Compounds:

• CoF₂: cobalt (II) fluoride
• CoF₃: cobalt (III) fluoride
• CoF₄: cobalt (IV) fluoride
• CoCl₂: cobalt (II) chloride
• CoCl₂.6H₂O: cobalt (II) chloride 6-water
• CoCl₃: cobalt (III) chloride
• CoBr₂: cobalt (II) bromide
• CoI₂: cobalt (II) iodide
• CoO: cobalt (II) oxide
• Co₃O₄: cobalt (II, III) oxide
• CoS: cobalt (II) sulphide
• CoS₂: cobalt (II) sulphide
• Co₂S₃: cobalt (III) sulphide
• CoTe: cobalt (II) telluride

Uses of Cobalt:

     Cobalt is used in electroplating. Electroplating is the process in which something is coated by a thin metal through electrolysis. Cobalt gives objects a surface that is very attractive and resists oxidation. However, its commonly used to form alloys, a mixture or solid made up of two or more metals. One example would be alnico, an alloy that not only contains cobalt but aluminum and nickel, used to make powerful magnets. Cobalt is also used in alloys that make things such as gas turbines, jet engines, magnetic steels and some stainless steels. Cobalt catalysts are also used in the chemical industry for various methods. Finally, cobalt is also combined with chromium and tungsten, to create a stellite alloy, which is used to create high speed and temperature cutting tools and dyes. One isotope Cobalt-60 is radioactive and is a source of gamma rays and is used to help treat some forms of cancer. The half life of this element is 5.27 years and through beta decays becomes nickel-60. Having such a beautiful color, cobalt compounds have also been used to dye porcelain, glass, pottery, tile and enamel. Prosthetic devices, such as fake knees and hips are also made from the high-strength and corrosion-resistant alloys that are based on iron, cobalt or titanium. Cobalt compounds are also used in paint pigments. Cobalt acts as a binder for tungsten carbide in manufacturing drill bits and machine tools. Cobalt is also added to soil, plants, and to livestock feed that is lacking in cobalt to prevent serious wasting diseases in cattle and sheep. Examples of cobalt deprivation in animals are anemia, decreased lactation, retarded growth and a loss of appetite. Cobalt is essential to part of vitamin B₁₂, and is therefore an important part of human nutrition. Cobalt is the heart of the B12 vitamin, which when deficient can cause pernicious anemia. This is when one's body cannot produce enough red blood cells to transport all the oxygen that the body needs. This vitamin can also help maintain the nerve tissue and it is needed for the ability to release carbohydrates and fats. Cobalt is also needed by blue-green algae and the other nitrogen-fixing organisms. Cobalt steel (and its highly magnetic properties) was patented in Japan in 1917 and it was used in the beginning of War War II by Nazi Germany in magnetic mines. Cobalt was also used for making "sympathetic" or " invisible ink". The ink remains unseen until it is warmed. Although it's unsure who first discovered the ink, it is known to have been used to send secret messages in the seventeenth century.  Jean Hellot revealed the existence of the ink around 1700, but it was still used in espionage. Another trick that became popular in the nineteenth century was using artificial flowers that could respond to weather changes. The petals were dyed pink with a solution of cobalt chloride, and when the weather was wet or humid they would remain pink. However, if the weather became sunny and dry, they would turn violet and sometimes blue. Finally, the metal powder of cobalt is a fire hazard. Also the compounds of cobalt should be considered toxic and some carcinogenic.