Avogadro number

Avogadro's Number is a fundamental constant of chemistry and physics, named after the Italian scientist Amedeo Avogadro. It defines the number of particles (such as atoms, molecules, ions or electrons) in one mole of a substance.

Definition

Avogadro's Number, often represented by the symbol N_A, is defined as exactly 6.02214076×10²³ entities per mole. This value was adopted by the International Committee for Weights and Measures in 2018.

History

The concept of Avogadro's Number was first introduced by Jean Baptiste Perrin in the early 20th century. However, it was named after Amedeo Avogadro, who, in 1811, hypothesized that equal volumes of gases at the same temperature and pressure contain the same number of molecules, a principle now known as Avogadro's law.

Applications

Avogadro's Number is used in stoichiometric calculations in chemistry. It allows chemists to calculate the amount of reactants needed or products formed in a chemical reaction. It is also used in physics to calculate the number of atoms or molecules in a given volume of gas, using the ideal gas law.

See also

• Mole (unit)
• Stoichiometry
• Ideal gas law
• Amedeo Avogadro