1. Chemical Reactions

2. Cornell Notes  Title your notes: Chemical Reactions Notes  Add topics and summary after re-reading the notes.

3. Metabolism  An incredibly large number of chemical reactions happen in your body every second of your life.  Metabolism is a term used to describe all of the chemical reactions in a person’s body.

4. Reactants and Products  In chemical reactions, molecules are changed in some way. The beginning molecule(s) are the reactants and the resulting molecule(s) are the products. R E A C T A N T S P R O D U C T S

5.  This is an example of a chemical reaction: H 2 O 2  H 2 O + O 2 Hydrogen is broken down Water and Oxygen Peroxide in your cells into R E A C T A N T S P R O D U C T S

6.  Hydrogen peroxide is made in your cells all the time. However, it is toxic if it is not quickly broken down into water and oxygen, which are not toxic.

7.  Chemical reactions don’t happen spontaneously though. Every chemical reaction requires a certain amount of energy in order for it to happen.

8.  For a chemical reaction to take place, it has to “get over the hump,” as far as energy is concerned.

9.  The amount of energy a chemical reaction requires is called its activation energy. A chemical reaction will not occur until it has this amount of energy. The activation energy corresponds to the top of the “hump” on the graph.

10.  Label graph

11.  The activation energy of most chemical reactions is too high for them to happen on their own. Luckily your body has enzymes to help.

12.  Enzymes are proteins your body has that work by binding to a specific molecule and lowering its activation energy. The graph below represents the chemical reaction from above with an enzyme lowering its activation energy:

13.  The “hump,” or activation energy, has been lowered so not as much energy is required for it to occur.

14.  For example, your body has an enzyme called catalase that helps the cells break down hydrogen peroxide so it doesn’t poison you. CATALASE  +

15.  When the activation energy is lowered, the chemical reaction happens much faster. Another word for an enzyme is a catalyst.

16.  A catalyst speeds something up (enzymes speed up chemical reactions ).