Cobalt Element

Cobalt Element Facts

Cobalt (Co) is an element that has the atomic number 27. The free element is hard, lustrous, silver-gray metal and is produced reductive smelting. It is found naturally only in a chemically combined form. The term cobalt originated from the German word “kobold” that means elf or goblin.

Cobalt is one of the most common elements in the period table as it is normally found in association with silver, nickel, lead, iron and copper. It is primarily a hard, silvery white metal that is available in nature as cobalt-59. It is also a part of the minerals erythrite, smaltite, cobaltite, and other ores; and has similar physical properties to nickel and iron.

Cobalt Element Uses

Cobalt has little ductility and relatively low strength at normal temperatures, and is one of the different components of numerous alloys. It has been used to produce ceramics and blue glass since ancient times.

In 1735, George Brandt first isolated the element and showed that the main cause of the blue color in glass is a consequence of the presence of the cobalt element and not bismuth as what was previously thought. It is present in various ores as isotopes 59, but when produced by neutron activation components in nuclear reactors, cobalt-60 is formed and can also be produced in a particle accelerator.

It is used as component of numerous alloys that include stellite and carboloy, which are used in making very hard cutting tools. The alloy Alnico, composed of cobalt, nickel, aluminum, and other metals is used in making high strength and permanent magnets. Cobalt is also used in the production of some stainless steels, and in the electroplating process to provide hard surfaces that are resistant to oxidation.

The high energy gamma rays that are being emitted during the radioactive decay of cobalt-60 is sometimes used in detecting flaws in the components of metals and in treating various types of cancer in the process of brachytherapy  — a method of radiation treatment wherein sealed sources are being used in delivering radiation doses at distances that are up to a few centimeters by surface, interstitial, or intracavitary application.

Cobalt Isotopes

Cobalt has 26 isotopes that have been identified. Cobalt-48, cobalt-49 and cobalt-51 are all non-radioactive while the other isotopes that have been synthesized are. Cobalt-59 is stable and occurs naturally. It has a magnetic permeability that is approximately 2/3 of iron. The boiling point of cobalt is 5198 degree Fahrenheit, melting point of 2723 degree Fahrenheit and specific gravity of 8.9 (68 degree Fahrenheit). Its valence is positive 2 or 3 and a mixture of two allotropes over a wide temperature range.

 Cobalt Element References and Further Reading

Tamuk; Argonne; Pomoda College Department of Chemistry; University of Minnesota Biocatalysis Database.