Amount of substance

Amount of substance
Approximately 1 mol amount of substance based on 12 grams of carbon-12
Common symbols	n
SI unit	mol
Dimension	${\displaystyle {\mathsf {N}}}$

In chemistry, the amount of substance (symbol n) in a given sample of matter is defined as a ratio (n = N/N_A) between the number of elementary entities (N) and the Avogadro constant (N_A). The entities are usually molecules, atoms, or ions of a specified kind. The particular substance sampled may be specified using a subscript, e.g., the amount of sodium chloride (NaCl) would be denoted as n_NaCl. The unit of amount of substance in the International System of Units is the mole (symbol: mol), a base unit.^[1] Since 2019, the value of the Avogadro constant N_A is defined to be exactly 6.02214076×10²³ mol⁻¹. Sometimes, the amount of substance is referred to as the chemical amount or, informally, as the "number of moles" in a given sample of matter.