Ductility is a physical property of matter, as it can be measured or observed without the substance undergoing a chemical change. Ductility is the ability of a solid material to stretch under tensile stress, for example when a metal is stretched into a wire. The chemical nature of the metal isn't changed in this case. When you're trying to distinguish between chemical and physical properties, keep in mind that chemical properties are generally only observable when a material undergoes a chemical change. Examples of chemical properties are flammability, tendency to corrode and reactivity with a particular class of chemicals. A chemical property of most metals is that they react with acids. Some examples of physical properties, which don't involve chemical change, are melting and boiling points, density and color.