What bond does calcium and sulfur for?

Calcium and sulfur form an ionic bond. Calcium, a metal, loses two electrons to achieve a stable electron configuration, becoming a positively charged calcium ion (Ca²⁺). Sulfur, a non-metal, gains those two electrons to become a negatively charged sulfide ion (S²⁻). The electrostatic attraction between these oppositely charged ions results in the formation of calcium sulfide (CaS).