Any characteristic that can be used to describe or identify matter is called a property. Examples include volume, amount, odor, color, and temperature. Still other properties include such characteristics as melting point, solubility, and chemical behavior. For example, we might list some properties of sodium chloride (table salt) by saying that it melts at 1474 °F (or 801 °C), dissolves in water, and undergoes a chemical reaction when it comes into contact with a silver nitrate solution. Properties can be classified as either intensive or extensive, depending on whether the value of the property changes with the amount of the sample. Intensive properties, like temperature and melting point, have values that do not depend on the amount of sample: a small ice cube might have the same temperature as a massive iceberg. Extensive properties, like length and volume, have values that do depend on the sample size: an ice cube is much smaller than an iceberg. Properties can also be classified as either physical or chemical, depending on whether the property involves a change in the chemical makeup of a substance. Physical properties are characteristics that do not involve a change in a sample’s chemical makeup, whereas chemical properties are characteristics that do involve a change in chemical makeup. The melting point of ice, for instance, is a physical property because melting causes the water to change only in form, from solid to liquid, but not in chemical makeup. The rusting of an iron bicycle left in the rain is a chemical property, however, because iron combines with oxygen and moisture from the air to give the new substance, rust. Fallowing Table lists other examples of both physical and chemical properties.
