Results for cobalt
On this page:
 
Dictionary:

cobalt

  ('bôlt') pronunciation
n. (Symbol Co)

A hard, brittle metallic element, found associated with nickel, silver, lead, copper, and iron ores and resembling nickel and iron in appearance. It is used chiefly for magnetic alloys, high-temperature alloys, and in the form of its salts for blue glass and ceramic pigments. Atomic number 27; atomic weight 58.9332; melting point 1,495°C; boiling point 2,900°C; specific gravity 8.9; valence 2, 3.

[German Kobalt, from Middle High German kobolt, variant of kobold, goblin (from silver miners' belief that cobalt had been placed by goblins who had stolen the silver).]


 
 

A lustrous, silvery-blue metallic chemical element, Co, with an atomic number of 27 and an atomic weight of 58.93. Metallic cobalt was isolated in 1735 by the Swedish scientist G. Brandt, who called the impure metal cobalt rex, after the ore from which it was extracted. The metal was shown to be a previously unknown element by T. O. Bergman in 1780.See also Periodic table.

Cobalt is a transition element in the same group as rhodium and iridium. In the periodic table it occupies a position between iron and nickel in the third period. Cobalt resembles iron and nickel in both its free and combined states, possessing similar tensile strength, machinability, thermal properties, and electrochemical behavior. Constituting 0.0029% of the Earth's crust, cobalt is widely distributed in nature, occurring in meteorites, stars, lunar rocks, seawater, fresh water, soils, plants, and animals. See also Periodic table; Transition elements.

Cobalt and its alloys resist wear and corrosion even at high temperatures. The most important commercial uses are in making alloys for heavy-wear, high-temperature, and magnetic applications. Small amounts of the element are required by plants and animals. The artificially produced radioactive isotope of cobalt, 60Co, has many medical and industrial applications.

Cobalt, with a melting point of 1495°C (2723°F) and a boiling point of 3100°C (5612°F), has a density (20°C; 68°F) of 8.90 g·cm−3, an electrical resistivity (20°C) of 6.24 microhm·cm, and a hardness (diamond pyramid, Vickers; 20°C) of 225. It is harder than iron and, although brittle, it can be machined. The latent heat of fusion is 259.4 joules/g, and the latent heat of vaporization is 6276 J/g; the specific heat (15–100°C; 59–212°F) is 0.442 J/g · °C. Cobalt is ferromagnetic, with the very high Curie temperature of 1121°C (2050°F). The electronic configuration is 1s22s22p63s23p63d74s2. At normal temperatures the stable crystal form of cobalt is hexagonal close-packed, but above 417°C (783°F) face-centered cubic is the stable structure. Although the finely divided metal is pyrophoric in air, cobalt is relatively unreactive and stable to oxygen in the air, unless heated. It is attacked by sulfuric, hydrochloric, and nitric acids, and more slowly by hydrofluoric and phosphoric acids, ammonium hydroxide, and sodium hydroxide. Cobalt reacts when heated with the halogens and other nonmetals such as boron, carbon, phosphorus, arsenic, antimony, and sulfur. Dinitrogen, superoxo, peroxo, and mixed hydride complexes also exist. In its compounds, cobalt exhibits all the oxidation states from −I to IV, the most common being II and III. The highest oxidation state is found in cesium hexafluorocobaltate(IV), Cs2CoF6, and a few other compounds.

There are over 200 ores known to contain cobalt; traces of the metal are found in many ores of iron, nickel, copper, silver, manganese, and zinc. However, the commercially important cobalt minerals are the arsenides, oxides, and sulfides. Zaire is the chief producer, followed by Zambia. Russia, Canada, Cuba, Australia, and New Caledonia produce most of the rest. Zaire and Zambia together account for just over 50% of the world's cobalt reserves. Nickel-containing laterites (hydrated iron oxides) found in the soils of the Celebes, Cuba, New Caledonia, and many other tropical areas are being developed as sources of cobalt. The manganese nodules found on the ocean floor are another large potential reserve of cobalt. They are estimated to contain at least 400 times as much cobalt as land-based deposits.

Since cobalt production is usually subsidiary to that of copper, nickel, or lead, extraction procedures vary according to which of these metals is associated with the cobalt. In general, the ore is roasted to remove stony gangue material as a slag, leaving a speiss of mixed metal and oxides, which is then reduced electrolytically, reduced thermally with aluminum, or leached with sulfuric acid to dissolve iron, cobalt, and nickel, leaving metallic copper behind. Lime is used to precipitate iron, and sodium hypochlorite is used to precipitate cobalt as the hydroxide. The cobalt hydroxide can be heated to give the oxide, which in turn is reduced to the metal by heating with charcoal.

Cobalt ores have long been used to produce a blue color in pottery, glass, enamels, and glazes. Cobalt is contained in Egyptian pottery dated as early as 2600 B.C. and in the blue and white porcelain ware of the Ming Dynasty in China (1368–1644).

An important modern industrial use involves the addition of small quantities of cobalt oxide during manufacture of ceramic materials to achieve a white color. The cobalt oxide counteracts yellow tints resulting from iron impurities. Cobalt oxide is also used in enamel coatings on steel to improve the adherence of the enamel to the metal. Cobalt arsenates, phosphates, and aluminates are used in artists' pigments, and various cobalt compounds are used in inks for full-color jet printing and in reactive dyes for cotton. Cobalt blue (Thenard's blue), one of the most durable of all blue pigments, is essentially cobalt aluminate. Cobalt linoleates, naphthenates, oleates, and ethylhexoates are used to speed up the drying of paints, lacquers, varnishes, and inks by promoting oxidation. In all, about a third of the world's cobalt production is used to make chemicals for the ceramic and paint industries.See also Dye.

Cobalt catalysts are used throughout the chemical industry for various processes. These include hydrogenations and dehydrogenations, halogenations, aminations, polymerizations (for example, butadiene), oxidation of xylenes to toluic acid, production of hydrogen sulfide and carbon disulfide, carbonylation of methanol to acetic acid, olefin synthesis, denitrogenation and desulfurization of coal tars, reductions with borohydrides, and nitrile syntheses, and such important reactions as the Fisher-Tropsch method for synthesizing liquid fuels and the hydroformylation process. Cobalt catalysts have also been used in the oxidation of poisonous hydrogen cyanide in gas masks and in the oxidation of carbon monoxide in automobile exhausts.

Although cobalt was not used in its metallic state until the twentieth century, the principal use of cobalt is as a metal in the production of alloys, chiefly high-temperature and magnetic types. Superalloys needed to stand high stress at high temperatures, as in jet engines and gas turbines, typically contain 20–65% cobalt along with nickel, chromium, molybdenum, tungsten, and other elements.

In parts of the world where soil and plants are deficient in cobalt, trace amounts of cobalt salts [for example, the chloride and nitrate of Co(II)] are added to livestock feeds and fertilizers to prevent serious wasting diseases of cattle and sheep, such as pining, a debilitating disease especially common in sheep. Symptoms of cobalt deprivation in animals include retarded growth, anemia, loss of appetite, and decreased lactation.

The principal biological role of cobalt involves corrin compounds (porphyrin-like macrocycles). The active forms contain an alkyl group (5′-deoxyadenosine or methyl) attached to the cobalt as well as four nitrogens from the corrin and a nitrogen from a heterocycle, usually 5,6-dimethylbenzimidazole. These active forms act in concert with enzymes to catalyze essential reactions in humans. However, the corrin compounds are not synthesized in the body; they must be ingested in very small quantities. Vitamin B12, with cyanide in place of the alkyl, prevents pernicious anemia but is itself inactive. The body metabolizes the vitamin into the active forms. Although the cobalt in corrins is usually Co(III), both Co(II) and Co(I) are involved in enzymic processes. Roughly one-third of all enzymes are metalloenzymes. Cobalt(II) substitutes for zinc in many of these to yield active forms. Such substitution of zinc may account, in part, for the toxicity of cobalt. See also Enzyme.


 

A mineral whose main function is in vitamin B12, although there are some cobalt-dependent enzymes. There is no evidence of cobalt deficiency in human beings, and no evidence on which to base estimates of requirements for inorganic cobalt. ‘Pining disease’ in cattle and sheep is due to cobalt deficiency (their intestinal micro-organisms synthesize vitamin B12) and it is a growth factor for some animals. Cobalt salts are toxic in excess, causing degeneration of the heart muscle, and habitual intakes in excess of 300 mg/day are considered undesirable.

 

An essential trace mineral. Cobalt is found in all cells but occurs in large quantities in bone marrow where it is required for the production of red blood cells. Until recently it was thought that cobalt in humans was found only as a constituent of vitamin B12 (cobalamin), but it is now known to have a role in some enzymes. Sources of cobalt include liver, lean meat, poultry, fish and milk. Recommended intakes have not been established, but excessive intakes (29.5 mg per day), which were used to treat certain anaemias, have proved toxic. High doses of cobalt salts may also contribute to heart disease. This was a problem in the 1950s when cobalt salts were added to beer in Belgium and Canada to retain the head.

 

Metallic chemical element, one of the transition elements, chemical symbol Co, atomic number 27. Widely dispersed in small amounts in many minerals and ores, this magnetic, silvery white metal with a faint bluish tinge is used mostly for special alloys (e.g., alnico, tool steel) with exacting applications. At valence 2 or 3 it forms numerous coordination complexes. One is vitamin B12 (cyanocobalamin; see vitamin B complex). Cobalt and its compounds are used in electroplating and colouring ceramics and glass and as lamp filaments, catalysts, a trace element in fertilizers, and paint and varnish driers. The pigment cobalt blue has a variable composition, roughly that of cobalt oxide plus alumina. A radioactive isotope of cobalt emits penetrating gamma rays that are used in radiation therapy.

For more information on cobalt, visit Britannica.com.

 

An essential trace element; it is a component of vitamin B12, essential for the production of red blood cells. It is required in very small amounts. Average daily intakes are about 0.3 mg. Very high doses (above 29 mg per day) have proved toxic. Sources include liver, lean meat, poultry, fish, and milk.

 
metallic chemical element; symbol Co; at. no. 27; at. wt. 58.9332; m.p. 1,495°C; b.p. about 2,870°C; sp. gr. 8.9 at 20°C; valence +2 or +3. Cobalt is a silver-white, lustrous, hard, brittle metal. It is a member of Group 9 of the periodic table. Like iron, it can be magnetized. It is similar to iron and nickel in its physical properties. The element is active chemically, forming many compounds, e.g., the series of cobaltous and cobaltic salts and the complex cobalt ammines derived from cobaltic salts and ammonia. Cobalt yellow, green, and blue are pigments of high quality that contain cobalt; another blue pigment, smalt, is made by powdering a fused mixture of cobalt oxide, potassium carbonate, and sand; these pigments are often used for coloring glass and ceramics. Cobalt chloride, used as an invisible ink, is almost colorless in dilute solution when applied to paper. Upon heating it undergoes dehydration and turns blue, becoming colorless again when the heat is removed and water is taken up. The element rarely occurs uncombined in nature but is often found in meteoric metal. It is a constituent of the minerals cobaltite and smaltite and of other ores, usually in association with other metals. Pure cobalt metal is prepared by reduction of its compounds by aluminum (the Goldschmidt process), by carbon, or by hydrogen. It is a component of several alloys, including the high-speed steels carboloy and stellite, from which very hard cutting tools are made. It is a component of some stainless steels, and of high-temperature alloys for use in jet engines. Alnico, an alloy of cobalt, aluminum, nickel, and other metals, is used to make high-strength, permanent magnets. As an element in the diet of sheep, cobalt prevents a disease called swayback and improves the quality of the wool. A radioactive isotope, cobalt-60 (with gamma ray emission 25 times that of radium), is prepared by neutron bombardment. It is used for cancer therapy and in industry for detecting flaws in metal parts. See hydrogen bomb. Cobalt was discovered in 1735 by Georg Brandt, a Swedish chemist.


 

A chemical element, atomic number 27, atomic weight 58.933, symbol Co. A component of vitamin B12.

  • c.-57 — a radioisotope of cobalt having a half-life of 270 days; used as a label for cyanocobalamin. Symbol 57Co.
  • c.-60 — a radioisotope of cobalt having a half-life of 5.27 years and a principal gamma ray energy of 1.33 MeV; used as a radiation therapy source. Symbol 60Co.
  • c. nutritional deficiency — causes anorexia and poor weight gain. Identification of the disease is based on chemical analysis of pasture and soil and biochemical analysis of animal tissues and fluids. Called also enzootic marasmus, Grand Traverse disease and other regional names.
  • c. poisoning — accidental overdosing with cobalt causes listlessness, weight loss and incoordination.
 
Wikipedia: cobalt


27 ironcobaltnickel
-

Co

Rh
Co-TableImage.png
General
Name, symbol, number cobalt, Co, 27
Chemical series transition metals
Group, period, block 94, d
Appearance metallic with gray tinge
Cobalt-sample.jpg
Standard atomic weight 58.933195(5) g·mol−1
Electron configuration [Ar] 3d7 4s2
Electrons per shell 2, 8, 15, 2
Density (near r.t.) 8.90 g·cm−3
Liquid density at m.p. 7.75 g·cm−3
Melting point 1768 K
(1495 °C, 2723 °F)
Boiling point 3200 K
(2927 °C, 5301 °F)
Heat of fusion 16.06 kJ·mol−1
Heat of vaporization 377 kJ·mol−1
Heat capacity (25 °C) 24.81 J·mol−1·K−1
Vapor pressure
P/Pa 1 10 100 1 k 10 k 100 k
at T/K 1790 1960 2165 2423 2755 3198
Atomic properties
Crystal structure hexagonal
Oxidation states 2, 3
(amphoteric oxide)
Electronegativity 1.88 (Pauling scale)
Ionization energies
(more)
1st: 760.4 kJ·mol−1
2nd: 1648 kJ·mol−1
3rd: 3232 kJ·mol−1
Atomic radius 135 pm
Atomic radius (calc.) 152 pm
Covalent radius 126 pm
Miscellaneous
Magnetic ordering ferromagnetic
Electrical resistivity (20 °C) 62.4 nΩ·m
Thermal conductivity (300 K) 100 W·m−1·K−1
Thermal expansion (25 °C) 13.0 µm·m−1·K−1
Speed of sound (thin rod) (20 °C) 4720 m/s
Young's modulus 209 GPa
Shear modulus 75 GPa
Bulk modulus 180 GPa
Poisson ratio 0.31
Mohs hardness 5.0
Vickers hardness 1043 MPa
Brinell hardness 700 MPa
CAS registry number 7440-48-4
Selected isotopes
Main article: Isotopes of cobalt
iso NA half-life DM DE (MeV) DP
56Co syn 77.27 d ε 4.566 56Fe
57Co syn 271.79 d ε 0.836 57Fe
58Co syn 70.86 d ε 2.307 58Fe
59Co 100% Co is stable with 32 neutrons
60Co syn 5.2714 years β- 2.824 60Ni
References

Cobalt (IPA: /ˈkəʊbɒlt/) is a hard, lustrous, silver-grey metal, a chemical element with symbol Co. It is found in various ores, and is used in the preparation of magnetic, wear-resistant, and high-strength alloys. Its compounds are used in the production of inks, paints, and varnishes.

Notable characteristics

Cobalt metal is a silver or grey ferromagnetic element of atomic number 27. The Curie temperature is of 1388 K with 1.6~1.7 Bohr magnetons per atom. In nature, it is frequently associated with nickel, and both are characteristic ingredients of meteoric iron. Mammals require small amounts of cobalt which is the basis of vitamin B12. Cobalt-60, an artificially produced radioactive isotope of cobalt, is an important radioactive tracer and cancer-treatment agent. Cobalt has a relative permeability two thirds that of iron. Metallic cobalt commonly presents a mixture of two crystallographic structures hcp and fcc with a transition temperature hcp→fcc of 722 K.

Common oxidation states of cobalt include +2 and +3, although compounds with oxidation state +1 are also well developed.

Applications

Cobalt blue glass
Enlarge
Cobalt blue glass


Radioisotopes of Cobalt

Main article: Isotopes of cobalt

Naturally occurring cobalt is "monoisotopic", i.e. only one isotope is stable: 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.

Cobalt Isotopes[1]
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

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's test.[2]

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

Cobalt-59 is used as a source in Mössbauer spectroscopy.

History

Cobalt compounds have been used for centuries to impart a rich blue color to glass, glazes, and ceramics. Cobalt has been detected in Egyptian sculpture and Persian jewelry from the third millennium BC, in the ruins of Pompeii (destroyed AD 79), and in China dating from the Tang dynasty (AD 618–907) and the Ming dynasty (AD 1368–1644)[3]. Cobalt glass ingots have been recovered from shipwrecks dating to the time of the Minoans [citation needed] (BC 2700-1450).

Swedish chemist George Brandt (1694–1768) is credited with isolating cobalt in 1735. He was able to show that cobalt was the source of the blue color in glass, which previously had been attributed to the bismuth found with cobalt.

During the 19th century, cobalt blue was produced at the Norwegian Blaafarveværket (70-80% of world production), led by the Prussian industrialist Benjamin Wegner.

In 1938, John Livingood and Glenn Seaborg discovered cobalt-60.

The word cobalt is derived from the German kobalt, from kobold meaning "goblin", a term used for the ore of cobalt by miners. The first attempts at smelting the cobalt ores to produce cobalt metal failed, yielding cobalt(II) oxide instead; not only that, but because of cobalt's curious affinity for arsenic, the primary ores of cobalt always contain arsenic, and upon smelting the arsenic oxidized into the highly toxic As4O6, which was breathed in by workers.

Biological role

Cobalt in small amounts is essential to many living organisms, including humans. Having 0.13 to 0.30 mg/kg of cobalt in soils markedly improves the health of grazing animals. Cobalt is a central component of the vitamin cobalamin, or vitamin B12.

Occurrence

Cobalt ore
Enlarge
Cobalt ore
Cobalt output in 2005
Enlarge
Cobalt output in 2005
World production trend
Enlarge
World production trend

Cobalt is not found as a native metal but generally found in the form of ores. Cobalt is usually not mined alone, and tends to be produced as a by-product of nickel and copper mining activities. The main ores of cobalt are cobaltite, erythrite, glaucodot, and skutterudite.

In 2005, the Democratic Republic of the Congo was the top producer of cobalt with almost 40% world share followed by Canada, Zambia, Russia, Brazil and Cuba, reports the British Geological Survey.

see also Category:Cobalt minerals

Compounds

There is a wide variety of cobalt compounds. The +2 and +3 oxidation states are most prevalent, however cobalt(I) complexes are also fairly common. Cobalt(II) salts form the red-pink [Co(OH2)6]2+ complex in aqueous solution. Adding excess chloride will also change the colour from pink to blue, due to the formation of [CoCl4]2-. Cobalt oxides are antiferromagnetic at low temperature: CoO (Neel temperature 291 K) and Co3O4 (Neel temperature: 40 K), which is analogous to magnetite (Fe3O4), with a mixture of +2 and +3 oxidation states. The oxide Co2O3 is probably unstable; it has never been synthesized. Other than Co3O4 and the brown fluoride CoF3 (which is instantly hydrolyzed in water), all compounds containing cobalt in the +3 oxidation state are stabilized by complex ion formation.

see also Category:Cobalt compounds

Precautions

Powdered cobalt in metal form is a fire hazard.

Cobalt compounds should be handled with care due to cobalt's slight toxicity.

60Co is a high-energy gamma ray emitter. Acute high-dose exposures to the gamma emissions, such as can occur when irradiation equipment is inadvertently diverted into scrap, can cause severe burns and death. Extended exposures increase the risk of morbidity or mortality from cancer.[4]

Nuclear weapon designs could intentionally incorporate 59Co, some of which would be activated in a nuclear explosion to produce 60Co. The 60Co, dispersed as nuclear fallout, creates what is sometimes called a dirty bomb or cobalt bomb, once predicted by physicist Leó Szilárd as being capable of wiping out all life on earth.

References & notes

  1. ^ Nuclides and Isotopes: Chart of the Nuclides, 16th Edition, by Edward Baum, Harold Knox, and Thomas Miller; Knolls Atomic Power Laboratory; 2002
  2. ^ JPNM Physics Isotopes
  3. ^ Encyclopedia Britannica Online.
  4. ^ The Juarez accident

External links

Wikimedia Commons has media related to:

 
Translations: Translations for: Cobalt

Dansk (Danish)
n. - kobolt

idioms:

  • cobalt blue    koboltblå

Nederlands (Dutch)
Kobalt

Français (French)
n. - cobalt

idioms:

  • cobalt blue    bleu-cobalt

Deutsch (German)
n. - (chem.) Kobalt

idioms:

  • cobalt blue    kobaltblau

Ελληνική (Greek)
n. - κοβάλτιο
adj. - του κοβαλτίου

idioms:

  • cobalt blue    ανοιχτογάλαζο(ς)

Italiano (Italian)
idioms:

  • cobalt blue    blu cobalto, cobalto

Português (Portuguese)
n. - cobalto (m) (Quím.)
adj. - de cobalto

idioms:

  • cobalt blue    azul (m) de cobalto

Русский (Russian)
кобальт

idioms:

  • cobalt blue    кобальтовая синь

Español (Spanish)
n. - cobalto

idioms:

  • cobalt blue    azul de cobalto

Svenska (Swedish)
n. - kobolt
adj. - kobolt-

中文(简体) (Chinese (Simplified))
钴, 由钴制的深蓝色, 钴类颜料

idioms:

  • cobalt blue    钴蓝色, 艳蓝色

中文(繁體) (Chinese (Traditional))
n. - 鈷, 由鈷制的深藍色, 鈷類顏料

idioms:

  • cobalt blue    鈷藍色, 豔藍色

한국어 (Korean)
n. - 원소기호 코발트, 코발트 색

日本語 (Japanese)
n. - コバルト

idioms:

  • cobalt blue    コバルトブルー

العربيه (Arabic)
‏(الاسم) مادة الكوبالت (صفه) كوبالتي, بلون الكوبالت‏

עברית (Hebrew)
n. - ‮קובלט‬


 
 

Join the WikiAnswers Q&A community. Post a question or answer questions about "cobalt" at WikiAnswers.

 

Copyrights:

Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2007. Published by Houghton Mifflin Company. All rights reserved.  Read more
Sci-Tech Encyclopedia. McGraw-Hill Encyclopedia of Science and Technology. Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved.  Read more
Food and Nutrition. A Dictionary of Food and Nutrition. Copyright © 1995, 2003, 2005 by A. E. Bender and D. A. Bender. All rights reserved.  Read more
Food and Fitness. Food and Fitness: A Dictionary of Diet and Exercise. Copyright © 1997, 2003 by Oxford University Press. All rights reserved.  Read more
Britannica Concise Encyclopedia. Britannica Concise Encyclopedia. © 2006 Encyclopædia Britannica, Inc. All rights reserved.  Read more
Sports Science and Medicine. The Oxford Dictionary of Sports Science & Medicine. Copyright © Michael Kent 1998, 2006, 2007. All rights reserved.  Read more
Columbia Encyclopedia. The Columbia Electronic Encyclopedia, Sixth Edition Copyright © 2003, Columbia University Press. Licensed from Columbia University Press. All rights reserved. www.cc.columbia.edu/cu/cup/  Read more
Veterinary Dictionary. Saunders Comprehensive Veterinary Dictionary 3rd Edition. Copyright © 2007 by D.C. Blood, V.P. Studdert and C.C. Gay, Elsevier. All rights reserved.  Read more
Wikipedia. This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Cobalt" Read more
Translations. Copyright © 2007, WizCom Technologies Ltd. All rights reserved.  Read more

Search for answers directly from your browser with the FREE Answers.com Toolbar!  
Click here to download now. 

Get Answers your way! Check out all our free tools and products.

On this page:   E-mail   print Print  Link  

 

Keep Reading

Mentioned In: