I believe the correct term would be chemical . In order to observe a chemical property of a substance, the substance must interact with another substance , such as when gasoline burns or when sodium metal reacts with water. Chemical properties are the characteristics of a certain substance that is can be observed only during a reaction wherein the total identity of the original substances are being altered into new species with new set of properties. These properties are toxicity, stability, heat of combustion, flammability, coordination number, heat of formation, oxidation state, the chemical bonds present and reactivity. These properties can be measured only by allowing chemical reactions to occur.