Isotopes of cobalt
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Naturally occurring cobalt (Co) is composed of 1 stable isotope, 59Co. 22 radioisotopes have been characterized with the most stable being 60Co with a half-life of 5.2714 years, 57Co with a half-life of 271.79 days, 56Co with a half-life of 77.27 days, and 58Co with a half-life of 70.86 days. All of the remaining radioactive isotopes have half-lives that are less than 18 hours and the majority of these have half-lives that are less than 1 second. This element also has 4 meta states, all of which have half-lives less than 15 minutes.
The isotopes of cobalt range in atomic weight from 50 u (50Co) to 73 u (73Co). The primary decay mode for isotopes with atomic mass unit values less than that of the most abundant stable isotope, 59Co, is electron capture and the primary mode of decay for those of greater than 59 atomic mass units is beta decay. The primary decay products before 59Co are element 26 (iron) isotopes and the primary products after are element 28 (nickel) isotopes.
Standard atomic mass: 58.933195(5) u
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[edit] Use of cobalt radioisotopes in medicine
Cobalt-60 (Co-60 or 60Co) is a radioactive metal that is used in radiotherapy. It produces two gamma rays with energies of 1.17 MeV and 1.33 MeV. The 60Co source is about 2 cm in diameter and as a result produces a geometric penumbra, making the edge of the radiation field fuzzy. The metal has the unfortunate habit of producing a fine dust, causing problems with radiation protection. The 60Co source is useful for about 5 years but even after this point is still very radioactive, and so cobalt machines have fallen from favor in the Western world where linacs are common.
Cobalt-57 (Co-57 or 57Co) is a radioactive metal that is used in medical tests; it is used as a radiolabel for vitamin B-12 uptake. It is useful for the Schilling test.[1]
[edit] Industrial uses for radioactive isotopes
Cobalt-60 (Co-60 or 60Co) is useful as a gamma ray source because it can be produced—in predictable quantity, and high activity—by simply exposing natural cobalt to neutrons in a reactor for a given time. It is used for
- sterilization of medical supplies, and medical waste;
- radiation treatment of foods for sterilization (cold pasteurization);
- industrial radiography (e.g., weld integrity radiographs);
- density measurements (e.g., concrete density measurements); and
- tank fill height switches.
[edit] Table
| nuclide symbol |
Z(p) | N(n) | isotopic mass (u) |
half-life | nuclear spin |
representative isotopic composition (mole fraction) |
range of natural variation (mole fraction) |
|---|---|---|---|---|---|---|---|
| excitation energy | |||||||
| 47Co | 27 | 20 | 47.01149(54)# | 7/2-# | |||
| 48Co | 27 | 21 | 48.00176(43)# | 6+# | |||
| 49Co | 27 | 22 | 48.98972(28)# | <35 ns | 7/2-# | ||
| 50Co | 27 | 23 | 49.98154(18)# | 44(4) ms | (6+) | ||
| 51Co | 27 | 24 | 50.97072(16)# | 60# ms [>200 ns] | 7/2-# | ||
| 52Co | 27 | 25 | 51.96359(7)# | 115(23) ms | (6+) | ||
| 52mCo | 380(100)# keV | 104(11)# ms | 2+# | ||||
| 53Co | 27 | 26 | 52.954219(19) | 242(8) ms | 7/2-# | ||
| 53mCo | 3197(29) keV | 247(12) ms | (19/2-) | ||||
| 54Co | 27 | 27 | 53.9484596(8) | 193.28(7) ms | 0+ | ||
| 54mCo | 197.4(5) keV | 1.48(2) min | (7)+ | ||||
| 55Co | 27 | 28 | 54.9419990(8) | 17.53(3) h | 7/2- | ||
| 56Co | 27 | 29 | 55.9398393(23) | 77.233(27) d | 4+ | ||
| 57Co | 27 | 30 | 56.9362914(8) | 271.74(6) d | 7/2- | ||
| 58Co | 27 | 31 | 57.9357528(13) | 70.86(6) d | 2+ | ||
| 58m1Co | 24.95(6) keV | 9.04(11) h | 5+ | ||||
| 58m2Co | 53.15(7) keV | 10.4(3) µs | 4+ | ||||
| 59Co | 27 | 32 | 58.9331950(7) | STABLE | 7/2- | 1.0000 | |
| 60Co | 27 | 33 | 59.9338171(7) | 5.2713(8) a | 5+ | ||
| 60mCo | 58.59(1) keV | 10.467(6) min | 2+ | ||||
| 61Co | 27 | 34 | 60.9324758(10) | 1.650(5) h | 7/2- | ||
| 62Co | 27 | 35 | 61.934051(21) | 1.50(4) min | 2+ | ||
| 62mCo | 22(5) keV | 13.91(5) min | 5+ | ||||
| 63Co | 27 | 36 | 62.933612(21) | 26.9(4) s | 7/2- | ||
| 64Co | 27 | 37 | 63.935810(21) | 0.30(3) s | 1+ | ||
| 65Co | 27 | 38 | 64.936478(14) | 1.20(6) s | (7/2)- | ||
| 66Co | 27 | 39 | 65.93976(27) | 0.18(1) s | (3+) | ||
| 66m1Co | 175(3) keV | 1.21(1) µs | (5+) | ||||
| 66m2Co | 642(5) keV | >100 µs | (8-) | ||||
| 67Co | 27 | 40 | 66.94089(34) | 0.425(20) s | (7/2-)# | ||
| 68Co | 27 | 41 | 67.94487(34) | 0.199(21) s | (7-) | ||
| 68mCo | 150(150)# keV | 1.6(3) s | (3+) | ||||
| 69Co | 27 | 42 | 68.94632(36) | 227(13) ms | 7/2-# | ||
| 70Co | 27 | 43 | 69.9510(9) | 119(6) ms | (6-) | ||
| 70mCo | 200(200)# keV | 500(180) ms | (3+) | ||||
| 71Co | 27 | 44 | 70.9529(9) | 97(2) ms | 7/2-# | ||
| 72Co | 27 | 45 | 71.95781(64)# | 62(3) ms | (6-,7-) | ||
| 73Co | 27 | 46 | 72.96024(75)# | 41(4) ms | 7/2-# | ||
| 74Co | 27 | 47 | 73.96538(86)# | 50# ms [>300 ns] | 0+ | ||
| 75Co | 27 | 48 | 74.96833(86)# | 40# ms [>300 ns] | 7/2-# | ||
[edit] Notes
- 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.
[edit] Table 2
| Isotope | Decay mechanism | Half life |
|---|---|---|
| Co-50 | positron emission | 44 millisecond |
| Co-51 | positron emission | unmeasured |
| Co-52 | positron emission | 0.12 second |
| Co-53 | positron emission | 0.24 second |
| Co-54 | positron emission | 193.2 millisecond |
| Co-55 | positron emission | 17.53 h |
| Co-56 | electron capture, positron emission | 77.3 d |
| Co-57 | positron emission | 271.8 d |
| Co-58 | electron capture | 70.88 d |
| Co-59 | stable | ∞ |
| Co-60 | beta decay | 5.271 yr |
| Co-61 | beta decay | 1.65 hr |
| Co-62 | beta decay | 1.5 min |
| Co-63 | beta decay | 27.5 second |
| Co-64 | beta decay | 0.30 second |
| Co-65 | beta decay | 1.17 second |
| Co-66 | beta decay | 0.190 second |
| Co-67 | beta decay | 0.43 second |
| Co-68 | beta decay | 0.20 second |
| Co-69 | beta decay | 0.22 second |
| Co-70 | beta decay | 0.13 second |
| Co-71 | beta decay | 0.21 second |
| Co-72 | beta decay | 90 millisecond |
[edit] References
- ^ JPNM Physics Isotopes
- ^ Nuclides and Isotopes: Chart of the Nuclides, 16th Edition, by Edward Baum, Harold Knox, and Thomas Miller; Knolls Atomic Power Laboratory; 2002
- Isotope masses from Ame2003 Atomic Mass Evaluation by G. Audi, A.H. Wapstra, C. Thibault, J. Blachot and O. Bersillon in Nuclear Physics A729 (2003).
- Isotopic compositions and standard atomic masses from Atomic weights of the elements. Review 2000 (IUPAC Technical Report). Pure Appl. Chem. Vol. 75, No. 6, pp. 683-800, (2003) and Atomic Weights Revised (2005).
- Half-life, spin, and isomer data selected from these sources. Editing notes on this article's talk page.
- Audi, Bersillon, Blachot, Wapstra. The Nubase2003 evaluation of nuclear and decay properties, Nuc. Phys. A 729, pp. 3-128 (2003).
- National Nuclear Data Center, Brookhaven National Laboratory. Information extracted from the NuDat 2.1 database (retrieved Sept. 2005).
- David R. Lide (ed.), Norman E. Holden in CRC Handbook of Chemistry and Physics, 85th Edition, online version. CRC Press. Boca Raton, Florida (2005). Section 11, Table of the Isotopes.
| Isotopes of iron | Isotopes of cobalt | Isotopes of nickel |
| Index to isotope pages · Table of nuclides | ||
