1. Properties and Changes of Matter
Chapter 20

2. Properties of Matter

3. Physical and Chemical Properties
Section 1

4. Physical Properties

5. Physical Properties Physical properties
characteristics you can observe without changing the composition of the substance
some are observed using your 5 senses
how something looks, smells, sounds or tastes
examples – color, odor, shape, texture, state of matter

6. Physical Properties Size-Dependent Properties
property depends on the size of the sample
property changes if the sample gets bigger or smaller
examples:
Volume – amount of space an object occupies; multiple the length X width X height = (cm3)
Mass - how much matter an object contains (g)
Weight - force of gravity on an object (N)

7. Physical Properties Size-Independent Properties
property does not depend on the size of the sample
property does not change if the size of the sample changes
examples:
density – amount of mass in a given volume
D = M ÷ V = (g/cm3)

8. Physical Properties examples:
solubility – number of grams of one substance that will dissolve in 100 g of another substance
melting point – temperature when a solid changes into a liquid
boiling point – temperature when a liquid turns into a gas
magnetism – substance pulls iron towards it

9. Physical Properties examples:
ductility (ductile) – ability to be made into wires, like copper

10. Physical Properties examples –
elasticity – the ability to stretch and not break

11. Physical Properties examples:
malleability – ability to be hammered into sheets (like gold)

12. Chemical Properties

13. Chemical Properties chemical properties –
characteristic that cannot be observed without altering the substance
examples:
flammability – ability to burn
tendency to rust – oxidize, exposure to oxygen and water
reactivity – reacts with other materials to cause a change in substance

14. Section 1 Review
How are your senses important for identifying physical properties of matter?
It is through the senses that you gather information about the world around you. For example, you use your senses to detect an object’s shape, color, texture, taste, sound, temperature, smell, weight, state and behavior, as well as to make measurements.

15. Section 1 Review Describe the physical properties of a baseball.
A baseball is a solid, its shape is spherical, its texture is smooth yet bumpy near the stiches, its color is red and white. If I had the right tools, I could measure its mass, volume and density.

16. Section 1 Review
Explain why solubility is a size independent physical property.
Solubility is a ratio of two size dependent properties. As one property increases, so does the other one. The ratio does not change.

17. Section 1 Review How do chemical and physical properties differ?
A physical property can be observed without changing the composition of the substance. A chemical property cannot be observed without altering the composition of the sample.

18. Physical and Chemical Changes
Section 2

19. Physical Changes

20. Physical Changes form or appearance of matter changes
composition does not change
still made from the same elements

21. Physical Changes

22. Physical Changes Examples
Changing shape – only changes the form of matter
cut
tear
bend
crumple

23. Physical Changes

24. Physical Changes Examples
Dissolving– particles spread out in a solution
composition stays the same
only form changes

25. Physical Change Examples Changing states
vaporization or evaporation – liquid to gas
condensation – gas to liquid
sublimation – solid to gas
deposition – gas to solid

27. Chemical Changes

28. Chemical Changes substance is changed into another substance
composition changes
changed at a molecular level

29. Chemical Changes

30. Chemical Changes Signs of a Chemical Change color changes
leaves undergo chemical change in fall
apple turns brown when exposed air
marshmallow or bread turns brown when toasted

31. Chemical Changes

32. Chemical Change Signs Exothermic = Release heat. Gets warm.
energy either absorbed or released
light is given off (flame)
temperature changes (heats up or cools down)
sound produced (explosion)
Exothermic = Release heat. Gets warm.
Endothermic = Absorb heat. Gets cold.

33. Chemical Changes

34. Chemical Change Signs odor changes new smell is produced
the smell of spoiled milk
rotting eggs
the way the air smells after a thunderstorm

35. Chemical Changes

36. Chemical Changes Signs gases or solids (precipitate) are produced
bubbles form – gas produced
solid forms from liquids, like spoiled milk

37. Chemical Changes Signs not easily reversed
cannot be changed back into its original substance by physical means
substance that existed before the chemical change no longer exists

38. Section 2 Review
List five physical changes that you can observe in your home.
Physical changes at home could include cutting paper, pouring milk on cereal, mowing the lawn, melting ice. None of these change the composition of the material.

39. Section 2 Review
Determine what kind of change occurs on the surface of bread when it is toasted.
The toast is an example of a chemical change. The bread’s color and odor changes and energy.

40. Section 2 Review How is mass conserved during a chemical change?
The particles within matter are rearranged, but the total mass of the matter remains the same.

41. Section 2 Review
A log is reduced to s small pile of ash when it burns. Explain the difference in mass between the log and the ash.
The difference in mass is a result of the mass of gas that was formed in the reaction and escaped.