Units of amount of substance

The unit of amount of substance in the International System of Units (SI) is the mole (symbol: mol). The mole is defined as the quantity of substance that contains as many elementary entities (such as atoms, molecules, ions, etc.) as there are in 12 grams of carbon-12 (^12C). This number, known as Avogadro's number, is approximately \(6.022 \times 10^{23}\) entities per mole.