1. Exothermic and Endothermic Reactions
It’s a give and take relationship!!!!

2. Every Reaction Involves Energy
During a reaction…bonds
absorb energy and break
2. New bonds form…energy
released
STEPS

3. Symbols In Chemical Reactions
= Solid Formation
= Gas Formation

4. Symbols In Chemical Reactions
Heat
Heat is given off
Light Energy
Energy
Electrical Energy
Thermal Energy

5. What Is A Chemical Reaction?
Chemical Reaction: the process by which one or more substances undergo change to produce one or more different substances
How To Identify A Chemical Reaction Has Occurred Or Is Happening
1. Gas Formation
2. Solid Formation
3. Color Change
4. Energy Change

6. Parts To A Chemical Reaction
Reactants: starting materials of a
chemical reaction
2.Products: substances formed
Products
Reactants C O2
CO2

7. What Do You Notice About All The Atoms?
Chemical Reaction 2
Products
2Na
Cl2
2NaCl
Reactants
***
What Do You Notice About All The Atoms?

8. Energy is in the products in an Exothermic Reaction
Exothermic Reactions
Chemical Reaction in which energy is released or removed
2 Na + Cl2  2 NaCl + Energy
Energy is in the products in an Exothermic Reaction

9. Endothermic Reactions
Chemical reaction in which energy is absorbed
6 CO2 + 6 H2O + Energy  C6H12O
Energy is in the reactants in an Endothermic Reaction

10. Chemical Reactions Must Be Balanced!!!!
It’s a Law!!!!!!!!!!!
The Law Of Conservation Of Mass
**Mass is neither created nor destroyed in ordinary chemical reactions