You can use the periodic table to help you understand why some atoms form molecules while others do not. Argon and chlorine are both nonmetals.
Argon exists in nature as individual argon atoms. Chlorine exists in nature as
two chlorine atoms covalently bonded to each other. Why does this occur?

A. Argon is unstable, so it does not share electrons with other atoms like
chlorine does.
B. Argon cannot form covalent bonds because it already has
an even number of valence electrons.
C. An argon atom is already stable, but
a chlorine atom only becomes stable when it transfers an electron to another
chlorine atom.
D. An argon atom is already stable with eight valence
electrons, but a chlorine atom must share two electrons with another chlorine
atom to reach eight valence electrons and become stable.