1. Chapter 2

2. Matter matter – anything that has mass and takes up space
Matter consists of atoms and molecules in motion.

5. Pure Substances

6. Pure Substances Pure substances – made of one kind of material
1) element – substance that cannot be broken into simpler substances
on periodic table
2) compound – two or more elements bonded together
Often represented by chemical formula: H2O, C6H12O6
has a new set of properties

7. Example: Element vs. Compound

8. Mixtures

9. Mixtures
mixture – blend of two or more substances; not bonded together
components retain their individual properties

10. Two Types of Mixtures
1) heterogeneous mixture – not evenly mixed; can see the different parts
Ex. peas & carrots, salt & pepper, sand & water

11. Two Types of Mixtures
2) homogeneous mixture – evenly mixed; you cannot see individual parts
AKA “solutions” –must be in liquid or gas state at one point
Ex. sugar water, Koolaid, Jello

12. Example: Homogeneous & Heterogeneous Mixtures

13. Mixtures Alloy – two metals melted and blended, then hardened
homogeneous
Ex. brass, bronze, steel

14. Mixtures
Note: Elements cannot be stirred together to form a compound. It requires a lot of heat and/or pressure to make a bond.

15. Mixtures
Reflection:
If you have a container with hydrogen gas and oxygen gas in it, do you have water?
Why or why not?

16. Law of Conservation of Mass
Law of Conservation of Mass – matter cannot be created or destroyed
mass at beginning = mass at end

17. Properties and Changes
Physical vs. Chemical
Properties and Changes

18. Physical
Chemical
can be observed without changing the identity of the substance
change in form/appearance, but chemical make-up stays the same
cannot be observed unless identity is changed
chemical make-up is changed, cannot be changed back to original (generally)

19. Physical Properties & Changes
melting
boiling
magnetism
conductivity- ability to conduct electric current 
malleability- flattened into thin sheets without cracking
ductility- ability to be pulled into wires w/o breaking
phase changes
dissolving
recycling

20. Physical Properties Density = mass volume
Example: metals of the same volume do not have the same mass
Aluminum = 2.70 g/mL
Iron = 7.87 g/mL

21. Chemical Properties reactivity – quickly undergoes changes
flammability – ability to combust
inert – unreactive
rust
corrosion
oxidation
combustion
cooking
rotting
Other Examples:
Cake baked with flour, water, and sugar cannot be separated back into ingredients

22. Practice ID Phys & Chemical
Acid rain corroding the statue of liberty
Dissolving salt in water
Boiling salt water until just salt remains
Melting steel
A car rusting
Cracking ice
Food digesting

23. Separation Techniques
Methods to separate the components of a mixture

24. Separation Techniques
filtration – mixture poured through porous paper

25. Separation Techniques
decanting – pouring a solution without disturbing solid on bottom

26. Separation Techniques
chromatography – components travel across the surface of a paper at different rates

27. Separation Techniques
centrifugation – machine spins mixture to separate a solid to the bottom of a tube

28. Separation Techniques
crystallization – solid crystals form out of a solution

29. Separation Techniques
electrolysis – using an electric current to break apart a compound

30. Separation Techniques
distillation – separating liquids based on differing boiling points and condensing the vapors