Avogadro's Number
The number of elementary entities in one mole of substance, fixed by definition at 6.02214076 × 10²³ mol⁻¹.
Formula / equation
N = n × N_A
Unit
mol⁻¹
In depth
Named after Amedeo Avogadro, whose hypothesis linked gas volume to particle number, the constant scales the atomic mass unit up to the gram. Its magnitude is what makes atoms invisible yet chemistry weighable: a teaspoon of water holds more molecules than there are stars in the observable universe.
Examples in the real world
Counting 6.022 × 10²³ carbon atoms gives exactly 12.011 g of natural carbon; the same count of electrons carries one faraday of charge, 96,485 C.