Chemical reactions occur on an atomic scale. We cannot physically count individual reacting particles. The mole concept is the essential tool that connects the microscopic world of atoms to the macroscopic world of laboratory measurements.
The Mole & Avogadro Constant (NA)
The mole (mol) is the SI unit of amount of substance. One mole contains exactly 6.02 × 10²³ elementary entities (atoms, molecules, ions, or electrons). This number is the fixed numerical value of the Avogadro constant, NA.
Molar Mass (M)
Molar mass is the mass of exactly one mole of a given substance, in units of g mol⁻¹. It is numerically equivalent to the relative atomic mass (\(A_r\)) for elements, or the relative formula mass (\(M_r\)) for compounds.
Mole Calculations (n = m / M)
\[ n = \frac{m}{M} \]
Converting Between Mass, Moles, and Number of Particles
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