1. Classifying…
Chapter 2

2. Mixture vs. Pure
Pure substance – matter that has exactly the same makeup
Ex. Salt in a salt shaker
Mixture – matter that varies in its makeup
Ex. Salsa

3. Pure Substances
Element – pure substances that cannot be broken down into simpler substances
Represented by a chemical symbol
C – Carbon
O – Oxygen
Au – Gold
Atom – smallest particle of an element
Element contains only 1 type of atom

4. Pure Substances
Compound – pure substance made from 2 or more simpler substances
Ex. H2O = Hydrogen + Oxygen
Properties of compound differ from individual substances
H = gas… O = gas… together they make liquid water

5. Types of Mixtures Homogenous – parts evenly distributed throughout
Ex. Saltwater, brewed tea or coffee
Heterogeneous – noticeably different parts
Ex. Orange juice with pulp, chicken noodle soup

6. Solutions
Solutions – one substance dissolves in another to form a homogeneous mixture
Can’t filter out substances
Doesn’t separate into layers
Light passes through it
Doesn’t separate into layers – like oil and vinegar do (and they’re not a solution)

7. Topics Covered Physical properties Chemical properties
Properties of Matter
Topics Covered
Physical properties
Chemical properties

8. Physical & Chemical Properties
Physical properties – characteristics of a material that can be observed or measured without changing the makeup
Chemical properties – characteristics of a material that can be observed only when the substances change into different substances

9. Properties of Matter Viscosity Density Malleability Hardness
Conductivity
Melting Point
Boiling Point
Flammability
Reactivity
Physical Properties
Chemical Properties

10. Physical Properties Viscosity – resistance to flowing
Honey or oil (high viscosity)
Density – ratio of mass to volume
Floating objects are less dense (oil is less dense than vinegar)
Malleability – ability to bend (can hammer without shattering
Metal, clay
Density = mass/volume
Water’s density = 1g/mL (cm3) so anything less than that will float in water

11. Hardness – ability to scratch another material
Diamond cutting glass
Conductivity – ability to allow heat / electricity to flow
Metal spoon gets hot in pan
Melting Point – temperature at which solid  liquid (water melts at 0°C)
Boiling Point – temperature at which liquid  gas (water boils at 100°C)
Water melts at 32F and boils at 212F

12. Chemical Properties Flammability – ability to burn
Reactivity – how easily a substance combines with others
Reactivity – ex. Oil drum getting rusty
(Flamethrowers work by using compressed air to push a jellied, highly flammable fuel – napalm – out the barrel to where a small flame is already lit. The fuel mixture ignites and is pushed forward.)

13. Using Properties of Matter
To identify materials
Ex. At a crime scene (paint chips, metal pieces)
To choose the best materials for a job
Ex. You want to make a sneaker for running (material must be malleable, light weight…)
To separate materials
Filtration = separate material based on size
Distillation = separate material based on BP
BP = boiling point

14. Filtration

15. Distillation
Heat mixture to boiling point  becomes a gas, cools in the condenser (becoming a liquid), dripping into the flask to separate components

16. Physical & Chemical Changes
Chapter 2.3

17. Going Through Changes…
Physical change – change in the visible appearance, without changing the makeup of the material
Can be reversible or irreversible
Ex. Boil, melt, cut, bend, split, crack
Crumple a piece of paper, cut hair, slice a tomoato

18. Going Through Changes…
Chemical change – change where new substances are formed
Ex. Rust, burn, decompose, digest

19. Evidence of Chemical Change
Color change
Forms a gas (bubbles)
Forms a precipitate
Vinegar + milk = curdles
Burn paper
Picture is link to precipitation video – 30 secs (

20. Chemical or Physical??? Burning Wood Vinegar + Milk (Curdles)
Cutting Your Hair
Snowman Melting
Chemical, chemical, physical, physical

21. When Mentos candy is added to Coke, is it a chemical or physical change? How do you know?
Chemical change – forms bubbles (gas)
*Coke can picture is Mythbusters link (