Physical Properties of Matter

1. Physical Properties of Matter

2. Types of Physical Properties • Physical properties are qualities that can be detected using our five senses or through a measuring device. • Examples of physical properties using in classification: • Strength • Hardness • Flexibility • Electrical conductivity • Thermal conductivity • Boiling point • Melting point • Density

3. Strength • The strength of a material refers to its ability to support a heavy load without breaking or tearing. • Examples of strong materials: concrete and steel. These are used in making buildings, roads and bridges. • Examples of weak materials: paper and cloth.

4. Hardness • The hardness of a material refers to its ability to withstand scratches. • A material will be able to cut or scratch a material softer than itself, but it cannot cut or scratch something that is harder.

5. Hardness • Diamond is the hardest substance that we know of. • It is used to cut glass, ceramic tiles and concrete. • Drills studded with diamonds can cut through rocks. This cutter is encrusted with diamonds and can be used to cut diamonds.

6. Flexibility • The flexibility of a material refers to its ability to bend without breaking and to return to its original shape and size. • A material that is not flexible is rigid. • E.g. of flexible objects: rubber bands, electrical wires and papers. • E.g. of rigid objects: tables, mirrors and computers.

7. Electrical conductivity • The electrical conductivity of a material is a measure of how readily electricity passes through it. • Substances that let electricity to pass through them easily are known as conductors. • Metals are good electrical conductors. • Materials that do not allow electricity to pass through them easily are called insulators or poor electrical conductors.

8. Electrical conductivity • Substances that do not allow electricity to pass through them easily are known as insulators or poor conductors of electricity. • Insulators are used to protect us from the harmful effects of electricity flowing through conductors (e.g. in wires).

9. Thermal conductivity • The thermal conductivity or heat conductivity of a material is a measure of how readily heat passes through it. • Materials that allow heat to pass through them easily are called heat conductors (e.g. metals). • Materials that do not allow heat to pass through them easily are called heat insulators or poor conductors of heat (e.g. plastic, ice).

10. Melting point • The melting point of a material refers to the temperature at which it changes in state from a solid to a liquid. • For example, the melting point of water is 0 0C. • Some substances have a very high melting point (e.g. iron melts at 1535 0C). • Some substances have a very low melting point (e.g. oxygen melts at – 218 0C).

11. Boiling point • The boiling point of a material refers to the temperature at which it changes in state from a liquid to a gas. • Different liquids have different boiling points.

12. Boiling point • The boiling point of water is 100 0C, while that of ethanol is 78 0C. • Some substances have a very low boiling point (e.g. liquid oxygen boils at – 183 0C). • Some substances have a very high boiling point (e.g. iron boils at 2750 0C).

13. Density • The density of a material refers to the ratio of its mass to its volume. • The same volume of a denser substance will have a greater mass than a less dense substance.