–Chemical reactions occur when bonds between the outermost parts of atoms are formed or broken

–Chemical reactions involve changes in matter, the making of new materials with new properties, and energy changes.

–Symbols represent elements, formulas describe compounds, chemical equations describe a chemical reaction

Items to the LEFT of the arrow in a chemical equation are called REACTANTS. Na + Cl NaCl

Items to the right of the arrow are called PRODUCTS. Ex: Na + Cl NaCl

Important NOTE: No matter how many reactants and products are involved, all atoms present at the start of a reaction are present at the end.

THE TOTAL MASS OF THE REACTANTS MUST EQUAL THE TOTAL MASS OF PRODUCTS. MATTER IS NEVER CREATED OR DESTROYED.

Reactions that release heat.

Reactions that absorb heat.

A substance that speeds up chemical reactions.

A substance that slows down a chemical reaction.

Synthesis reaction- 2 or more simple substances combine to form a new, more complex substance

Na + Cl NaCl Na 2 O + CO 2 Na 2 CO 3

Decomposition reaction- A complex substance breaks down into two or more simpler substances Starts with one reactant and ends with 2 or more products.

H 2 CO 2 H 2 O +CO NaCl Na + Cl 2

Single-replacement reaction – An uncombined element replaces an element that is part of a compound.

One compound and a free element that recombine to yield a new compound and new free element.

2Na +2H O 2NaOH + H Fe + CuSO 4 Cu + FeSO 4

Double-replacement reaction- different atoms in 2 different compounds replace each other. 2 compounds react to form 2 new compounds.

Starts with 2 compounds as reactants. These recombine to form 2 new compounds as products. + +

MgCO + H 2 Cl MgCl + H 2 CO KOH + HNO 3 HOH + KNO 3 C:\Documents and Settings\mswilliams\Local Settings\Temporary Internet Files\OLK1B5\types.htm

C + O  CO 2 1. Synthesis Reaction

NaCl ----  Na + Cl 2 2. Decomposition Reaction

3. FeCl 2 + K 2 S --  FeS + KCl Double Replacement

4. Fe + H 2 O  Fe 3 O 4 + H 2 Single Replacement

5. AlCl 3  Al + Cl 2 Decomposition Reaction

6. Na + H 2 SO 4 ---> Na 2 SO 4 + H 2 Single Replacement

7. AlCl 3 + Na 2 CO 3  Al 2 (CO 3 ) 3 + NaCl Double Replacement

8. CS 2 + O 2  CO 2 + SO 2 Single Replacement

9. Cr + O 2  CrO 3 Synthesis Reaction