Alkaline Earth Metals
Beryllium (Be), the smallest alkaline earth metal, is atomic number 4 on the periodic table, has an atomic weight of 9.01 amu (atomic mass unit), and melting and boiling points of 2,348.6°F (1,287°C) and about 4,479.8°F (2,471°C), respectively. It was discovered by N. L. Vauquelin in 1797 after a mineralogist named R. J. Hauy noticed that emeralds and beryl possessed many similar properties and might be identical substances, but it was not until 30 years later that the free metal was isolated (independently) by F. Wohler and A. Bussy. It occurs naturally in the precious stones emerald and aquamarine, which are both forms of the mineral beryl, a beryllium aluminosilicate compound.
Beryllium has no biochemical function and is extremely toxic to human beings, but small amounts (about 2%) impart superior characteristics, such as high strength, wear resistance, and temperature stability, to alloys. Copper-beryllium alloys make good hand tools in industries that use flammable solvents, because the tools do not cause sparks when struck against other objects. Nickel-beryllium alloys are used for specialized electrical connections and various high temperature applications. Beryllium is used instead of glass in x-ray tubes because it lets through more of the x-ray radiation than glass would.