Cobalt is a transition metal. It is shiny and conducts electricity. It is magnetic. It is a hard metal. It is moderately reactive. Iron is more reactive and copper is less reactive. It dissolves slowly in acids. This reaction makes hydrogen and a salt of cobalt. Cobalt is normally in its +2 oxidation state as an ion. Some chemical compounds contain cobalt ions in its +4 oxidation state. Cobalt(II) chloride is one of the most common cobalt compounds. Many cobalt compounds are blue or pink. One of them is black.
Occurrence and preparation [change]
Cobalt is too reactive to occur pure in the earth. It is found in certain minerals. It is found with copper and nickel deposits. Normally the three metals are bonded to arsenic and sulfur. It is found as a byproduct (left over substance) when copper and nickel are produced. It is made by reaction with the sludge from copper and nickel processing.
Cobalt is used in some types of steel. It hardens the steel. It is also used to make very strong tough alloys. These alloys are known as superalloys. Some cobalt compounds are used in the lithium-ion battery. Cobalt compounds were used as an artificial food coloring until 1971. It was discovered that it has harmful effects. It is used to make glass blue. It is also used as a catalyst. It is also used in some medicines.
Cobalt compounds are needed in small amounts, but they are toxic in large quantities. Sometimes cobalt compounds were added to beer and poisoned people that drank it. It can make skin irritation when touched.