Ionic compounds have electropositive and electronegative elements present and high melting points due to strong ionic bonding. Polar molecules have weak intermolecular dipole-dipole interaction and dispersion forces, and low melting points. Nonpolar molecules have weak intermolecular forces, and low melting points. LiF - ionic compound ionic bonding BeF2 - ionic compound ionic bonding BF3 - nonpolar molecule dispersion force CF4 - nonpolar molecule dispersion force NF3 - polar molecule dispersion force dipole-dipole interaction OF2 - polar molecule dispersion force dipole-dipole interaction F2 - nonpolar molecule dispersion force Solution Ionic compounds have electropositive and electronegative elements present and high melting points due to strong ionic bonding. Polar molecules have weak intermolecular dipole-dipole interaction and dispersion forces, and low melting points. Nonpolar molecules have weak intermolecular forces, and low melting points. LiF - ionic compound ionic bonding BeF2 - ionic compound ionic bonding BF3 - nonpolar molecule dispersion force CF4 - nonpolar molecule dispersion force NF3 - polar molecule dispersion force dipole-dipole interaction OF2 - polar molecule dispersion force dipole-dipole interaction F2 - nonpolar molecule dispersion force.