18 Physical and Chemical Properties of Matter
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Physical and Chemical Properties of Matter
Properties of matter can be classified as either extensive or intensive and as either physical or chemical.
LEARNING OBJECTIVES
Recognize the difference between physical and chemical, and intensive and extensive, properties.
KEY TAKEAWAYS
Key Points
- All properties of matter are either physical or chemical properties, and physical properties are either intensive or extensive.
- Extensive properties, such as mass and volume, depend on the amount of matter being measured.
- Intensive properties, such as density and color, do not depend on the amount of the substance present.
- Physical properties can be measured without changing a substance’s chemical identity.
- Chemical properties can be measured only by changing a substance’s chemical identity.
Key Terms
- intensive property: Any characteristic of matter that does not depend on the amount of the substance present.
- extensive property: Any characteristic of matter that depends on the amount of matter being measured.
- physical property: Any characteristic that can be determined without changing the substance’s chemical identity.
- chemical property: Any characteristic that can be determined only by changing a substance’s molecular structure.
All properties of matter are either extensive or intensive and either physical or chemical. Extensive properties, such as mass and volume, depend on the amount of matter that is being measured. Intensive properties, such as density and color, do not depend on the amount of matter. Both extensive and intensive properties are physical properties, which means they can be measured without changing the substance’s chemical identity. For example, the freezing point of a substance is a physical property: when water freezes, it’s still water ([latex]\text{H}_2\text{O}[/latex])—it’s just in a different physical state.
A chemical property, meanwhile, is any of a material’s properties that becomes evident during a chemical reaction, that is, any quality that can be established only by changing a substance’s chemical identity. Chemical properties cannot be determined just by viewing or touching the substance; the substance’s internal structure must be affected for its chemical properties to be investigated.
Physical Properties
Physical properties are properties that can be measured or observed without changing the chemical nature of the substance. Some examples of physical properties are:
- color (intensive)
- density (intensive)
- volume (extensive)
- mass (extensive)
- boiling point (intensive): the temperature at which a substance boils
- melting point (intensive): the temperature at which a substance melts
Chemical Properties
Remember, the definition of a chemical property is that measuring that property must lead to a change in the substance’s chemical structure. Here are several examples of chemical properties:
- Heat of combustion is the energy released when a