Here's why:

* Reactivity: Chlorine is a highly reactive element, meaning it readily forms bonds with other elements.

* Stability: Chlorine atoms are more stable when they share electrons with another chlorine atom to form a covalent bond, creating a Cl₂ molecule.

* Gas at Room Temperature: At room temperature and pressure, chlorine exists as a pale green-yellow gas with a pungent, suffocating odor.

It's important to note that chlorine is not found in its pure elemental form in nature. Instead, it's usually found as compounds like sodium chloride (NaCl), which is table salt.