| Definition: | SI unit of amount of substance, equal to the amount of substance of a system that contains 6,022 140 76 × 1023 specified elementary entities
Note 1 to entry: The definition in the SI Brochure is: "The mole, symbol mol, is the SI unit of amount of substance. One mole contains exactly 6,022 140 76 × 1023 elementary entities. This number is the fixed numerical value of the Avogadro constant, NA, when expressed in the unit mol−1 and is called the Avogadro number.
The amount of substance, symbol n, of a system is a measure of the number of specified elementary entities. An elementary entity may be an atom, a molecule, an ion, an electron, any other particle or specified group of particles."
Note 2 to entry: The definition of the mole in IEV 112-02-09:2010-01 fixed the value of the molar mass of carbon 12, M(12C), as exactly equal to 0,012 kg/mol. According to the current definition of the mole, M(12C) is no longer known precisely and has to be determined experimentally.
Note 3 to entry: The mole is one of the seven SI base units: second (s), metre (m), kilogram (kg), ampere (A), kelvin (K), mole (mol) and candela (cd).
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