Avogadro’s number is the fixed number of particles (atoms, molecules, or ions) present in one mole of a substance.
It is equal to: 6.022 × 10²³
This means:
- 1 mole of atoms contains 6.022 × 10²³ atoms.
- 1 mole of molecules contains 6.022 × 10²³ molecules.
- 1 mole of ions contains 6.022 × 10²³ ions.
Example:
- 1 mole of oxygen gas (O₂) has 6.022 × 10²³ O₂ molecules.
- 1 mole of sodium chloride (NaCl) has 6.022 × 10²³ formula units of NaCl.
Avogadro’s number is named after the Italian scientist Amedeo Avogadro, who proposed that equal volumes of gases at the same temperature and pressure contain the same number of particles.