Overview
This lecture explains the differences between physical and chemical properties of matter, including definitions, examples, and related concepts like physical and chemical changes.
Physical Properties of Matter
- Physical properties can be observed without changing the substance’s chemical identity.
- Physical properties are divided into intensive and extensive properties.
- Intensive properties do not depend on the amount of the substance (e.g., color, density, boiling point, melting point).
- Extensive properties depend on the amount of the substance (e.g., mass, volume).
Examples of Intensive and Extensive Properties
- The color and density of water remain the same regardless of the quantity.
- Boiling and melting points of water are unchanged even if more water is added.
- Mass and volume of water increase when more water is added, showing extensive properties.
Chemical Properties of Matter
- Chemical properties are observed only when the substance’s molecular structure changes.
- Examples include heat of combustion (energy released when burning with oxygen) and flammability (ability to burn when exposed to flame).
Physical and Chemical Changes
- Physical change: substance changes state but can revert to original form (e.g., ice melting to water and freezing back to ice).
- Chemical change: substance changes its atomic structure and cannot return to its original form (e.g., wood burning to ash).
Key Terms & Definitions
- Physical Property — characteristic observed without changing chemical identity.
- Chemical Property — characteristic observed by changing molecular structure.
- Intensive Property — does not depend on substance amount (color, density).
- Extensive Property — depends on substance amount (mass, volume).
- Physical Change — change in state, reversible.
- Chemical Change — change in structure, irreversible.
Action Items / Next Steps
- Review examples of intensive and extensive properties in everyday materials.
- List additional examples of physical and chemical changes.