Group 1 elements are likely to react with chlorine to form XCl compounds. Group 1 elements, also known as alkali metals, have one valence electron in their outermost shell. This makes them highly reactive and eager to lose this electron to achieve a stable electron configuration. When they react with chlorine, which has seven valence electrons and needs one more to attain a full outer shell, they readily transfer their outermost electron to chlorine, resulting in the formation of ionic compounds with the general formula XCl, where X represents the group 1 element.