Avogadro's number, which is approximately 6.022 × 10^23, represents the number of particles (atoms, molecules, ions, etc.) in one mole of a substance. This value is derived from experimental observations and is a fundamental constant in chemistry.
In the case of iron (Fe), one mole of iron contains Avogadro's number (6.022 × 10^23) of iron atoms. So, there are approximately 6.022 × 10^23 atoms in a mole of iron.