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) Light is released *new substance is always formed!!

4. Language of Chemistry

5. Letters Element Symbols ex: C

6. Chemical Formulas CO 2 Carbon dioxide H 2 O Dihydrogen oxide C 6 H 12 O 6 Sucrose

7. Chemical Equations shorthand description of a chemical reaction 2K + Cl 2 2KCl

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

9. IONIC Compounds Between a metal & nonmetal The metal loses electrons, the nonmetal gains electrons Balance ion charges Mg 2+ + Cl - = MgCl 2 M name 1 st then NM with ending changed to “-ide” Magnesium Chloride

10. COVALENT Compounds between nonmetals Share electrons 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

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

12. Balancing Equations Use COEFFICIENTS - # placed in front of a chemical symbol or formula Ex: 2 CO 2 means 2 molecules of carbon dioxide

13. Energy & Rate of Chemical Reactions

14. EVERY reaction involves ENERGY!! Energy is USED (absorbed) to break bonds Energy is GIVEN OFF as new bonds form

15. Type of Reaction depends on… Chemical energy of Reactants Chemical energy of Products VS.

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

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

18. Activation Energy Smallest amount of energy needed for substances to react

19. Factors Affecting Rates of Reaction

20. Temperature Higher Temp = faster rate of reaction

21. Concentration Higher concentration = faster reaction

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

23. 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