Alkaline Earth Metals
Barium (Ba) is atomic number 56, has an atomic weight of 137.27 amu, and has melting and boiling points of 1,340.6°F (727°C) and about 3,446.6°F (1,897°C), respectively. It was isolated in 1808 by Davy, using a variation of his usual electrolytic process. Barite (the sulfate) is the main ore from which barium can be obtained, although witherite (the carbonate) was at one time also mined. It is not particularly plentiful, occurring in about 500 parts per million in the earth's crust, and on the average about 10 parts per billion in seawater. By far, most of the barium sulfate mined is used to make a sort of lubricating mud used in well-drilling operations, although small amounts of barium are alloyed with nickel for specialized uses, and some barium is used in medicine. Barium itself is toxic and has no biochemical function in living things.