Avogadro's Number
The exact number of elementary entities (atoms, molecules, ions) contained in one mole of a substance.
Governing formula
Na = 6.02214076 × 10²³ mol⁻¹
SI unit
mol⁻¹
In depth
Avogadro's constant connects macroscopic chemical mass (grams) to microscopic atomic mass (atomic mass units). It enables quantitative stoichiometry in thermodynamics and chemistry.
Examples in the real world
One mole of pure carbon-12 has a mass of exactly 12 grams and contains 6.022 × 10²³ carbon atoms.