Here's why:

* Electronegativity: Both phosphorus and sulfur are nonmetals, and their electronegativity values are relatively close. This means they have similar tendencies to attract electrons.

* Sharing Electrons: Instead of one atom completely taking an electron from the other (ionic bonding), they share electrons to achieve a stable outer shell configuration.

Examples:

* Phosphorus trisulfide (P₂S₃): A common compound used in matches.

* Phosphorus pentasulfide (P₂S₅): Used in the production of lubricants and other industrial chemicals.

Let me know if you have any other chemistry questions!