* Chlorine-35 (³⁵Cl): This isotope has an atomic mass of approximately 34.9689 amu (atomic mass units). It accounts for about 75.77% of naturally occurring chlorine.

* Chlorine-37 (³⁷Cl): This isotope has an atomic mass of approximately 36.9659 amu. It makes up about 24.23% of naturally occurring chlorine.

The average atomic mass of chlorine, which is the weighted average of the atomic masses of its isotopes, is 35.453 amu. This is the value you will typically find on the periodic table.