Definition:Avogadro's Number
Definition
Avogadro's number is defined as the number of particles in a mole.
Its value is defined as:
- $6 \cdotp 02214 076 \times 10^{23}$
Thus it is the constant of proportion for converting the mass of one mole of a substance to the (arithmetic) mean mass of one molecule of that substance.
Symbol
- $N_{\mathrm 0}$
A symbol often used for Avogadro's number is $N_{\mathrm 0}$.
Its $\LaTeX$ code is N_{\mathrm 0} .
Also see
Source of Name
This entry was named for Lorenzo Romano Amedeo Carlo Avogadro.
Historical Note
The name Avogadro's number was coined in $1909$ by Jean Baptiste Perrin, who defined it as the number of molecules in exactly $16$ grams of oxygen.
In $1971$, Avogadro's number was redefined as the number of atoms in $0.012$ kilograms of carbon-$12$.
It was further redefined in $2019$ to have the fixed number $6.02214076 \times 10^{23}$, and to base the mole on that.
Sources
- 1978: A.P. French and Edwin F. Taylor: An Introduction to Quantum Physics ... (previous) ... (next): $1$: Simple models of the atom: $\text {1-3}$: The Electrical Structure of Matter