Cl₂(g) represents chlorine gas, which consists of two chlorine atoms bonded together.
Chloride ion (Cl⁻): The negatively charged ion formed when chlorine gains one electron.
Monoatomic molecule: A molecule consisting of only one kind of atom bonded together (e.g., Cl₂).
Diatomic molecule: A molecule consisting of two atoms bonded together (e.g., O₂).