(Avogadro's number) - the number of structural elements (atoms, molecules, ions or other particles) in 1 mole. It is named in honour of A. Avogadro and is denoted NA. The Avogadro constant is one of the fundamental physical constants, and it is essential for determining many others (the Boltzmann constant, the Faraday constant and others). One of the best experimental methods of determining the Avogadro constant rests on measuring the electric charge needed to decompose a known number of moles of a compound substance electrolytically and on measuring the charge of the electron. The most reliable value of the Avogadro constant (as of 1984) is NA = 6.022045(31)*1023 mol-1.