Final answer:
PCl₃ (phosphorus trichloride) is a polar covalent compound due to the significant difference in electronegativity between phosphorus and chlorine atoms. The molecule exhibits dipole-dipole attractions and can interact with polar solvents like water. Its polarity also results in a higher boiling point compared to nonpolar compounds.
Step-by-step explanation:
A polar covalent compound is a compound in which there is a significant difference in electronegativity between the bonded atoms, resulting in an uneven distribution of electron density. In the case of PCl₃ (phosphorus trichloride), phosphorus (P) has a greater electronegativity compared to chlorine (Cl). As a result, the chlorine atoms exert a greater pull on the shared electrons, creating partial positive and partial negative charges within the molecule.
This uneven distribution of charge makes PCl₃ a polar molecule. The electronegativity difference between chlorine and phosphorus causes a dipole moment, with the chlorine atom acquiring a partial negative charge and the phosphorus atom acquiring a partial positive charge. This polarity allows the PCl₃ molecules to interact with other polar molecules through dipole-dipole attractions.
For example, PCl₃ is soluble in polar solvents such as water because the partial positive charges on the phosphorus atom can attract the partial negative charges of the solvent molecules. Additionally, the presence of polar bonds and dipole-dipole attractions gives PCl₃ a higher boiling point compared to nonpolar compounds of similar molecular weight.