Cobalt it reacts slowly with mineral acids, and very slowly with moist, but not with dry, air. Common oxidation states of cobalt include +2 and +3, although compounds with oxidation states ranging from −3 to +5 are also known. A common oxidation state for simple compounds is +2 (cobalt(II)). These salts form the pink-colored metal aquo complex [Co(HO)] in water. Addition of chloride gives the intensely blue . In a borax bead flame test, cobalt shows deep blue in both oxidizing and reducing flames. Several oxides of cobalt are known. Green cobalt(II) oxide (CoO) has rocksalt structure. It is readily oxidized
Cobalt (Co). The primary decay mode for isotopes with atomic mass unit values less than that of the most abundant stable isotope, Co, is electron capture and the primary mode of decay in isotopes with atomic mass greater than 59 atomic mass units is beta decay. The primary decay products below Co are element 26 (iron) isotopes; above that the decay products are element 28 (nickel) isotopes. Cobalt compounds have been used for centuries to impart a rich blue color to glass, glazes, and ceramics. Cobalt has been detected in Egyptian sculpture, Persian jewelry from the third millennium BC, in the