Avogadro constant

The Avogadro constant (symbol: L or N_A) is a physical constant that relates measurements made at the macroscopic scale to those made on an atomic scale. It is usually defined as the number of entities (such as atoms or molecules) in one mole, and the 2006 CODATA recommended value is 6.022 141 79(30) × 10²³ mol⁻¹. It was orginally called Avogadro's number, and is named in honour of the Italian physicist Amadeo Avogadro.

Proposed redefinition

In the context of the "New SI", based around the redefinition of the kilogram in terms of a universal physical constant, there have been several proposals that would give the Avogadro constant a defined value in SI units.