However, it's important to note that chlorine exists in two main forms:

* Chlorine gas (Cl₂): This is the form you might think of when you hear the word "chlorine." It's a yellowish-green gas made up of two chlorine atoms bonded together.

* Chlorine ions (Cl⁻): This is the form chlorine takes when it dissolves in water or reacts with other elements. It has gained an extra electron, giving it a negative charge.

So, while chlorine is made up of only chlorine atoms, it can exist in different forms depending on how those atoms are bonded.