Isotopes of cobalt

Naturally occurring cobalt (27Co) is composed of 1 stable isotope, 59Co. 28 radioisotopes have been characterized with the most stable being 60Co with a half-life of 5.2714 years, 57Co with a half-life of 271.8 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 11 meta states, all of which have half-lives less than 15 minutes.

The isotopes of cobalt range in atomic weight from 47Co to 75Co. 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 iron isotopes and the primary products after are nickel isotopes.

Radioactive isotopes can be produced by various nuclear reactions. For example, the isotope 57Co is produced by cyclotron irradiation of iron. The principal reaction involved is the (d,n) reaction 56Fe + 2H → n + 57Co.[2]

Main isotopes of cobalt (27Co)
Iso­tope Decay
abun­dance half-life (t1/2) mode pro­duct
56Co syn 77.27 d ε 56Fe
57Co syn 271.79 d ε 57Fe
58Co syn 70.86 d ε 58Fe
59Co 100% stable
60Co syn 5.2714 y β, γ 60Ni
Standard atomic weight Ar, standard(Co)
  • 58.933194(4)[1]

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 B12 uptake. It is useful for the Schilling test.[3]

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 quantities, and for its high radioactive activity simply by exposing natural cobalt to neutrons in a reactor for a given time. The uses for industrial cobalt include:

Cobalt-57 is used as a source in Mössbauer spectroscopy of iron-containing samples. The electron capture decay of the 57Co forms an excited state of the 57Fe nucleus, which in turn decays to the ground state with emission of a gamma ray. Measurement of the gamma ray spectrum provides information about the chemical state of the iron atom in the sample.

List of isotopes

nuclide
symbol
Z(p) N(n)  
isotopic mass (u)
 
half-life decay
mode(s)[4][n 1]
daughter
isotope(s)[n 2]
nuclear
spin and
parity
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)# p 47Fe 6+#
49Co 27 22 48.98972(28)# <35 ns p (>99.9%) 48Fe 7/2−#
β+ (<.1%) 49Fe
50Co 27 23 49.98154(18)# 44(4) ms β+, p (54%) 49Mn (6+)
β+ (46%) 50Fe
51Co 27 24 50.97072(16)# 60# ms [>200 ns] β+ 51Fe 7/2−#
52Co 27 25 51.96359(7)# 115(23) ms β+ 52Fe (6+)
52mCo 380(100)# keV 104(11)# ms β+ 52Fe 2+#
IT 52Co
53Co 27 26 52.954219(19) 242(8) ms β+ 53Fe 7/2−#
53mCo 3197(29) keV 247(12) ms β+ (98.5%) 53Fe (19/2−)
p (1.5%) 52Fe
54Co 27 27 53.9484596(8) 193.28(7) ms β+ 54Fe 0+
54mCo 197.4(5) keV 1.48(2) min β+ 54Fe (7)+
55Co 27 28 54.9419990(8) 17.53(3) h β+ 55Fe 7/2−
56Co 27 29 55.9398393(23) 77.233(27) d β+ 56Fe 4+
57Co 27 30 56.9362914(8) 271.74(6) d EC 57Fe 7/2−
58Co 27 31 57.9357528(13) 70.86(6) d β+ 58Fe 2+
58m1Co 24.95(6) keV 9.04(11) h IT 58Co 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) y β, γ 60Ni 5+
60mCo 58.59(1) keV 10.467(6) min IT (99.76%) 60Co 2+
β (.24%) 60Ni
61Co 27 34 60.9324758(10) 1.650(5) h β 61Ni 7/2−
62Co 27 35 61.934051(21) 1.50(4) min β 62Ni 2+
62mCo 22(5) keV 13.91(5) min β (99%) 62Ni 5+
IT (1%) 62Co
63Co 27 36 62.933612(21) 26.9(4) s β 63Ni 7/2−
64Co 27 37 63.935810(21) 0.30(3) s β 64Ni 1+
65Co 27 38 64.936478(14) 1.20(6) s β 65Ni (7/2)−
66Co 27 39 65.93976(27) 0.18(1) s β 66Ni (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 β 67Ni (7/2−)#
68Co 27 41 67.94487(34) 0.199(21) s β 68Ni (7-)
68mCo 150(150)# keV 1.6(3) s (3+)
69Co 27 42 68.94632(36) 227(13) ms β (>99.9%) 69Ni 7/2−#
β, n (<.1%) 68Ni
70Co 27 43 69.9510(9) 119(6) ms β (>99.9%) 70Ni (6-)
β, n (<.1%) 69Ni
70mCo 200(200)# keV 500(180) ms (3+)
71Co 27 44 70.9529(9) 97(2) ms β (>99.9%) 71Ni 7/2−#
β, n (<.1%) 70Ni
72Co 27 45 71.95781(64)# 62(3) ms β (>99.9%) 72Ni (6-,7-)
β, n (<.1%) 71Ni
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−#
  1. ^ Abbreviations:
    EC: Electron capture
    IT: Isomeric transition
  2. ^ Bold for stable isotopes

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.
  • Nuclide masses are given by IUPAP Commission on Symbols, Units, Nomenclature, Atomic Masses and Fundamental Constants (SUNAMCO)
  • Isotope abundances are given by IUPAC Commission on Isotopic Abundances and Atomic Weights (CIAAW)

References

  1. ^ Meija, J.; 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.
  2. ^ L. E. Diaz. "Cobalt-57: Production". JPNM Physics Isotopes. University of Harvard. Retrieved 2013-11-15.
  3. ^ L. E. Diaz. "Cobalt-57: Uses". JPNM Physics Isotopes. University of Harvard. Retrieved 2010-09-13.
  4. ^ "Universal Nuclide Chart". nucleonica. (Registration required (help)).
2002 Vitim event

The 2002 Vitim event or Bodaybo event is believed to be an impact by a bolide (fireball) in the Vitim River basin. It occurred near the town of Bodaybo in the Mamsko-Chuisky district of Irkutsk Oblast, Siberia, Russia on September 25, 2002 at approximately 22:00 (local time, UTC/GMT +9 hours: ISO 8601 format 2002-09-25T13:00Z). The event was detected by a US military missile-defense satellite.

Cobalt

Cobalt is a chemical element with symbol Co and atomic number 27. Like nickel, cobalt is found in the Earth's crust only in chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal.

Cobalt-based blue pigments (cobalt blue) have been used since ancient times for jewelry and paints, and to impart a distinctive blue tint to glass, but the color was later thought by alchemists to be due to the known metal bismuth. Miners had long used the name kobold ore (German for goblin ore) for some of the blue-pigment producing minerals; they were so named because they were poor in known metals, and gave poisonous arsenic-containing fumes when smelted. In 1735, such ores were found to be reducible to a new metal (the first discovered since ancient times), and this was ultimately named for the kobold.

Today, some cobalt is produced specifically from one of a number of metallic-lustered ores, such as for example cobaltite (CoAsS). The element is however more usually produced as a by-product of copper and nickel mining. The copper belt in the Democratic Republic of the Congo (DRC) and Zambia yields most of the global cobalt production. The DRC alone accounted for more than 50% of world production in 2016 (123,000 tonnes), according to Natural Resources Canada.Cobalt is primarily used in the manufacture of magnetic, wear-resistant and high-strength alloys. The compounds cobalt silicate and cobalt(II) aluminate (CoAl2O4, cobalt blue) give a distinctive deep blue color to glass, ceramics, inks, paints and varnishes. Cobalt occurs naturally as only one stable isotope, cobalt-59. Cobalt-60 is a commercially important radioisotope, used as a radioactive tracer and for the production of high energy gamma rays.

Cobalt is the active center of a group of coenzymes called cobalamins. vitamin B12, the best-known example of the type, is an essential vitamin for all animals. Cobalt in inorganic form is also a micronutrient for bacteria, algae, and fungi.

Cobalt-60

Cobalt-60 (60Co), is a synthetic radioactive isotope of cobalt with a half-life of 5.2747 years. It is produced artificially in nuclear reactors. Deliberate industrial production depends on neutron activation of bulk samples of the monoisotopic and mononuclidic cobalt isotope 59Co. Measurable quantities are also produced as a by-product of typical nuclear power plant operation and may be detected externally when leaks occur. In the latter case (in the absence of added cobalt) the incidentally produced 60Co is largely the result of multiple stages of neutron activation of iron isotopes in the reactor's steel structures via the creation of 59Co precursor. The simplest case of the latter would result from the activation of 58Fe. 60Co decays by beta decay to the stable isotope nickel-60 (60Ni). The activated nickel nucleus emits two gamma rays with energies of 1.17 and 1.33 MeV, hence the overall nuclear equation of the reaction is 5927Co + n → 6027Co → 6028Ni + e− + νe + gamma rays.

Thomas J. Parmley

Thomas Jennison Parmley (November 2, 1897 – September 15, 1997) was a physics professor at the University of Utah. He served as chairman of the UofU's physics department from 1957 to 1963.Parmley was born in Scofield, Utah to William and Mary Veal Parmley. His father was killed in the Scofield Mine disaster in that town in 1900. In 1921, he received his bachelor's degree from the University of Utah where he was a founding member of the Sigma Pi fraternity chapter. While still being an undergraduate, he worked as a chemist for the U.S. Smeltering Company. In 1923 he married LaVern W. Parmley who served as general president of the Primary of The Church of Jesus Christ of Latter-day Saints (LDS Church). He then earned his Ph.D. from Cornell University in 1927. Prior to joining the faculty of the University of Utah, Parmley was involved in cyclotron research at the University of California, Berkeley. While there he was the lead author of the paper "The Radioactives of some high-mass isotopes of Cobalt"Parmley was a member of the LDS Church. He served for 13 years on the General Board of the Deseret Sunday School Union.Parmley was involved with the Atomic Energy Commission and the National Bureau of Standards. He was a member of the American Institute of Physics.Among Parmley's students at the University of Utah were Don Lind and prominent cardiac surgeon and LDS Apostle Russell M. Nelson.

One of the main physics lecture halls at the University of Utah is named after him as is a scholarship. Parmley's son William became a general authority in the LDS Church.

Although Parmley retired from formal teaching in 1980, his zeal for learning and expanding the minds of young people persisted though his whole life. He appreciated science, learning, and discovery, but his true passion was for teaching and helping young students experience the excitement of learning and discovery. If you asked him, assuredly he would list his greatest accomplishments as the lives of his children and accomplishments of his students. His influence continues today in those who knew his kindness, generosity, faith and his amazing enthusiasm for life and learning.

In 1996 he was name the university's Centennial Professor.

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