Introduction to Cobalt
The element cobalt, located in Group 9 on the Periodic Table, falls into the transition metal category. This metal occurs naturally in air, water, soil, rocks, plants, and animals. Cobalt appears solid with a silver-white luster and bluish tinge, and it remains brittle at room temperature.
It’s an essential trace element in the body, and like iron it can be magnetized. Cobalt’s uses are quite diverse, extending to turbine and aircraft engines, the petroleum and chemical industries, and drying agents in paints and inks. Even one of its radioactive isotopes, Co-60, has proven key to the irradiation of many food products.
10 Interesting & Fun Facts About Cobalt
1. The term “cobalt” is derived from the German word “kobold,” meaning goblin. The element received this name because medieval miners looking for tin thought its ore released toxic vapors when smelted. The toxic vapors turned out to be arsenic, which was commonly found with cobalt.
- Cobalt is an essential component of all living organisms. It comprises the backbone of vitamin B12, which facilitates blood formation and nervous system functioning, among other important things.
3. Cobalt’s dominant current application is its function in lithium-ion batteries.
4. The element cobalt was the first metal to be discovered that was not an “ancient metal” like copper or gold. The scientist responsible, Georg Brandt, became the first recorded metal discoverer in history.
5. Cobalt compounds can create many pigments, not just cobalt blue. Cobalt phosphate can generate a violet color, and cobalt green results from combining cobalt oxides and zinc oxides.
6. The oldest cobalt-colored glass, discovered in Egypt, dates back to nearly 1550 BCE.
7. The cobalt isotope Co-60 is key to the production of gamma rays, which can be used to treat cancer and also sterilize medical supplies.
8. The European Union considers cobalt a “critical raw material” because few places exist in which cobalt can be mined in large quantities, and it also has extremely high demand.
9. In 2010, when German researchers captured the first-ever images of changing “spins” in an atom, they utilized cobalt. The term “spin” describes the angular momentum electrons exhibit as they travel around the nucleus.
10. Nearly a third of annually-produced cobalt funnels to the ceramic and paint industries.
Cobalt in the Periodic Table
Cobalt has atomic symbol Co, and atomic number 27. It is a silver-grey transition metal that lies to the right of iron, to the left of nickel, and above rhodium in the periodic table. It shares some physical and chemical properties with nickel. It’s an essential trace element in the body, and like iron it can be magnetized.
The electron configuration of the cobalt atom is [Ar]3d74s2 . Cobalt has an electronegativity of 1.88
Allotropes of Cobalt
Generally, the element cobalt exists as a mixture of two allotropes over a wide temperature range. The transformation between these states occurs at a very slow pace, which prompts variance in the observed physical properties of this element.
The beta form, or β-form, of cobalt assumes a closely-packed, hexagonal, crystalline structure. The alpha form, or α-form, exists as a cubic crystal. Although both allotropes are stable under normal conditions, the beta form dominates under temperatures of approximately 400°C, or 750°F. Conversely, the alpha form dominates above these temperatures until the element’s melting point, at 1490°C, or 2720°F.
Cobalt in the Environment
Researchers do not encounter cobalt as a free metal in the environment; they typically find it in the form of ores. The most common cobalt-sourcing ores include cobaltite, erythrite, skutterudite, and glaucodot. Miners tend to locate these ores in a variety of locations, including China, Russia, Australia, Finland, Azerbaijan, and the Democratic Republic of the Congo.
We can also access the element cobalt through other methods. This element can result as a by-product of the mining process for both copper and nickel. In the case of copper, any cobalt contained in this metal and smelted along with it gets oxidized. This oxidized metal, once treated by an electric furnace, gets reduced with carbon and forms a copper-iron-cobalt alloy. During nickel smelting, electrolytic refining facilitates the cobalt recovery process by precipitating it from the solution–typically in the form of cobaltic hydroxide. However, due to the decline in copper and nickel prices, mining facilities have struggled, prompting a net reduction in by-product cobalt production.
Cobalt can also enter the environment through the burning of coal and oil. Facilities in the electric power industry generate the largest amount of cobalt in this manner; when they burn fuels at their power plants, they release cobalt.
Additionally, production and utilization of cobalt-containing substances also results in an emission of cobalt to the environment. Products including, but not limited to, colored glass, paints, rubbers, cosmetics, pottery all contain cobalt compounds. These compounds likely include cobalt oxide, cobalt potassium nitrite, cobalt aluminate, and cobalt ammonium phosphate.
Most cobalt-containing compounds travel through the wind as dust. Cobalt can also enter surface water when runoff rainwater runs through soil and rock that have accumulated this metal.
As discussed, cobalt can also be found within animals–and within humans. In fact, cobalt is essential to all mammals in the form of cobalamin, or vitamin B12. This vitamin, a coordination complex of cobalt, fuels processes that ensure the health of blood and nerve cells. It also contributes to the DNA production process by serving as a cofactor during DNA synthesis.
History of the Element Cobalt
The term “cobalt” traces back to ancient Greek and medieval German cultures. According to the Latin novel Chronicles of Leoben, written in 1335, “kobolt” was associated with legends of gnomes living in the Schneeberg Mountain mines, located in Germany.
However, cobalt coloring processes have existed for nearly 3000 years. The element’s first artistic uses date back to cobalt-containing glazes on pottery and glass pieces; even some Ancient Egyptian tombs exhibit traces of cobalt. Chinese pottery from 600 CE also contains evidence of cobalt-containing blue dyes.
Discovery of Cobalt – who discovered it?
We credit Swedish scientist Georg Brandt with the official “discovery,” or chemical isolation, of the element cobalt. As a researcher and chemist, Brandt prided himself on his recognition of chemistry’s “flaws.” He sought to generate a more solid foundation of scientific knowledge relying solely on principles and axioms.
This pursuance of scientific facts fueled Brandt’s ultimate encounter with cobalt. Once he realized that the color of a blue pigment employed in glassmaking at the time had derived from an unknown metal, and he established this substance as an element and began studying it. In his 1735 novel Dissertatio de Semi-Metallis, Brandt cited his discovery of this new “semi-metal,” which he had named cobalt. Brandt’s claim was initially met with skepticism, because no new metals had ever been found.
Although we currently class cobalt as a transition metal, Brandt’s findings prompted a new wave of elemental research and expansion of the later-established periodic table. Also, interestingly, Brandt holds the title of the first person in history to ever discover a new metal.
Reactions, Compounds, Oxidation States, and Isolation
Cobalt + Air
This element does not react readily with air. However, upon heating, this combination results in the oxide Co3O4. And if the reaction transpires at a temperature exceeding 900°C, or BLANK°F, the combination generates CoO.
3Co(s) + 4O2(g) → 2Co3O4(s)
2Co(s) + O2(g) → 2CoO(s)
Cobalt + Halogens
Cobalt reacts with bromine to form cobalt(II) bromide: CoBr2.
Co(s) + Br2(l) → CoBr2(s) [green]
Cobalt reacts with chlorine and iodine in a similar manner.
Co(s) + Cl2(g) → CoCl2(s)
Co(s) + I2(s) → CoI2(s)
Cobalt dissolves in sulfuric acid to create products comprised of the Co(II) ion and hydrogen gas.
Co(s) + H2SO4(aq) → Co2+(aq) + SO42-(aq) + H2(g)
Cobalt + Water
Reflecting its behavior in the presence of air, cobalt does not react easily with water. However, CoO can result from the combination of hot cobalt metal and steam, as seen below.
2Co(s) + O2(g) → 2CoO(s)
Oxides & Hydroxides
Cobalt can generate two different binary compounds upon interaction with oxygen. These compounds include cobaltous oxide: CoO and tricobalt tetroxide: Co3O4. Cobalt exists in either the +2 or +3 oxidation states in tricobalt tetroxide. Additionally, nearly half of commercial cobalt oxide used in ceramics, glass, and enamel manufacturing is constituted by tricobalt tetroxide.
Cobalt (II) hydroxide, Co(OH)2, is insoluble in water, and when first precipitated is a beautiful blue color, that quickly turns pink Cobalt hydroxide, when added to hot, concentrated sodium hydroxide can form the blue-colored sodium cobaltate.
Cobalt Sulfates, Halides & Phosphates
The compound cobalt sulfate: CoSO4 holds key roles in processes such as electroplating, drying, and agricultural pasture top-dressing. This, along with other cobaltous salts, also lends itself to the production of catalysts, cobalt metal powders, and more salts.
Potassium cobaltinitrite: K₃[Co(NO₂)₆], also referred to as Indian Yellow, has a bright yellow, powdery appearance. It is predominantly used as a yellow pigment.
Cobaltous chloride: CoCl2 assumes a solid, pink form that transitions to blue as it dehydrates. This compound has uses as a catalyst and as an indicator of humidity.
Cobaltous phosphate: Co3(PO4)2∙8H2O is typically employed in painting and coloring processes involving surfaces such as porcelain and glass.
Meanwhile, cobalt ammonium phosphate: CoNH4PO4 generates a deep violet color. This compound also has applications in the artistic world.
Cobalt (II) & Cobalt (III) Coordination Complexes
Cobalt forms a variety of complexes with ligands such as ammonia, thiocyanate, phenanthroline, and the chloride ion. These ions can be blue or pink, usually corresponding to tetrahedral or octahedral complexes. Ethylenediamine forms a complex with cobalt (III). In fact, in many coordination complexes, cobalt is easily oxidized to the +3 state – especially when cobalt (II) chloride is mixed with ammonia. CoCl3X(NH3) is formed, with X being 4, 5 or 6, and each being a different color.
Cobalt Oxidation States
Cobalt tends to exhibit either a +2 or a +3 oxidation state when combining with other molecules to form compounds. The +2 oxidation state is the most common, and cobalt in the +3 oxidation state is usually unstable and a strong oxidizing agent. Still, oxidation states of +4, +1, 0, and −1 can also be observed.
“Cobaltous” compounds contain cobalt in its +2 oxidation state. Meanwhile, the term “cobaltic” denotes cobalt in its +3 oxidation state. This ion, Co3+, actually forms more known complex ions than any other metal except platinum.
Isolation of Cobalt
The element cobalt, as discussed, can typically be produced via reductive smelting. This process requires a variety of different metallic ores that occur in the environment. Cobalt can also result as a by-product of copper and nickel mining, processes which are described above. Cobalt is difficult to isolate in an amateur lab setting, but it can be done via electrolysis.
Cobalt’s Applications to Today’s World
What is Cobalt used for?
Cobalt has many uses in today’s world, including ties to commercial, industrial, medical, and military industries. The predominant, most utilitarian use of this element hinges on its role in rechargeable battery electrodes. Cobalt thus affects our daily lives; most devices from cell phones to laptops rely on it.
Gas turbine engines, key to the function of trains, planes, and boats, derive from superalloys; these superalloys require the presence of cobalt. Other products such as airbags, tires, drying agents, steels, magnetic recording media, magnets, tires, dyes and pigments, and even other alloys all involve the element cobalt.
In hospitals, the element cobalt plays a key role in the detector of tumors and cancerous metastases, equipment sterilization, and injury imaging. It can even be utilized in the creation of prosthetic alloys, which comprise different knee, joint, and dental replacements.
Cobalt’s obvious contributions to our world are compounded by its status as an essential metal. Many of these high-demand applications rely on cobalt, and cobalt alone; such specialist applications cannot be completed using substitutions from alternative metals. In 2011, its importance specifically to industrial and technological development prompted its recognition as “critical” in the European Union and “strategically important” in the United States.
But high enough concentrations of cobalt may produce unpleasant effects. Cobalt poisoning may result from swallowing the metal, breathing it in, or its prolonged contact with the skin. Elevated blood cobalt concentrations prompt endocrine, hematological, cardiovascular, and even neurological issues in both animals and humans.
Organizations such as the Cobalt Institute study the effects of environmental cobalt exposure levels on both aquatic and land-dwelling organisms. These developed concentrations can be deemed “safe,” thus informing the companies and industries that use the element.
Physical Properties of Cobalt
- Symbol: Co
- Melting point: 1,768 K; 1,495°C; 2,723°F
- Boiling point: 3,143 K; 2,870°C; 5,198 °F
- Density: 8.86 g/cm^3
- Atomic weight: 58.93
- Atomic number: 27
- Electronegativity: 1.88
- Classification: metal
- Natural abundance of 0.003% in the earth’s crust
- Electron shell configuration: [Ar] 3d7 4s2
- Isotopes: the most abundant isotopes of cobalt include 56-Co, 57-Co, 58-Co and 60-Co
- The only stable, naturally-occurring isotope of cobalt is 59-Co
- Found: most cobalt comes from different ores obtained from mines and natural deposits
- Cobalt is ferromagnetic
Toxicity: cobalt is non-toxic, but excessive exposure has proven dangerous
Where Can I Buy the Element Cobalt?
You can purchase cobalt metal in powder form or pieces of metal from many different vendors, including Amazon, eBay and specialty stores. Products containing cobalt, such as those covered in this article, are also widely available across the internet.