cobalt (Co) | chemical element | Britannica.com chemical element Cobalt (Co), chemical element , ferromagnetic metal of Group 9 (VIIIb) of the periodic table , used especially for heat-resistant and magnetic alloys. Cobalt. Ben Mills The metal was isolated (c. 1735) by a Swedish chemist, Georg Brandt , though cobalt compounds had been used for centuries to impart a blue colour to glazes and ceramics. Cobalt has been detected in Egyptian statuettes and Persian necklace beads of the 3rd millennium bce, in glass found in the Pompeii ruins, and in China as early as the Tang dynasty (618–907 ce) and later in the blue porcelain of the Ming dynasty (1368–1644). The name kobold was first applied (16th century) to ores thought to contain copper but eventually found to be poisonous arsenic-bearing cobalt ores. Brandt finally determined (1742) that the blue colour of those ores was due to the presence of cobalt.

Occurrence, properties, and uses Cobalt, though widely dispersed, makes up only 0.001 percent of Earth’s crust. It is found in small quantities in terrestrial and meteoritic native nickel-iron, in the Sun and stellar atmospheres, and in combination with other elements in natural waters, in nodules beneath the oceans, in soils, in plants and animals, and in such minerals as cobaltite , linnaeite, skutterudite , smaltite , heterogenite, and erythrite . Little cobalt ore is mined for the cobalt content. Traces of cobalt are present in many ores of iron , nickel , copper, silver , manganese , zinc , and arsenic , from which it is often recovered as a by-product. Complex processing is required to concentrate and extract from these ores. China, Congo, Finland, Zambia , and Australia became the world’s leading producers of cobalt by the early 21st century. Cobalt is a trace element essential in the nutrition of ruminants (cattle, sheep) and in the maturation of human red blood cells in the form of vitamin B 12, the only vitamin known to contain such a heavy element.

Similar Topics cesium (Cs) Polished cobalt is silver-white with a faint bluish tinge. Two allotropes are known: the close-packed-hexagonal structure stable below 417 °C (783 °F) and the face-centred-cubic, stable at high temperatures. It is ferromagnetic up to 1,121 °C (2,050 °F, the highest known Curie point of any metal or alloy) and may find application where magnetic properties are needed at elevated temperatures. Cobalt is one of the three metals that are ferromagnetic at room temperature . It dissolves slowly in dilute mineral acids, does not combine directly with either hydrogen or nitrogen , but will combine, on heating, with carbon , phosphorus , or sulfur . Cobalt is also attacked by oxygen and by water vapour at elevated temperatures, with the result that cobaltous oxide , CoO (with the metal in the +2 state), is produced. Natural cobalt is all stable isotope cobalt-59, from which the longest lived artificial radioactive isotope cobalt-60 (5.3-year half-life) is produced by neutron irradiation in a nuclear reactor.

Gamma radiation from cobalt-60 has been used in place of X rays or alpha rays from radium in the inspection of industrial materials to reveal internal structure, flaws, or foreign objects; in cancer therapy; in sterilization studies; and in biology and industry as a radioactive tracer. It is in turn being replaced in both industrial and medical radiology by cesium-137 because of the long (30-year) half-life of the latter. Most of the cobalt produced is used for special alloys . A relatively large percentage of the world’s production goes into magnetic alloys such as the Alnicos for permanent magnets. Sizable quantities are utilized for alloys that retain their properties at high temperatures and superalloys that are used near their melting points (where steels would become too soft). Cobalt is also employed for hard-facing alloys, tool steels, low-expansion alloys (for glass-to-metal seals), and constant-modulus (elastic) alloys (for precision hairsprings). Cobalt is the most satisfactory matrix for cemented carbides. Ringling Bros. Folds Its Tent Both Co2+ and Co3+ form numerous coordination compounds, or complexes. Co3+ forms more known complex ions than any other metal except platinum .

The coordination number of the complexes is generally six. Cobalt forms two well-defined binary compounds with oxygen: cobaltous oxide, CoO, and tricobalt textroxide, or cobalto-cobaltic oxide, Co3O4. The latter contains cobalt in both +2 and +3 oxidation states and constitutes up to 40 percent of the commercial cobalt oxide used in the manufacture of ceramics, glass, and enamel and in the preparation of catalysts and cobalt metal powder. One of the more important salts of cobalt is the sulfate CoSO4, which is employed in electroplating , in preparing drying agents, and for pasture top-dressing in agriculture. Other cobaltous salts have significant applications in the production of catalysts, driers, cobalt metal powders, and other salts. Cobaltous chloride (CoCl2∙6H2O in commercial form), a pink solid that changes to blue as it dehydrates, is utilized in catalyst preparation and as an indicator of humidity. Cobaltous phosphate, Co3(PO4)2∙8H2O, is used in painting porcelain and colouring glass.

Element Properties Cobalt, Chemical Element - reaction, water, uses, elements, metal, gas, number, name PRONUNCIATION CO-balt The United States has to import all the cobalt it uses. The most important application is in the production of superalloys. Superalloys primarily consist of iron, cobalt, or nickel, with small amounts of other metals, such as chromium, tungsten, aluminum, and titanium. Superalloys are resistant to corrosion (rusting) and retain their properties at high temperatures. Superalloys are used in jet engine parts and gas turbines. Discovery and naming Cobalt dyes have been used for centuries. Craftsmen used materials from the earth to color glass, pottery, glazes, and other materials. Cobalt minerals were especially prized for their rich blue color. The word cobalt may have been first used near the end of the fifteenth century. In German, the word Kobold means "goblin" or "evil spirit." The term was used by miners to describe a mineral that was very difficult to mine and was damaging to their health. When the mineral was heated, it gave off an offensive gas that caused illness.

The gas that affected the miners was arsenic trioxide (As 4 O 6 ), which often occurs with cobalt in nature. At first, chemists were skeptical about Brandt's claims of a new element, but he continued his research on the mineral. He showed that its compounds were a much deeper blue than copper compounds. (Copper and cobalt compounds had long been confused with each other.) Eventually, Brandt was given credit for the discovery of the element. The name chosen was a version of the original German term, Kobold. Physical properties Cobalt is a hard, gray metal that looks much like iron and nickel. It is ductile, but only moderately malleable. Ductile means capable of being drawn into thin wires. Malleable means capable of being hammered into thin sheets. Cobalt is one of only three naturally occurring magnetic metals. The other two are iron and nickel. The magnetic properties of cobalt are even more obvious in alloys. An alloy is made by melting and mixing two or more metals. The mixture has properties different from those of the individual metals.

The melting point of cobalt metal is 1,493°C (2,719°F), and the boiling point is about 3,100°C (5,600°F). The density is 8.9 grams per cubic centimeter. Chemical properties Cobalt is a moderately reactive element. It combines slowly with oxygen in the air, but does not catch fire and burn unless it is in a powder form. It reacts with most acids to produce hydrogen gas. It does not react with water at room temperatures. Cobalt samples. Occurrence in nature Cobalt is a relatively abundant element at about 10 to 30 parts per million. This places it in the upper third of elements according to their abundance in the Earth's crust. The most common ores of cobalt are cobaltite, smaltite, chloranthite, and linnaeite. The major suppliers of cobalt in the world are Zambia, Canada, Russia, Australia, Zaire, and Cuba. No cobalt is mined in the United States.

The word cobalt, from the German word Kobold , meaning "goblin" or "evil spirit," was used by miners to describe a mineral that was very difficult to mine and was damaging to their health. Isotopes There is only one naturally occurring isotope of cobalt, cobalt-59. Isotopes are two or more forms of an element. Isotopes differ from each other according to their mass number. The number written to the right of the element's name is the mass number. The mass number represents the number of protons plus neutrons in the nucleus of an atom of the element. The number of protons determines the element, but the number of Cobalt's use in magnetic alloys is critical for devices that must hold a magnetic field, such as electric motors. neutrons in the atom of any one element can vary. Each variation is an isotope. Ten radioactive isotopes of cobalt are known also. A radioactive isotope is one that breaks apart and gives off some form of radiation. Radioactive isotopes are produced when very small particles are fired at atoms. These particles stick in the atoms and make them radioactive. Cobalt-60 is one of the most widely used of all radioactive isotopes.

In medicine, it is used to find and treat diseases. For example, it is used in a test known as the Schilling test. This test is a method for determining whether a person's body is making and using vitaminB 12 properly. Two other isotopes of cobalt, cobalt-57 and cobalt-58, are used for the same purpose. Cobalt-60 is also used to treat cancer. The radiation given off by the isotope kills cancer cells. The isotope has been used for nearly 50 years to treat various forms of cancer. Erbium is used in optical fibers, very thin pieces of glass or plastic used in the communications industry. Carbon reacts with oxygen by burning in air. Solid carbon dioxide is most commonly known as dry ice. Chromium comes from the Greek word for color. These bottles contain different colored chromium compounds. Calcium carbonate can be found in coral. A laboratory vessel holds the solid, liquid, and gas states of bromine. This is the top view of a particle accelerator, or atom smasher. The instrument has been used to convert very small particles and atoms into new elements, such as californium. The magnets in the accelerator consist of boron alloys.

Bismuth crystals. Cobalt (Co) - Chemical properties, Health and Environmental effects - 0.28 V ( Co2+/ Co ) ; +1.84 V ( Co3+/ Co2+ ) Discovered by George Brandt in 1737 Cobalt Cobalt is a hard ferromagnetic, silver-white, hard, lustrous, brittle element. It is a member of group VIII 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. Cobalt is stable in air and unaffected by water, but is slowly attacked by dilute acids. Applications Cobalt is used in many alloys (superalloys for parts in gas turbine aircrafr engines, corrosion resistant alloys, high-speed steels, cemented carbides), in magents and magnetic recording media, as catalysts for the petroleum and chemical industries, as drying agents for paints and inks. Cobalt blue is an important part of artists' palette and is used bu craft workers in porcelain, pottery, stained glass, tiles and enamel jewellery.

The radioactive isotopes, cobalt-60, is used in medical treatment and also to irradiate food, in order to preserve the food and protect the consumer. Cobalt in the enviroment Most of the Earth's cobalt is in its core. Cobalt is of relatively low abundance in the Earth's crust and in natural waters, from which it is precipitated as the highly insoluble cobalt sulfine CoS. Although the average level of cobalt in soils is 8 ppm, there are soils with as little as 0.1 ppm and others with as much as 70 ppm. In the marine environment cobalt is needed by blue-green algae (cyanobacteria) and other nitrogen fixing organisms. Cobalt is not found as a free metal and is 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. The world's major producers of cobalt are the Democratic Republic of the Congo, mainland China, Zambia, Russia and Australia.

It is also found in Finland, Azerbaijan, and Kazakhstan. World production is 17.000 tonnes per year. Health effects of cobalt As cobalt is widely dispersed in the environment humans may be exposed to it by breathing air, drinking water and eating food that contains cobalt. Skin contact with soil or water that contains cobalt may also enhance exposure. Cobalt is not often freely available in the environment, but when cobalt particles are not bound to soil or sediment particles the uptake by plants and animals is higher and accumulation in plants and animals may occur. Cobalt is beneficial for humans because it is a part of vitamin B12 , which is essential for human health. Cobalt is used to treat anaemia with pregnant women, because it stimulates the production of red blood cells. The total daily intake of cobalt is variable and may be as much as 1 mg, but almost all will pass through the body unadsorbed, except that in vitamine B12. However, too high concentrations of cobalt may damage human health. When we breathe in too high concentrations of cobalt through air we experience lung effects, such as asthma and pneumonia. This mainly occurs with people that work with cobalt.

When plants grow on contaminated soils they will accumulate very small particles of cobalt, especially in the parts of the plant we eat, such as fruits and seeds. Soils near mining and melting facilities may contain very high amounts of cobalt, so that the uptake by humans through eating plants can cause health effects. Health effects that are a result of the uptake of high concentrations of cobalt are: - Vomiting and nausea - Heart problems - Thyroid damage Health effects may also be caused by radiation of radioactive cobalt isotopes. This can cause sterility, hair loss, vomiting, bleeding, diarrhoea, coma and even death. This radiation is sometimes used with cancer-patients to destroy tumors. These patients also suffer from hair loss, diarrhea and vomiting. Cobalt dust may cause an asthma-like disease with symptoms ranging from cough, shortness of breath and dyspnea to decreased pulmonary function, nodular fibrosis, permanent disability, and death. Exposure to cobalt may cause weight loss, dermatitis, and respiratory hypersensitivity. LD 50 (oral, rat)- 6171 mg/kg.

(LD50 = Lethal dose 50 = Single dose of a substance that causes the death of 50% of an animal population from exposure to the substance by any route other than inhalation. LD50 is usually expressed as milligrams or grams of material per kilogram of animal weight (mg/kg or g/kg).) Carcinogenicity- International Agency for Research on Cancer (IARC) haslisted cobalt and cobalt compounds within group 2B (agents which are possibly carcinogenic to humans). ACGIH has placed cobalt and inorganic compounds in category A3 (Experimental animal carcinogen- the agent is carcinogenic in experimental animals at a relatively high dose, by route(s), histologic type(s), or by mechanism(s) that are not considered relevant to worker exposure.) Cobalt has been classified to be carcinogenic to experimental animals by the Federal Republic of Germany. cobalt, chemical element Encyclopedia > Science and Technology > Chemistry > Compounds and Elements cobalt cobalt, 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. The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press.

All rights reserved. Cobalt - Element information, properties and uses | Periodic Table Chemistry in its element: cobalt (Promo) You're listening to Chemistry in its element brought to you by Chemistry World, the magazine of the Royal Society of Chemistry. (End promo) Chris Smith Hello - beauty, blue glass, B12 and the best magnets that money can buy. So why is this week's element named after a goblin? Sarah Staniland I always find the question 'what's your favourite element' a difficult one. There are several front runners for vastly varying reasons; however, always a top contender has to be cobalt because it excels in several important character traits: Cobalt has amazing beauty and strength, as well as great cooperation. All together a highly useful metal. Before I even thought about the chemistry of colour I developed a love for blue glass, something I still collect to this day. Only after studying the transition metal chemistry did I realise that this beautiful blue colour comes from cobalt. Cobalt chloride in fact. However, as far as colours go, cobalt has a few more strings to its bow than just this wonderful blue.

Cobalt can also colour glass green, while the hydrated form of cobalt chloride is a beautiful deep rose colour. As you can imagine this colour change due to the presence of water is highly useful, warranting cobalt chloride an ideal moisture indicator. The array of beautiful colours that cobalt produces were never more prevalent to me than when I went to the cobalt mining region called the Copperbelt in Zambia. In this area the huge multicoloured cobalt minerals deposits tower high, with the shores of dams and streams coloured deep rose with silvery blue veins running through. Cobalt it is not found pure in Nature but found in sulphur minerals and usually associated with other transition metals. As you can probably guess from the name of the region in Zambia - the Copperbelt, cobalt is mined as a secondary product to copper that is dominant in the ore of this region. Because of this cobalt is normally recovered from the waste of the primary metal extraction. However these mining hotspots are not the only places on the Earth where high concentrations of cobalt can be found. A huge reserve of several transition metals (including cobalt) can be found in strange nodules on the floors of the deepest oceans.

The nodules are manganese minerals that take millions of years to form, and there are many tonnes of cobalt present in this form. So you can see that cobalt is never found alone but always palled up with other transition metals in their ores, mainly copper and nickel. In fact cobalt metal was not isolated and purified until as late as 1735 by the Swedish scientist G. Brandt. Cobalt can also sometimes be found in mixed arsenic ores, and it is cobalt's association with arsenic that gives it its name. The word cobalt comes from the German "Kobolds" which means goblin or trouble maker. It was so called in this early mining region because it was very difficult to smelt without oxidising and smelting would release the associated arsenic vapours which would lead to pretty troublesome or even deadly processing conditions for the worker. The Kobolds were blamed and the name stuck. With the exception of the mining region, cobalt is not very abundant, with only trace amounts in the Earths crust (about 2500 times less than iron). However, it is a metal that is essential for life in the trace amounts.

Cobalt is the metal at the centre of vitamin B12 which helps regulate cell development and therefore DNA and energy production in the body. Cobalt has been known and used by people for its beautiful colouring and pigment properties as far back as 2500BC. Egyptian cobalt blue paints and Prussian cobalt oxide necklaces have been dated back to this time while cobalt glass has been found in a Greek vase dated at 100 BC. Cobalt was also used to colour glass in the Chinese Tang dynasty from 618 AD. In fact all the way up until the beginning of the 20th century people have only really exploited cobalt for its beautiful colour. However cobalt is not just a pretty face. Cobalt is a lustrous very hard silvery metal belonging to a group called the "transition metals". It is one of only 3 ferromagnetic transition elements along with iron and nickel. As a metal it is very mechanically hard and tough, and it has a very high melting point (hence the smelting problems) and also remains magnetic to the highest temperature of all the magnetic elements.

When cobalt is combined with other metals its strength allow a range of super alloys to be created. In particular, cobalt's very high melting point and mechanical strength at high temperatures has seen its extensive use in what is termed 'superalloys'. These are alloys that retain mechanical strength at high temperatures. Because of its impressive properties cobalt is an important component in wear resistant and corrosive resistant alloys. And cobalt alloys and coatings are seen everywhere from drills to saws, from aircraft turbines to prosthetic bone replacements. The fact that cobalt is magnetic has also been exploited with the Japanese invention of cobalt magnetic steel where adding cobalt to steel vastly increases the magnetic hardness. Just a few years after that in the 1930s saw the pivotal invention of Alnico magnets, which as the name suggests, are composed of aluminium, nickel and cobalt. The fact that cobalt retains its magnetism up to high temperatures is also a very favourable trait when the addition of cobalt to a magnetic material can improve its properties at high temperatures. More recently the creation of rare-earth magnets have given us much stronger, harder, permanent magnets than Alnico magnets.

One such magnetic material, samarium cobalt retains its magnetism up to 800°C. Because it is magnetically and mechanically hard up to very high temperatures, it has found uses in high-speed motors and turbo machinery. More recently cobalt has a major use in newer batteries, magnetic particles for recording and storage information in magnetic tapes and hard drives. So cobalt; giving joy in an array of beautiful colours, but also ultra strong, hard and magnetic. Cobalt is never alone, it is found associated with different metals in their ore and has its best mechanical properties when palled up with others. Chris Smith Emphasising the importance, of course, of teamwork. That was Sarah Staniland with the story of Cobalt - she's based at the University of Leeds. Next week it's the turn of the stuff that amongst other things makes Parker pen nibs write so nicely, but if you haven't heard of it before, then you're probably in good company. Jonathan Steed Stop the proverbial "man in the street" and ask him what ruthenium is and the chances are he won't be able to tell you.

Compared to the "sexier elements" that are household names like carbon and oxygen, ruthenium is, frankly, a bit obscure. In fact even if your man in the street was wearing a lab coat and walking on a street very close to a university chemistry department he might still be a bit ignorant about this mysterious metal. It wasn't always that way, though. Chris Smith And you can hear how ruthenium rose to prominence with Jonathan Steed on next week's Chemistry in its Element. I'm Chris Smith, thank you for listening and goodbye. (Promo) Chemistry in its element is brought to you by the Royal Society of Chemistry and produced by thenakedscientists.com . There's more information and other episodes of Chemistry in its element on our website at chemistryworld.org/elements . (End promo) CDC - Cobalt - NIOSH Workplace Safety and Health Topic Other Related Resources Introduction Cobalt is a hard, lustrous, gray metal, and chemical element with symbol Co and atomic number 27. Cobalt is a naturally occurring element found in rocks, soil, water, plants, animals and humans.

Moreover, it is a part of vitamin B12, which is necessary for neurological function, brain function, and the formation of blood. Cobalt-containing products include corrosion and heat-resistant alloys, hard metal (cobalt-tungsten-carbide alloy), magnets, grinding and cutting tools, pigments, paints, colored glass, surgical implants, catalysts, batteries, and cobalt-coated metal (from electroplating). Radioactive isotopes of cobalt provide the following diagnostic and treatment tools: medical radioisotopes, industrial radiography (analysis of weld integrity), food irradiation, and concrete density measurements. In the United States, more than a million workers are potentially exposed to cobalt and its compounds, with the greatest exposure in mining processes, cemented tungsten-carbide industry, cobalt powder industry, and alloy production industry. In addition, workers are exposed to cobalt in the production, processing, and use of hard metal; and the grinding and sharpening of steel tools with hard metal abrasives. Chronic exposure to cobalt-containing hard metal (dust or fume) can result in a serious lung disease called "hard metal lung disease", which is a type of pneumoconiosis (lung fibrosis).

Furthermore, inhalation of cobalt particles can cause respiratory sensitization, asthma, shortness of breath, and decreased pulmonary function. Even though the primary route of occupational exposure to cobalt is the respiratory tract, skin contact is also important because dermal exposures to hard metal and cobalt salts can result in significant systemic uptake. Sustained exposures can cause skin sensitization, which may result in eruptions of contact dermatitis. NIOSH Resources NIOSH Pocket Guide to Chemical Hazards Exposure limits, Respirator Recommendations, First Aid, more... The Pocket Guide is a source of general industrial hygiene information on several hundred chemicals/classes found in the work environment. Key data provided for each chemical/substance includes name (including synonyms/trade names), structure/formula, CAS/RTECS Numbers, DOT ID, conversion factors, exposure limits, IDLH, chemical and physical properties, measurement methods, personal protection, respirator recommendations, symptoms, and first aid. Cobalt CAS No.

7440-48-4 Cobalt (element) | Article about Cobalt (element) by The Free Dictionary Cobalt (element) | Article about Cobalt (element) by The Free Dictionary Related to Cobalt (element): Element 27 Cobalt (kō`bôlt), town (1991 pop. 1,470), E Ont., Canada, NE of Sudbury, near Lake Timiskaming. Once a center for cobalt and silver mining, the area is now economically depressed. The town has a mining museum and an annual Miner's Festival. cobalt, metallic chemical element; symbol Co; at. no. 27; at. wt. 58.9332; m.p. 1,495&degC;; b.p. about 2,870&degC;; sp. gr. 8.9 at 20&degC;; valence +2 or +3. Cobalt is a silver-white, lustrous, hard, brittle metal. It is a member of Group 9 of the periodic table periodic table, chart of the elements arranged according to the periodic law discovered by Dmitri I.

Mendeleev and revised by Henry G. J. Moseley. In the periodic table the elements are arranged in columns and rows according to increasing atomic number (see the table entitled ..... Click the link for more information. . 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 cobaltite , opaque, silver-white, sometimes reddish or grayish mineral of the pyrite group, a compound of cobalt, arsenic, and sulfur, CoAsS. It occurs in crystals of the cubic system, also in compact to granular masses. ..... Click the link for more information. and smaltite smaltite , opaque tin-white to steel-gray mineral of the pyrite group, a compound of cobalt and arsenic. It occurs in massive form, occasionally in crystals (cubes) of the isometric system. It is an important ore of cobalt and is found in Saxony, Norway, Sweden, and Ontario. ..... Click the link for more information. 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 hydrogen bomb or H-bomb, weapon deriving a large portion of its energy from the nuclear fusion of hydrogen isotopes. In an atomic bomb, uranium or plutonium is split into lighter elements that together weigh less than the original atoms, the remainder of the mass ..... Click the link for more information. . Cobalt was discovered in 1735 by Georg Brandt, a Swedish chemist. Cobalt a city in Canada, in southeastern Ontario Province on the western shore of Lake Témiscaming. Population, 2,200 (1971). Cobalt has a railroad station and is a center for cobalt and silver mining.

The city arose in 1903 and was at its height in 1915, when its population reached 30,000. Mining began to decline in 1929 and ceased entirely from 1935 to 1946, being resumed in 1950 with the increased demand for silver and cobalt. Cobalt (Latin, cobaltum), Co, a chemical element of the first triad of Group VIII in the Mendeleev periodic system. Atomic number, 27; atomic weight, 58.9332. A heavy silver metal shot through with pink. There is one naturally occurring stable isotope, 59Co; 60Co is the most important artificially produced radioactive isotope. Historical information. Cobalt oxide was used in ancient Egypt, Babylonia, and China as a blue coloring for glass and enamel. Zaffer, a gray earthy mass produced by roasting certain ores called cobold ores, began to be used for this purpose in western Europe in the 16th century.

These ores released copious toxic fumes when roasted, and it was impossible to smelt out the metal from the roasting products. Medieval miners and metallurgists believed this to be the pranks of mythical beings called cobolds (German Kobold, “sprite” or “gnome”). In 1735 the Swedish chemist G. Brant produced a metal that he named cobold regulus by heating a mixture of zaffer with carbon and flux in a blast furnace. The name was soon changed to “cobolt” and then “cobalt.” Occurrence in nature. The content of cobalt in the lithosphere is 1.8 × 10-3 percent by weight. In the earth’s crust it migrates in magma, as well as in hot and cold waters. It accumulates primarily in the upper mantle during magmatic differentiation; its average content in hyperbasic rocks is 2 × 10-2 percent. The formation of “liquation” deposits of cobalt ore is related to magmatic processes. Hydrothermal cobalt deposits are formed as a result of ore concentration in hot subterranean waters, where cobalt is bonded to nickel, arsenic, sulfur, and copper.

Approximately 30 cobalt minerals are known. Cobalt is mainly scattered throughout the biosphere; however, cobalt deposits form in regions where plants that are cobalt concentrators grow. Marked differentiation of cobalt is observed in the upper parts of the earth’s crust: the average cobalt content in clay and shale is 2 × 10-3 percent; in sandstones, 3 × 10-5 percent; and in limestones, 1 × 10-5 percent. The sandy soils of wooded areas are highly deficient in cobalt. Very little cobalt is found in surface waters; the world’s oceans contain only 5 × 10 -8 percent cobalt. Since it is a poor water migrant, cobalt is readily converted into sediment, which is absorbed by manganese hydroxides, clay, and other highly disperse minerals. Physical and chemical properties.

At ordinary temperatures (and up to 417°C) the crystal lattice of cobalt is close-packed hexagonal, with lattice constants a = 2.5017 angstroms (Å) and c = 4.614 Å; at higher temperatures the lattice becomes facecentered cubic (a = 3.5370 Å). Atomic radius, 1.25 Å; ion radii, Co2+ 0.78 Å and Co3+ 0.64 Å; density, 8.9 g/cm3 (at 20°C); melting point, 1493°C; boiling point, 3100°C.

Specific heat, 0.44 kilojoules per (kg·°K), or 0.1056 calories per (g·°C); thermal conductivity, 69.08 watts per (m·°K), or 165 calories per (cm·sec·°C) for 0°–100°C; specific electrical resistance, 5.68 × 10-8 ohm·m, or 5.68 × 10-6 ohm·cm (at 0°C). Cobalt is ferromagnetic and maintains its ferromagnetism from low temperatures up to the Curie point, Ⓗ= 1121°C. The mechanical properties of cobalt depend on the methods of mechanical and thermal treatment used. Tensile strength, 500 meganewtons per sq m (MN/m2), or 50 kilograms-force per sq mm (kgf/mm2), for forged and annealed cobalt; 242–260 MN/ m2 for cast cobalt; and 700 MN/m2 for cobalt wire.

Brinell hardness, 2.8 GN/m2, or 280 kgf/mm2, for cold-worked metal; 3.0 GN/m2 for metal precipitated by electrolysis; and 1.2–1.3 GN/m2 for annealed cobalt. The configuration of the outer electron shells of a cobalt atom is 3d74s2. In compounds cobalt exhibits alternating valence. In simple compounds, Co (II) has the highest degree of stability, and Co (III) is most stable in complex compounds. Only a few complex compounds of Co (I) and Co (IV) have been produced. Cobalt is resistant to water and air at room temperature. Finely crushed cobalt, which is produced by reduction of cobalt oxide with hydroxide at 250°C (pyrophoric cobalt), undergoes spontaneous combustion upon exposure to air and is converted into CoO. Compacted cobalt begins to oxidize in air at temperatures above 300°C, and it dissociates water vapor at red heat: Co + H2O = CoO + H 2.

Cobalt combines readily with halogens upon heating to form halides, CoX2. When heated, cobalt reacts with sulfur, selenium, phosphorus, arsenic, antimony, carbon, silicon, and boron; however, the composition of the compounds produced sometimes does not satisfy the valence states mentioned above (for example, Co2P, Co2AS, CoSb2, Co3C, and CoSi3). Cobalt is dissolved slowly in dilute hydrochloric and sulfuric acids, with the liberation of hydrogen and the formation of cobalt chloride, CoCl2, and cobalt sulfate, CoSO4, respectively. Cobalt dissolves in dilute nitric acid, releasing nitric oxide and forming a nitrate, Co(NO3)2. Concentrated HNO3 passivates cobalt. The salts of Co (II) mentioned above are readily soluble in water [at 25°C, 100 g H2O dissolves 52.4 g CoCl2, 39.3 g CoSO4, and 136.4 g Co(NO3)2].

Caustic alkalies precipitate a blue hydroxide, Co(OH)2, from Co2+ salt solutions; the hydroxide gradually turns brown as it undergoes oxidation by atmospheric oxygen into Co(OH)3. Upon heating to 400°–500°C in the presence of oxygen, CoO is transformed into a black oxide, Co3O4, or CoO·Co2O3 (a spinel compound). A compound of this type, such as CoAl2O4or blue CoO·Al2O3 (cobalt blue, or Thénard’s blue, discovered by L. J. Thénard in 1804), is produced upon calcination of a mixture of CoO and Al2O3 at a temperature of about 1000°C. Only a few simple Co (III) compounds are known to exist. The brown fluoride CoF3 is formed by treating Co or CoCl2 powder with fluorine at 300°–400°C. Complex compounds of Co (III) are highly stable and can be produced easily.

For example, KNO 2 precipitates the yellow, poorly soluble product potassium hexanitrocobaltate (III), K3 [Co(NO2)6], from solutions of Co (II) salts containing CH3 COOH. Cobaltammines (formerly known as cobaltiacs), which are complex Co (III) compounds containing ammonia or certain organic amines, are extremely abundant. Preparation and use. Cobalt minerals are rare and do not form any significant accumulations of ore. Nickel ores, which contain cobalt as an impurity, are the main source for the industrial extraction of cobalt. The processing of these ores is extremely complex, and the method used depends on the composition of the ore. A solution of cobalt chlorides and nickel chlorides, containing the impurities Cu2+, Pb2+, Bi3+, is obtained as a final result. Copper, lead, and bismuth sulfides are precipitated by H2S, after which Fe (II) is converted into Fe (III) by the passage of chlorine; Fe(OH)3 and CaHAsO4 are subsequently precipitated by the addition of CaCO3.

Cobalt is separated from nickel by the reaction 2CoCl2 + NaCIO + 4NaOH + H2O = 2Co(OH)3↓ + 5NaCl. Almost all the nickel remains in the solution. The black residue Co(OH)3 is calcined to remove water, and the resultant oxide Co3O4 is reduced with hydrogen or carbon. Metallic cobalt that contains up to 2–3 percent impurities (nickel, iron, copper, and so on) can be purified by electrolysis. Cobalt is used primarily in the form of alloys based on it (cobalt alloys), as well as alloys based on other metals in which cobalt is the alloying element. Cobalt alloys are used as heat-resistant and scaling-resistant materials and in the manufacture of permanent magnets and cutting tools. Powdered cobalt and Co3O4 are used as catalysts. The fluoride CoF3 is used as a strong fluorinating agent; Thénard’s blue and particularly the silicate of cobalt and potassium are used as paints in the ceramics and glass-making industries.

Cobalt salts are used as trace-element fertilizers in agriculture, as well as in fodder for fattening animals. S. A. P OGODIN The most important artificially radioactive cobalt isotope is 60Co, with half-life T½ = 5.27 years. It is widely used as a gamma emitter in gamma-ray flaw detection. In medicine, 60Co is used primarily in radiation therapy on tumors, as well as for sterilizing medicines. It also serves to destroy insects in grain and fruits and is used in preserving food products. Other radioactive isotopes—for example, 56Co (T½ = 77 days), 57Co (270 days), and 58Co (72 days), which are less harmful because of their short half-life—are used as isotope tracers in the study of metabolism, particularly in studying the distribution of cobalt in the bodies of animals (for example, the permeability of the placenta was studied with the aid of radioactive cobalt). Cobalt in the organism. Cobalt, which is always present in animal and plant tissues, participates in metabolic processes.

The cobalt content in the bodies of animals is related to the cobalt content in food plants and soils. The average cobalt concentration in plants growing in pastures and meadows is 2.2 × 10-5 to 4.5 × 10-5 percent dry weight. Cobalt accumulation in leguminous plants exceeds that in herbaceous and oleraceous plants. Because of the great ability of seaweed to accumulate cobalt its cobalt content is virtually the same as that in land plants, although there is considerably less cobalt in seawater than in the soil. The daily cobalt requirement for humans is approximately 7–15 micrograms and is satisfied by its intake with food. The cobalt requirement for animals depends on their species, age, and productivity. Ruminants require the most cobalt, since it is essential for the development of the symbiotic microflora in the stomach (primarily in the rumen). The daily cobalt requirement for milch cows is 7–20 mg; for sheep, about 1 mg.

In cases of cobalt-deficient diets, the productivity of animals decreases, metabolism and hematopoiesis are disrupted, and ruminants suffer from an endemic disease, cobalt deficiency. The biological activity of cobalt is determined by its participation in the structuring of the vitamin B12 molecule and its coenzymatic forms and of the enzyme transcarboxylase. Cobalt is necessary for the activity of several enzymes. It affects protein metabolism, the synthesis of nucleic acids, carbohydrate and fat metabolism, and oxidation-reduction reactions in animals. Cobalt is a powerful activator of hematopoiesis and the synthesis of erythropoietins. It takes part in the enzyme systems of symbiotic bacteria that fix atmospheric nitrogen. Cobalt also stimulates growth, development, and productivity of leguminous and other plants. I

Question: The chemical element cobalt is a?
Answer: Metal