Basis for Particle Size-Selective Sampling for Beryllium

Beryllium (Be) is a light alkaline earth metallic element of atomic number 4 having one natural isotope with atomic mass number 9 associated with five neutrons (atomic weight: 9.0122). A silver-white metal of low density (1.85 g/cm³), beryllium is the lightest of the structural metals. It has the following natural properties: melting point, 1283°C; boiling point, 2970°C; covalent radius, 0.9 angstroms; ionic radius, 0.31 angstroms; oxidation number, 2; hexagonal crystal structure; and ionization energies, 9.32 ev and 18.21 ev. The principal sources of beryllium are the natural silicate ores: beryl, bertrandite, and phenacite; the most important is the mineral beryl, Be₂A_l2(SiO₃)₆. The white, crystalline beryllium oxide is obtained by combustion of beryllium or its compounds in air. It resembles aluminum oxide in being refractory (m.p. 2570°C) and in having polymorphs. The high temperature forms (> 800°C) are exceedingly inert and insoluble. Because of the beryllium atom's small size (ionic radius 0.34 angstroms) and high ionization potential (9.32 ev), its lattice and hydration energies are not sufficient to result in complete charge separation to form Be²⁺ ions, and all beryllium compounds exhibit covalent bonding of Be. Samples containing beryllium can be 40accurately assayed by dissolution and atomic absorption spectroscopy measurement to 0.01 mg/L. ¹ - ³