Which term describes a chemical compound whose smallest discrete units are molecules?

• A. Molecule
• B. Chemical Formula
• C. Bond Energy
• D. Molecular Compound

Answer: (D)

Think about what defines the basic building block of a substance. If the smallest discrete unit that repeats in the solid, liquid, or gas phase is a molecule, the substance is a molecular compound. This happens when atoms share electrons through covalent bonds, typically between nonmetals, producing distinct molecules such as H2O, CO2, or CH4. Because the units are whole molecules, molecular compounds usually have lower melting points and do not conduct electricity as solids. In contrast, ionic compounds are built from a lattice of ions, and their smallest repeating unit is a formula unit, not a molecule. That distinction is why the term describing a compound whose smallest discrete units are molecules is molecular compound.