2.  A chemical change changes the nature and characteristic properties of matter.

3.  A chemical change is often called a chemical reaction because one of more substances called reagents, react to make new substances called products.  Bonds are broken and rearranged.  The products have different characteristic properties than the reagents.  During a chemical change, the number of atoms stays constant.

4.  Nothing is lost or created, all is transformed.  The total mass of the reagents is always equal to the total mass of the products.

5.  1) the release of a gas ◦ NaHCO 3 (aq) + CH 3 COOH (aq) ----> CO 2 (g) + H 2 O (l) + CH 3 COONa (aq)  2)change of colour ◦ 2 Cu(s ) + O 2 (g ) --> 2 CuO(s )  3) generation of heat ◦ CH 4 + 2 O 2 → CO 2 + 2 H 2 O + energy  4)formation of a precipitate ◦ 2KI(l)+Pb(NO3)2 (l)-->PbI2 (p)+ 2KNO3 (l) 5) generation of light

6.  Definition: The formation of a complex molecule from atoms or simpler molecules  Synthesis can either release energy or absorb it.  Ex: 2H₂ + O₂ > 2H₂O + energy  Reagents: 2H₂ + O₂ (4H, 2O)  Products: 2H₂O (4 H, 2O)  Note: This reaction produces enough energy to power a rocket engine.

7.  In living things, synthesis always absorbs energy, which is transformed into chemical energy and stored in the bonds of molecules.  Examples: formation of fats, carbohydrates, proteins, DNA, ATP.

8.  Write the chemical reaction for photosynthesis  6 CO₂ + 6H₂O + solar energy> C₆H₁₂O₆ +6O₂  Where is the solar energy stored?  Reagents: 6 CO₂ + 6H₂O (6 C, 18 O, 12H)  Products: C₆H₁₂O₆ +6O₂ (6 C, 18O, 12H)  Therefore, this equation is balanced, it obeys the law of conservation of matter.

9.  Definition: The transformation of complex molecules into simpler molecule or into atoms.  The chemical energy stored in the molecule is usually released and transformed into other forms of energy.  When we need energy, our cells decompose glycogen into glucose, or decompose glucose into carbon dioxide and water, which releases energy.  What is the decomposition of glucose called?

10.  C₆H₁₂O₆ + 6O₂ > 6 CO₂ + 6H₂O + ATP (chemical energy )  Where does the chemical energy come from?  Less energy is required to break the bonds of glucose and oxygen than to remake the bonds of carbon dioxide and water so energy is released.

11.  More energy is required to reorganize the bonds of the molecule than the bonds contain so energy must be absorbed.  Ex: The electrolysis of water  The quantity of energy produced by the decomposition of a molecule is the same as is required for its synthesis.

12.  Definition: A chemical reaction involving oxygen or a substance that has similar properties to oxygen (sulpher, floride, chlorine).  Can be thought of as a type of synthesis> a substance combines with oxygen.  Usually involves a release of energy.

13. ◦ Usually involves a release of energy. 1)Cellular respiration: glucose combines with oxygen and energy is released that is used by our bodies to move, stay warm (metabolism), build cells,etc. 2)Combustion: wood combines with oxygen to release thermal or radiant energy. 3)Rusting of metals. This leads to the corrosion (deterioration) of the metal. The energy released is difficult to notice because it takes a long time for this process to take place.

14.  The formation of a solid that is less soluble, or not soluble, following the mixing of 2 solutions.  Precipitation requires very little energy  Example: vinegar and milk produces a precipitate because the vinegar reacts with a protein in milk.