SrS is an ionic compound. This is because strontium (Sr) is a metal and sulfur (S) is a nonmetal. When a metal and a nonmetal bond, the metal will lose electrons to the nonmetal, creating positive and negative ions. These ions are then attracted to each other by electrostatic forces, forming an ionic bond.

In the case of SrS, strontium will lose two electrons to sulfur, creating Sr2+ and S2- ions. These ions are then attracted to each other, forming an ionic bond.