1. 18.2 – Properties of Matter

2. Objectives Identify substances using physical properties.
Contrast physical and chemical properties
Compare and contrast physical and chemical changes.
Identify chemical changes.
Determine how the law of conservation of mass applies to chemical changes.

3. Properties
Physical – characteristics that can be observed without altering identity of substance
Density, color, melting point
Chemical – characteristics that cannot be observed without altering identity of substance
Flammability

4. Changes in matter Physical – alterations in form but not matter itself
Does not alter identity
Tear, Break, Grind, Dissolve, Freeze, Melt, Boil, Distill, Crush
Chemical – does alter identity
Produces different substance
Burn, Cook, Rust, Decay, Digest

5. Distillation

6. Signs of Chemical Change
Color Change
Bubbles – gas produced
Odor change
Temperature change
Precipitate forms – new solid made

7. Weathering
Forces of nature are continuously shaping the Earth’s surface
Rocks split
Deep canyons are carved out
Sand dunes shift
Curious limestone formations decorate caves
Physical & Chemical Change

8. Weathering - Physical
Large rocks split as water seeps through small cracks
Water freezes and expands
Smaller pieces of newly exposed rock still have same properties of original rock

9. Weathering - Chemical
Limestone, calcium carbonate, does not dissolve easily in water
If water is slightly acidic because of the presence of carbon dioxide it reacts with limestone
This change creates a new substance, calcium hydrogen carbonate, which dissolves in water

10. Weathering - Chemical
Similar chemical change produces caves and icicle shaped rock formations

11. Law of Conservation of Mass
Mass is neither created nor destroyed when chemical and physical changes occur
Applies throughout universe and in all branches of science

12. Lavoisier Created with determining law of conservation of matter/mass
First to recognize the role of oxygen in burning and rusting
Guillotined during French Revolution

13. In-Class Assignment/Homework
Learning Target Inventory
Column
18.2 WKT