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.
|Main isotopes of cobalt (27Co)|
|Standard atomic weight Ar, standard(Co)|
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-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.
isotopic mass (u)
|range of natural|
|49Co||27||22||48.98972(28)#||<35 ns||p (>99.9%)||48Fe||7/2−#|
|50Co||27||23||49.98154(18)#||44(4) ms||β+, p (54%)||49Mn||(6+)|
|51Co||27||24||50.97072(16)#||60# ms [>200 ns]||β+||51Fe||7/2−#|
|52mCo||380(100)# keV||104(11)# ms||β+||52Fe||2+#|
|53mCo||3197(29) keV||247(12) ms||β+ (98.5%)||53Fe||(19/2−)|
|54mCo||197.4(5) keV||1.48(2) min||β+||54Fe||(7)+|
|58m1Co||24.95(6) keV||9.04(11) h||IT||58Co||5+|
|58m2Co||53.15(7) keV||10.4(3) µs||4+|
|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+|
|62mCo||22(5) keV||13.91(5) min||β− (99%)||62Ni||5+|
|66m1Co||175(3) keV||1.21(1) µs||(5+)|
|66m2Co||642(5) keV||>100 µs||(8-)|
|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|
|74Co||27||47||73.96538(86)#||50# ms [>300 ns]||0+|
|75Co||27||48||74.96833(86)#||40# ms [>300 ns]||7/2−#|
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.