Particle number

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The number of particles ( symbol :) is an extensive physical quantity of the dimension number and describes the absolute number of particles in a system . The number of particles has the unit one and is directly proportional to the amount of substance . If the information relates only to a certain substance X of a mixture , its name or chemical formula is added as an index to the symbol for the number of particles and thus obtained .

Particle numbers can no longer be determined directly for macroscopic systems. Therefore, for the sake of simplicity, the amount of substance is given in its unit of mole instead . The number of particles in one mole is also called Avogadro's constant , which has had the following exact value since the redefinition of the International System of Units in 2019 :

and with their help you can convert the number of particles and the amount of substance into each other:

Individual evidence

  1. DIN EN ISO 80000-1: 2013, sizes and units - general , chap. 3.8 and 5.
  2. DIN EN ISO 80000-11: 2013, sizes and units - parameters of the dimension number , chap. 0.3.
  3. CODATA Recommended Values. National Institute of Standards and Technology, accessed July 30, 2019 . Value for the Avogadro constant. The value is exact.