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: CO 2 SENTENCES= Chemical Equations (shorthand description of chemical reaction)

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

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

7. 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 CO 2 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 + Cl 2 -> 2NaCl + energy Energy is GIVEN OFF/RELEASED Ex: light, thermal or electrical energy

13. Endothermic Reactions “endo-” = in Energy is ABSORBED 2H 2 O + energy -> 2H 2 + 0 2

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