2. reactant + reactant products
Chemical Reactions
A chemical reaction is a reaction in which a chemical change occurs. Molecules are changed from one type to another.
Chemical reactions involve:
Reactants  the substances that exist before the reaction has occurred.
Products  the substances that exist after the reaction has occurred.
Chemical reactions are written in the following form:
reactant reactant products

3. A Simple Chemical Reaction+

4. Two Categories of Chemical Reactions
Chemical reactions either require or give off energy in the form of heat.
Exothermic  describes a chemical reaction in which energy is given off.
(exo = exit = leaves). The final product will feel warmer than the original reactants.
Endothermic  describes a chemical reaction in which energy is absorbed. The final product will feel cooler than the original reactants.
Endothermic
Reaction
Exothermic
Reaction

5. Indicators of Chemical Reactions
brand new colour
new odor
gas is created
precipitate forms
light is given off
change in temperature

6. Important Everyday Chemical Reactions
Digestion
Cooking