NANTeL Chemistry Certification – Engineering Fundamentals Practice Test

Covalent compounds are made of molecules held together by covalent bonds, so they don’t form free ions easily. This leads to two typical trends: weaker forces between molecules compared to ionic lattices, and lack of charged particles to carry current. As a result, they usually melt and boil at lower temperatures than ionic substances, and they don’t conduct electricity in either the solid or melted state (they’re often non-electrolytes when dissolved). There are exceptions—some covalent substances can ionize in water (like certain acids) or exist as network solids with high melting points—but the general pattern for covalent compounds is lower melting points and nonconductivity. The other statements describe ionic behavior (high melting points with SAMPLEmolten conductivity or complete ionization in water), which doesn’t fit covalent compounds as a broad rule.