The mole, symbol mol, is the SI unit of @A00297@. One mole contains exactly \(6.022\ 140\ 76 \times 10^{23}\) elementary entities. This number is the fixed numerical value of the @A00543@, \(N_{\text{A}}\), when expressed in the unit \(\text{mol}^{\text{-1}}\) and is called the Avogadro number.
The @A00297@, 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.
The formulation of this definition was agreed upon by the 26th CGPM in November 2018 with effect from 20 May 2019.
BIPM, The International System of Units, SI Brochure, 9th ed. (2019), p. 134 [Terms] [Book]