1. Chemical Reactions
Processes by which one or more substances change to produce one or more different substances

2. Chemical bonds are broken & formed

3. Indicators (clues) Change in color Gas formed (bubbles)
Change in temperature (energy taken in or given off)
Precipitate (solid formed in a solution)
*NEW substance is always formed!!

4. Language of Chemistry LETTERS= Element Symbols ex: C
WORDS= Chemical Formulas ex: CO2
SENTENCES= Chemical Equations
(shorthand description of chemical reaction)

5. for COVALENT Compounds
(between Nonmetals)
Use prefixes to tell how many of each element
Ex: CO2 = carbon dioxide
N2O = dinitrogen monoxide
Mono- 1
Hexa- 6
Di- 2
Hepta- 7
Tri- 3
Octa- 8
Tetra- 4
Nona- 9
Penta- 5
Deca- 10

6. IONIC Compounds
(between M & NM) Balance ion charges Mg 2+ + Cl - = MgCl2 Metal name 1st then NM with ending changed to “-ide” Magnesium Chloride

7. Reactants = starting materials
Reactants = starting materials = yield sign (similar to equal sign) Products = substances formed Reads as “Potassium and chlorine react to yield potassium chloride”

8. Law of Conservation of Mass
Mass is neither created nor destroyed
Mass of the reactants =
mass of products

9. Balancing Equations
Use COEFFICIENTS = # placed in front of a chemical symbol or formula Ex: 2 CO2 means 2 molecules of carbon dioxide

10. Energy & Rate of Chemical Reactions

11. EVERY reaction involves ENERGY!!
Energy is USED (absorbed) to break bonds
Energy is GIVEN OFF as new bonds form
Type of Reaction depends on…
Chemical energy of REACTANTS VS
Chemical energy of PRODUCTS

12. Exothermic Reactions “Exo-” = out “Therm-” = heat
2Na + Cl2 -> 2NaCl + energy
Energy is GIVEN OFF/RELEASED
Ex: light, thermal or electrical energy

13. Endothermic Reactions
“endo-” = in
Energy is ABSORBED
2H2O + energy ->
2H2 + 02

14. Factors Affecting Rates of Reaction

15. Temperature
Higher Temp = faster rate of reaction

16. Concentration
Higher concentration = faster reaction

17. Surface Area (amount of exposed surface)
Greater Surface Area = Faster Reaction

18. Catalyst
Speeds up reaction without being permanently changed
Lowers activation energy
Ex: enzymes in body
Inhibitor
Slows down or stops a chemical reaction
Ex: preservatives in food