Properties of simple molecular substances. 1  Low melting and boiling points-This is because the weak intermolecular forces break down easily. 2  Non-conductive-Substances with a simple molecular structure do not conduct conduct: To allow electricity, heat or other energy forms to pass through.3  electricity.imple molecular substances are gases, liquids or solids with low melting and boiling points. The animation shows how the weak intermolecular forces between water molecules break down during boiling or melting: Your web browser does not have JavaScript switched on at the moment.