What kind of properties are only observed during a chemical change?

Chemical properties are properties that can only be observed during a chemical change. Unlike physical properties, which can often be identified without altering the substance's chemical composition, chemical properties require a reaction that transforms the substance into different substances. For instance, the flammability of a material or its ability to react with acid illustrates a chemical property because it only becomes apparent when the material undergoes a chemical transformation.

In contrast, physical properties such as color, phase, and density are measurable without changing the chemical identity of a substance. Intermolecular properties concern the forces between molecules and are also assigned to physical characteristics. Extensive properties, like mass and volume, depend on the amount of substance present, and do not reflect changes in chemical composition. Therefore, recognizing chemical properties is critical to understanding how substances behave under different conditions, especially during reactions that lead to new materials.