Characteristics of Covalently Bonded Substances

Covalently bonded substances, or molecules, have significantly lower melting and boiling points than ionic compounds. If ionic compounds can be described as hard and brittle, covalent compounds can be described as soft and squishy.  Covalent compunds exist as gases, volatile liquids, or soft solids.  The state the substance is in depends on the bond energy of the substance.  If the bond energy is low, the substance is a gas.  If the bond energy is moderate, then the substance is a volatile liquid.  If the bond energy of the substance is very high, then it is a soft solid. This is because the atoms in a molecule aren't fixed in one place. They are able to move around and remain bonded. A good example of this is a playground ball pit. While the balls themselves are held together very tightly (like the molecules), the balls aren't stuck to each other.  Covalent compounds do not conduct electricity in water, electricity is conducted in water through the movement of ions from place to place. Covalent compounds also generally don't dissolve well in water. This happens because water is polar, and most covalent compounds are mostly non-polar. There are exceptions, of course. Molecular shape can affect a substance's properties. The shape of a molecule can affect its polarity. A molecule's (that has more than two atoms) polarity is determined by the polarity of each bond and the way each bond is arranged. In turn, the polarity of a molecule affects the properties of the molecule.