Characteristics that help us to distinguish one type of matter from another are referred to as properties. Matter exhibits two types of properties: physical and chemical.
Physical properties of matter can be measured and observed without changing the composition or identity of the matter. Odor, taste, color, appearance, hardness, density, melting and boiling points, and electrical conductivity, are all examples of physical properties.
Some of these physical properties can be observed without changing the physical state of the matter. So, when we say that helium gas is lighter than air, we are referring to a physical property. Similarly, the smell of gasoline is also a physical property.
Other physical properties can only be observed when matter undergoes physical changes. For example, pure gold in its solid-state is made up of tightly packed gold atoms. But when it is melted at a high temperature, it changes its state from a solid to a liquid. However, this liquid is still composed of gold atoms, so this is a physical change.
Similarly, when liquid water freezes to solid ice, the chemical composition of both the water and ice remains the same. Thus, physical changes only alter the state of the matter or physical conditions, without changing the chemical composition.
Crushing, grinding, slicing, blending, magnetizing, or demagnetizing are other common ways to change the physical condition of matter.
Chemical properties of matter, on the other hand, are characteristics that can only be measured and observed when the substance has a change in chemical composition. Corrosiveness, flammability, toxicity, acidity, or chemical reactivity are all examples of chemical properties of matter.
In order to identify a chemical property, we look for a chemical change. Chemical changes involve chemical reactions and are often observed through a change in color or odor.
For example, when a copper penny is exposed to air and water there is a chemical change. The copper undergoes a series of chemical reactions, one of which is shown here, to form a layer of blue-green patina on an otherwise naturally brown penny.
Thus, chemical changes produce entirely new forms of matter which differ from the matter present before the change. For instance, the flammability of gasoline is a chemical property evident from the chemical changes in the composition of gasoline when it burns, turning gasoline into entirely new substances, primarily carbon dioxide and water.
