1. Physical Properties
Chapter 2 Section 2

2. Physical Properties
Physical Property – any characteristic of a material that can be observed or measured without changing the composition of the substances in the materials.
Viscosity
Conductivity
Malleability
Hardness
Melting point
Boiling point
Density

3. Viscosity Resistance to flowing
The greater the viscosity = slower the liquid moves
Thin liquids have low viscosity
Water
Vinegar
Thick liquids have high viscosity
Honey
Corn Syrup

4. Viscosity Viscosity usually decreases when it is heated
Why is viscosity important?

5. Conductivity A material’s ability to allow heat to flow
Materials with high conductivity such as metals are called conductors
If a material is a good
conductor of heat it is
usually a good conductor of
electricity

6. Malleability
The ability of a solid to be hammered without shattering .
Most metals are malleable.

7. Hardness
Compare the hardness of two materials by seeing which material can scratch the other.
Diamond is the hardest known material.

8. Melting and Boiling Points
Melting point: the temperature at which a substance changes from solid to liquid
Boiling point: the temperature at which a substance boils
Water MP= 0°C
Water BP = 100°C

9. Density Density can be used to test the purity of a substance
Ratio of the mass of a substance to its volume
Equation for density D = M/V

10. Using Physical Properties
Physical properties are used to:
Identify a material
Choose a material for a specific purpose
To separate the substances in a mixture

11. Separation Methods
Filtration – the process that separates materials based on the size of their particles
Distillation – a process that separates the substances in a solution based on their boiling points

12. Recognizing Physical Changes
Physical change – occurs when some of the properties of a material change but the substances in the material stay the same
Some physical changes can be reversed others cannot be reversed
Examples of physical changes
Melting butter in a pan
Crumpling paper
Slicing a tomato
Braiding hair
Peeling an orange

13. Reviewing Concepts List 5 examples of physical properties
Describe 3 uses of physical properties
Name two procedures that are used to separate mixtures
When you describe a liquid as thick, are you saying that it has high or low viscosity?
Explain why sharpening a pencil is a physical change.
What allows a mixture to be separated by distillation?

14. Chemical Properties
Chapter 2 Section 3

15. Chemical Property
Any ability to produce a change in the composition of matter.
Can be observed only when the substances in a sample of matter are changing into different substances.
Examples:
Flammability
Reactivity

16. Flammability A material’s ability to burn in the presence of oxygen.
Sometimes flammability is a desirable property (gasoline, firewood)
Other times flammability is not desirable (fabrics for pajamas)

17. Reactivity
How readily a substance combines chemically with other substances
Examples
Oxygen – high reactivity
Nitrogen – low reactivity

18. Chemical Change
Occurs when a substance reacts and forms one or more new substances
Three common types of evidence for a chemical change:
Change in color
Production of a gas
Formation of a precipitate

19. Change in Color Examples: Leaves changing color in the fall
Ripening of a banana peel
Silver bracelet exposed to air darkens
Match that burns turns black
Copper changing when exposed to moist air (patina)

20. Change in Color A new copper roof has a reddish color
An old copper roof has a greenish color

21. Production of a Gas
Carbon dioxide gas forms when vinegar is mixed with baking soda
Baking powder in a cake causes a cake to rise
Baking soda and acids react when wet, cake bakes, bubbles of CO2 expand, cake rises

22. Formation of a Precipitate
Precipitate – any solid that forms and separates from a liquid mixture
Example: curds in cottage cheese – form when an acid is added to milk

23. Is a Change Chemical or Physical?
Are different substances present after the change takes place?
NO – change is PHYSICAL
YES – change is CHEMICAL
When matter undergoes a chemical change the composition of matter changes.
When matter undergoes a physical change the composition of matter remains the same.

24. Reviewing Concepts
List three common types of evidence for a chemical change.
How do chemical changes differ from physical changes?
Gold and platinum are often used to make jewelry. What can you infer about the reactivity of these elements?
A piece of butter melts and then burns in a hot frying pan. Which of these changes is physical and which is chemical?