1. 2.1 Matter has observable properties
Chapter 2: Properties of Matter
2.1: Matter has observable properties
2.2: Changes of state are physical changes
2.3: Properties are used to identify substances
2.1 Matter has observable properties
Have learned…
Matter has mass and volume
Matter is made of atoms
Matter exists in different substances
Will learn…
Physical and chemical properties
Physical changes
Chemical changes

2. Physical Properties Examples?
Color, shape, size, texture, volume, mass
Take a piece of clay or play-doh
What physical properties change?
Shape changed, color/texture/mass/volume stay same
Is it still play-doh?

3. Physical Properties Play-doh: did the density stay the same?
Mass = 200 g, Volume = 100 cm3 = 100 mL
Density = Mass/Volume = 2 g/ cm3
Break mass in half: 100 g & 100 g
Volume?
50 mL & 50 mL
New total mass, volume, density?
200 g, 100 mL, 2 g/cm3
200g/100mL = 2 g/cm3 ; 100g/50mL = 2 g/cm3

4. Density
For any substance, the amount of mass in a “unit” of volume is constant
Does density change after a state (of matter) change?
If density = 6 g/cm3 and volume = 12 cm3, what is the mass of the object?

5. Physical Changes
Is breaking off a piece of clay a physical change or a chemical change?
No change in the physical property of the substance itself – still clay
Liquid water to ice?
Still H2O

6. Physical Changes
Book: Sheep – sheering spinning dyeing – all physical changes – Original substance remains the same.

7. Chemical Changes Wood burning to ashes – new substance
New substance released into the air
Chemical Properties – combustibility, ability to rust, tarnish (Statue of Liberty – copper changes to blue-green when exposed to air)

8. Chemical Changes Substance is affected
Combination of atoms are rearranged to form a new substance
Ex: Iron plus oxygen = rust!
4Fe(s) + 3O2(g) --> 2Fe2O3(s)
Ex: Antacid in water
Ex: Cooking an egg (and digestion)
**True indication of a chemical change?
A new substance has been formed

9. Signs of a Chemical Change
(Can you see them all?)
Production of an odor – egg rotting (sulfer)
Change in temperature – burning log
Change in color – fruit ripening
Formation of bubbles - antacid
Formation of a solid – two liquid combined to form a solid – calcium carbonate precipitates in shells
Ca+2(aq)+2HCO3-(aq)↔CaCO3(s)+CO2 (g)+ H2O(l)