N = n × Nₐ (6.022 × 10²³)
To convert moles to individual particles, multiply by Avogadro's number: N = n × 6.022 × 10²³. For molecules with multiple atoms, the total atom count = molecules × atoms per molecule. Example: 2.5 mol H₂O = 2.5 × 6.022 × 10²³ = 1.506 × 10²⁴ molecules. Since each H₂O has 3 atoms (2H + 1O), total atoms = 4.517 × 10²⁴. The reverse conversion (atoms to moles) divides by Nₐ. These conversions are essential for understanding reaction stoichiometry at the particle level, nuclear chemistry (counting individual decays), and nanotechnology (counting atoms in nanostructures). In one breath, you inhale roughly 2.5 × 10²² molecules of air.