1. Mixtures, Elements, Compounds
Ch. 2.2 and 2.3
Mixtures, Elements, Compounds

2. Symbols Chemists use chemical symbols to represent elements
Chemical Symbol: 1st 1-2 letters of the name of the element
1st letter is Capitalized
2nd letter is lower case
Examples: Co = Cobalt; O = Oxygen;
Be = Berylium
Exception: Some use the letters from the Latin name
Examples: Fe = Iron (Ferrum)
K = Potassium (Kalium)
Cu = Copper (Cuprium)

3. Formulas Chemists use chemical formulas to represent compounds
Compounds: 2 or more elements
Examples: NaCl = Sodium Chloride
H2O = Water

4. Na + Cl2  NaCl Sodium + Chlorine  Table salt

5. H2 + O2  H2O

6. Distinguishing Substance and Mixtures

7. Heterogeneous V. Homogeneous

8. Identifying Substances
Physical Property: quality/condition of substance that can be observed or measured w/o changing substance.
Color, weight, size, volume
Physical Change: changing the state but not the composition.
Melting, boiling, vaporizing, freezing, crushing

9. Identifying Substances
Chemical Property: how does a substance react with another substance.
Iron reacts with oxygen.
Chemical Change: the reaction that takes place when two substances react. The composition changes. Also called a Chemical Reaction
Iron reacts with oxygen to make rust.

10. Paper chromatography Separating a mixture

11. Law of Conservation of Mass
During any chemical reaction or physical change, the mass of the products is always equal to the mass of the reactants
Bottom line: you cannot create or destroy matter. Matter is conserved.
What about burning wood?????