bone

    hydroxylapatite of their teeth and bones.[12]

    In contrast, C4 feeders will have bone collagen with a value of −7.5‰ and hydroxylapatite value of −0.5‰.

    In actual case studies, millet and maize eaters can easily be distinguished from rice and wheat eaters. Studying how these dietary preferences are distributed geographically through time can illuminate migration paths of people and dispersal paths of different agricultural crops. However, human groups have often mixed C3 and C4 plants (northern Chinese historically subsisted on wheat and millet), or mixed plant and animal groups together (for example, southeastern Chinese subsisting on rice and fish).[13]

    See also

    References

    1. ^ "Standard Atomic Weights: Carbon". CIAAW. 2009.
    2. ISSN 1365-3075
      .
    3. doi:10.1088/1674-1137/abddaf
      .
    4. ^
      doi:10.1088/1674-1137/abddae
      .
    5. ^ a b "Atomic Weight of Carbon". CIAAW.
    6. doi:10.1080/14786435708242737
      .
    7. doi:10.1016/0375-9474(67)90712-9
      .
    8. S2CID 129194624
      .
    9. ISBN 1-920885-84-6
    10. OCLC 794619582
      .
    11. S2CID 29110460
      . Retrieved 17 November 2022.
    12. ^ Tycot, R. H. (2004). M. Martini; M. Milazzo; M. Piacentini (eds.). "Stable isotopes and diet: you are what you eat" (PDF). Proceedings of the International School of Physics "Enrico Fermi" Course CLIV.
    13. PMID 16768822
      .
    Retrieved from "https://en.wikipedia.org/w/index.php?title=Isotopes_of_carbon&oldid=1215595768"