Here's a breakdown:
* Isotopes: Atoms of the same element (like chlorine) that have the same number of protons but different numbers of neutrons. This difference in neutrons leads to different atomic masses.
* Chlorine Isotopes: There are two main isotopes of chlorine:
* Chlorine-35 (³⁵Cl): This isotope has 17 protons and 18 neutrons.
* Chlorine-37 (³⁷Cl): This isotope has 17 protons and 20 neutrons.
* Molecular Mass: A chlorine molecule (Cl₂) is formed by two chlorine atoms bonding together. The mass number of the molecule will depend on the combination of isotopes present.
Here are the possible combinations and their mass numbers:
1. ³⁵Cl - ³⁵Cl: The mass number is 35 + 35 = 70
2. ³⁵Cl - ³⁷Cl: The mass number is 35 + 37 = 72
3. ³⁷Cl - ³⁷Cl: The mass number is 37 + 37 = 74
Therefore, chlorine molecules can have three different values of mass number (70, 72, and 74) due to the presence of two chlorine isotopes and their various combinations in the molecule.
