Spring 2001 Dr. Barber . Identify atoms and ions from their electronic configurations. Know size trends in the periodic table and know how they are related to the quantum rules and electronic configurations.
Reality is that there is a gradual progression from pure ionic to pure covalent molecules.
Polar covalent bonds have EN between 0.4 and 1.7. If EN difference is zero, the bond is nonpolar covalent. This is an useful but arbitrary cut off. For a molecule to be polar it must meet two requirements. It must have polar bonds.