Amount of substance

Ratio of the number of particles in a sample to Avogadro's constant

In chemistry, the amount of substance (symbol n) in a given sample of matter is defined as a ratio (n = N/NA) between the number of elementary entities (N) and the Avogadro constant (NA). It is one of the seven base quantities of the International System of Units, SI. The unit of amount of substance in the SI is the mole (symbol: mol), a base unit. Since 2019, the mole has been defined such that the value of the Avogadro constant NA is exactly 6.02214076×1023 mol−1, defining a macroscopic unit convenient for use in laboratory-scale chemistry.

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