One mole always contains 6.022 × 10²³ particles.
This fixed value is known as Avogadro’s number. The particles can be:
- Atoms → in the case of elements like carbon or helium.
- Molecules → in the case of compounds like H₂O or O₂.
- Ions → in ionic compounds like Na⁺ or Cl⁻ in NaCl.
Examples:
- 1 mole of hydrogen atoms (H) = 6.022 × 10²³ atoms.
- 1 mole of water molecules (H₂O) = 6.022 × 10²³ molecules.
- 1 mole of sodium ions (Na⁺) = 6.022 × 10²³ ions.
So no matter what the substance is, one mole always represents the same number of particles.