Every unique substance features different properties that are characteristic to it. These properties of matter can be classified as physical properties and chemical properties. Typically, a physical property of a substance can be observed or measured without requiring any changes in the composition of the substance (or in the identity of the substance, for that matter). However, the measurement of the chemical properties of a substance typically involves triggering a change in the composition or the identity of a substance. This is because the chemical properties of a substance are generally measured by triggering a chemical change.
Examples of the physical properties of substances include boiling point, melting point, and density. Examples of the chemical properties of substances include acidity and basicity, combustibility, and composition.