The elements present in the compound calcium sulfide are calcium (Ca) and sulfur (S). Calcium is a metal, while sulfur is a nonmetal. When these two elements combine, they form an ionic compound, with calcium losing two electrons to sulfur. This results in the formation of positively charged calcium ions (Ca2+) and negatively charged sulfide ions (S2-), which are then attracted to each other to form calcium sulfide (CaS).