When silver (Ag) and sulfur (S) react, they form silver sulfide (Ag2S). The chemical equation for this reaction is:

2Ag + S → Ag2S

In this reaction, two atoms of silver react with one atom of sulfur to produce one molecule of silver sulfide. Silver sulfide is a black, crystalline compound that is insoluble in water. It is commonly found in nature as the mineral argentite.