History and Production
From Greek word beryllos, meaning "beryl". Beryllium was discovered as the oxide by L.-N. Vauquelinin in beryl and in emaralds in 1798. The metal was isolated in 1828 by F. Woehler and independantly by A.A.B. Bussy by the reaction of potassium on beryllium chloride. Beryllium can be extracted by roasting beryl with Na2SiF6 at 700°C.
It is, however, more commonly produced by reduction of beryllium fluoride with magnesium at 1300°C. The metal is used as an alloying agent and as a structural material for aircraft, spacecraft and satellites. For example, about 2% of Be will increase the strength of copper by sixfold. The alloy is used for springs and electrical connections.
Beryllium is also used in nuclear reactors as a moderator due to its low thermal neutron adsorption cross section.
It is nonmagnetic and steel grey in color and has one of the highest melting points of the light metals. Its elasticity modulus is about a third greater than that of steel and with good thermal conductivity. Beryllium and its salts are toxic although they are sweetish in nature. Attempt must NOT be made to taste Be or its compounds!
Interatomic distance: 222.6 pm
Melting point: 1287°C
Boiling point: 2471°C
Thermal conductivity/Wm-1K-1: 200 (27°C)
Density/kgm-3: 1847.7 (20°C), 1690 (m.p.)
Standard Thermodynamic Data (atomic gas)
Enthalpy of formation: 324 kJ/mol
Gibbs free energy of formation: 286.6 kJ/mol
Entropy: 136.3 J/mol K
Heat capacity: 20.8 J/mol K
Electronic configuration: [He] 2s2
Term symbol: 1S0
Electron affinity: (not stable) Electronegativity (Pauline): 1.57
Ionization energy (first, second, third): 899.4, 1757.1, 14848 kJ/mol
The metal is relatively unreactive compared with the other alkaline earth metals, due to its small size and the valence electrons are more tightly bound to the atom. Beryllium does not react with water and does not oxidized in air below 600°C.
However, finely divided metal burns brilliantly in the atmosphere to give BeO and Be3N2.