1. Kinetic Energy Topic 3 Units 4 & 5

2. Elements form bonds to become more stable. A filled valence configuration is very stable. This is why noble gases (group 18) are stable and do not react. When elements react to form compounds they exchange or share the correct number of electrons to reach this stable state.

3. Potential energy is stored energy. Chemical bonds contain potential energy.

4. Energy is required to break bonds. –Breaking bonds is endothermic (requires energy). Energy is released when bonds are formed. – Forming bonds is exothermic (energy is released).

5. Chemical reactions are either endothermic or exothermic depending on whether the total energy needed to break the old bonds or the energy released when forming the new bonds is greater.

6. In chemical reactions bonds are broken and new bonds are formed. The energy absorbed in breaking the bonds is never exactly equal to the energy released when the new bonds are formed. Therefore, all reactions are accompanied by a change in potential energy that can be measured and is represented by the symbol  H.

7. An energy level diagram can also be used to represent the energy change during a chemical reaction.

8. Reactants Products ∆H Positive or negative change? + Time Energy Is Energy being gained (absorbed) or lost (released)? Energy is gained (absorbed) Endothermic or Exothermic? ENDOTHERMIC

9. Reactants Products ∆H Positive or negative change? - Time Energy Is Energy being gained (absorbed) or lost (released)? Energy is lost (released) Endothermic or Exothermic? EXOTHERMIC

10. Gummy Bear Pre Lab Questions Write the balanced equation for the decomposition reaction of potassium chlorate (KClO 3 ) forming potassium chloride and oxygen gas. How many grams of potassium chloride will be produced from the decomposition of 5.0 grams of KClO 3 ?

11. Gummy Bear Conclusion Was energy released or absorbed? Was it an endothermic or exothermic reaction? The gummy bear was used as a catalyst in the reaction. How did it affect the activation energy? Draw the energy level diagram you witnessed during the reaction.