December 8, 2014 Objective: ▫To understand what elements combine to form what compounds ▫Describe how chemical reactions work Journal: ▫Have you ever done a chemical reaction? Describe what you did.

Chemical Reactions

Chemical Makeup of Compounds Written as atomic symbols with subscripts ▫Atomic symbols tell what elements are in the compound ▫Subscripts tell how many of each element are in the compound ▫Examples:  H 2 O  C 6 H 12 O 6

Chemical Reaction The process of rearranging the bonds within two or more substances in order to form at least one new substance

Reactants A substance that is present at the beginning of a chemical reaction

Products A substance that is formed during a chemical reaction

Which side are reactants and which side are products? 6CO 2 +6H 2 0  C 6 H 12 O 6 + 6O 2

The number before the compound tells you how many of each compound are on each side of the reaction Must have an equal number of each element on both sides of the reaction because matter cannot be created or destroyed

Chemical Reactions will only occur under certain conditions… It must have enough energy. The atoms must be aligned properly.

Activation Energy The amount of energy required to start a chemical reaction

Enzymes function to speed up the reaction by lowering the activation energy. Not as much energy is needed for the reaction to occur when enzymes are present. Often activation energies are very high so….

Conditions: Enzymes are proteins which only work under certain temperatures and levels of pH, so if pH or temperature changes too much the enzymes won’t work properly

Enzymes are important to life. Without enzymes reactions would not occur quickly enough for organisms to survive.