Chapter 17

List the properties of a substance that would definitely establish that it is an ionic material.

If we classify substances as ionic, molecular, macromolecular, or metallic, in which (if any) categories are all the members a. soluble in water? b. electrical conductors in the melt? c. solids at room temperature? d. insoluble in all common solvents?

A given substance is a white, granular solid at \(25^{\circ} \mathrm{C}\) that does not conduct electricity. It melts at \(250^{\circ} \mathrm{C}\) then decomposes to a black goo at \(312^{\circ} \mathrm{C}\). As a liquid it does not conduct electricity, not even an alternating current. It does not dissolve in water, but dissolves readily in hexane to produce a solution that does not conduct electricity. What would the proper classification of the substance be, based on this information?

A dull gray-white solid melts at \(1650^{\circ} \mathrm{C}\). It is not electrically conductive as either a solid or a liquid, and is not soluble in either water or any organic solvent. Classify the substance as best you can from these properties.