* Avogadro's Number: One mole of any substance contains 6.022 x 10^23 particles (atoms, molecules, etc.). This is known as Avogadro's number.

* Chlorine Atoms: The chemical symbol "Cl" represents a single chlorine atom.

Calculation:

Since 1 mole of Cl contains 6.022 x 10^23 chlorine atoms, there are 6.022 x 10^23 chlorine atoms in 1.00 mole of Cl.