Avogadro constant

fundamental physical constant (symbols: L, Nᴀ) representing the molar number of entities

The Avogadro constant (symbols: L, NA) is the number of particles (usually atoms or molecules) in one mole of a given substance.[2] Its value is equal to 6.02214129(27)×1023 mol−1.[3] The constant was named after the Italian scientist Amedeo Avogadro.

Value of NA[1] in various units
6.02214179(30)×1023 mol−1
2.73159757(14)×1026 lb-mol−1
1.707248479(85)×1025 oz-mol−1

The measurement of Avogadro's constant was refined in 2011 to 6.02214078×1023 ± 0.00000018×1023.[4]

An old term closely related to the Avogadro constant is Avogadro's number. Avogadro's number is the number of atoms in 12 grams of the carbon isotope carbon-12. Avogadro's number is a dimensionless quantity and has the numerical value of the Avogadro constant given in base units.



  1. Mohr, Peter J.; Taylor, Barry N.; Newell, David B. (2008). "CODATA Recommended Values of the Fundamental Physical Constants: 2006" (PDF). Rev. Mod. Phys. 80: 633–730. Bibcode:2008RvMP...80..633M. doi:10.1103/RevModPhys.80.633. Direct link to value.
  2. Johnston, Lesley (2008). Salters Advanced Chemistry: Revise Chemistry For Salters AS (Second ed.). Heinemann. p. 2. ISBN 978-0-435-63154-3.
  3. "Avogadro constant". National Institute of Standards and Technology. Retrieved 2013-11-07.
  4. Andreas, Birk; et al. (2011). "Determination of the Avogadro Constant by counting the atoms in a 28Si Crystal". Physical Review Letters. 106 (3): 030801. arXiv:1010.2317. Bibcode:2011PhRvL.106c0801A. doi:10.1103/PhysRevLett.106.030801. PMID 21405263. S2CID 18291648.