The correct formula for phosphorus triiodide is PI3. This compound consists of one phosphorus (P) atom and three iodine (I) atoms.
Phosphorus triiodide is classified as a molecular compound. This is because it is formed by the sharing of electrons between phosphorus and iodine atoms, which is characteristic of molecular compounds. In contrast, ionic compounds typically arise from the transfer of electrons from one atom to another, resulting in the formation of charged ions.
In PI3, phosphorus has a tendency to form covalent bonds with iodine. Since both elements are nonmetals, they share electrons to achieve a stable electron configuration, making PI3 a classic example of a molecular compound.