What is common to the following elements lithium carbon oxygen and fluorine?

Lithium, carbon, oxygen, and fluorine are all reactive elements, which means that they want to bond with other elements to form compounds. Carbon and oxygen together can even covalently bond together to form the compound CO2 (carbon dioxide). Lithium and fluorine can ionically bond because lithium needs to lose its single valence electron to take away its unnecessary second energy shell to finish with a single full energy shell, while fluorine needs to gain one more valence electron to make its last energy shell full, forming the compound LiF (lithium fluoride).