Cobalt

Cobalt, ₂₇Co
Cobalt
Pronunciation	/ˈkoʊbɒlt/
Appearance	Hard lustrous bluish gray metal
Standard atomic weight Ar°(Co)
	58.933194±0.000003; 58.933±0.001 (abridged);
Cobalt in the periodic table
	iron ← cobalt → nickel
Atomic number (Z)	27
Group	group 9
Period	period 4
Block	d-block
Electron configuration	[Ar] 3d7 4s2
Electrons per shell	2, 8, 15, 2
Physical properties
Phase at STP	solid
Melting point	1768 K (1495 °C, 2723 °F)
Boiling point	3200 K (2927 °C, 5301 °F)
Density (at 20° C)	8.834 g/cm3
when liquid (at m.p.)	7.75 g/cm3
Heat of fusion	16.06 kJ/mol
Heat of vaporization	377 kJ/mol
Molar heat capacity	24.81 J/(mol·K)
Atomic properties
Oxidation states	common: +2, +3; −3, −1, 0, +1, +4, +5
Electronegativity	Pauling scale: 1.88
Ionization energies	1st: 760.4 kJ/mol ; 2nd: 1648 kJ/mol ; 3rd: 3232 kJ/mol ; (more) ;
Atomic radius	empirical: 125 pm
Covalent radius	Low spin: 126±3 pm; High spin: 150±7 pm
	Spectral lines of cobalt
Other properties
Natural occurrence	primordial
Crystal structure	hexagonal close-packed (hcp) (hP2)
Lattice constants	a = 250.71 pm; c = 407.00 pm (at 20 °C)
Thermal expansion	12.9×10−6/K (at 20 °C)
Thermal conductivity	100 W/(m⋅K)
Electrical resistivity	62.4 nΩ⋅m (at 20 °C)
Magnetic ordering	Ferromagnetic
Young's modulus	209 GPa
Shear modulus	75 GPa
Bulk modulus	180 GPa
Speed of sound thin rod	4720 m/s (at 20 °C)
Poisson ratio	0.31
Mohs hardness	5.0
Vickers hardness	1043 MPa
Brinell hardness	470–3000 MPa
CAS Number	7440-48-4
History
Discovery and first isolation	Georg Brandt (1735)
Isotopes of cobalt v; e;
	Category: Cobalt; view; talk; edit; \| references

Cobalt is a chemical element; it has symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a 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, somewhat brittle, gray metal.

Cobalt-based blue pigments (cobalt blue) have been used since antiquity for jewelry and paints, and to impart a distinctive blue tint to glass. The color was long thought to be due to the 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 off poisonous arsenic-containing fumes when smelted.^[9] In 1735, such ores were found to be reducible to a new metal (the first discovered since ancient times), which was ultimately named for the kobold.

Today, some cobalt is produced specifically from one of a number of metallic-lustered ores, such as cobaltite (CoAsS). The element is more usually produced as a by-product of copper and nickel mining. The Copperbelt in the Democratic Republic of the Congo (DRC) and Zambia yields most of the global cobalt production. World production in 2016 was 116,000 tonnes (114,000 long tons; 128,000 short tons) (according to Natural Resources Canada), and the DRC alone accounted for more than 50%.^[10]

Cobalt is primarily used in lithium-ion batteries, and 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 also used in the petroleum industry as a catalyst when refining crude oil. This is to purge it of sulfur, which is very polluting when burned and causes acid rain.^[11]

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.

The name cobalt derives from a type of ore considered a nuisance by 16th century German silver miners, which in turn may have been named from a spirit or goblin held superstitiously responsible for it; this spirit is considered equitable to the kobold (a household spirit) by some, or, categorized as a gnome (mine spirit) by others.

^ "cobalt". Oxford English Dictionary (2nd ed.). Oxford University Press. 1989.
^ "Standard Atomic Weights: Cobalt". CIAAW. 2017.
^ Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (May 4, 2022). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
^ ^a ^b Arblaster, John W. (2018). Selected Values of the Crystallographic Properties of Elements. Materials Park, Ohio: ASM International. ISBN 978-1-62708-155-9.
^ Co(–3) is known in Na₃Co(CO)₃; see John E. Ellis (2006). "Adventures with Substances Containing Metals in Negative Oxidation States". Inorganic Chemistry. 45 (8). doi:10.1021/ic052110i.
^ ^a ^b ^c ^d Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 28. ISBN 978-0-08-037941-8.
^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. pp. 1117–1119. ISBN 978-0-08-037941-8.
^ Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
^ "cobalt". Oxford English Dictionary (2nd ed.). Oxford University Press. 1989.
^ Danielle Bochove (November 1, 2017). "Electric car future spurs Cobalt rush: Swelling demand for product breathes new life into small Ontario town". Vancouver Sun. Bloomberg. Archived from the original on July 28, 2019.
^ "Catalysts". Cobalt Institute. Archived from the original on August 16, 2023. Retrieved August 15, 2023.

Cite error: There are <ref group=lower-alpha> tags or {{efn}} templates on this page, but the references will not show without a {{reflist|group=lower-alpha}} template or {{notelist}} template (see the help page).

[1] "cobalt". Oxford English Dictionary (2nd ed.). Oxford University Press. 1989.

[2] "Standard Atomic Weights: Cobalt". CIAAW. 2017.

[CIAAW2021-3] Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (May 4, 2022). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.

[Arblaster_2018-4] Arblaster, John W. (2018). Selected Values of the Crystallographic Properties of Elements. Materials Park, Ohio: ASM International. ISBN 978-1-62708-155-9.

[5] Co(–3) is known in Na₃Co(CO)₃; see John E. Ellis (2006). "Adventures with Substances Containing Metals in Negative Oxidation States". Inorganic Chemistry. 45 (8). doi:10.1021/ic052110i.

[GE28-6] Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 28. ISBN 978-0-08-037941-8.

[greenwood-7] Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. pp. 1117–1119. ISBN 978-0-08-037941-8.

[NUBASE2020-9] Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.

[10] "cobalt". Oxford English Dictionary (2nd ed.). Oxford University Press. 1989.

[Bochove-11] Danielle Bochove (November 1, 2017). "Electric car future spurs Cobalt rush: Swelling demand for product breathes new life into small Ontario town". Vancouver Sun. Bloomberg. Archived from the original on July 28, 2019.

[12] "Catalysts". Cobalt Institute. Archived from the original on August 16, 2023. Retrieved August 15, 2023.

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