Chemical reactions and energy

• An exothermic reaction produces heat.
• An endothermic reaction absorbs heat.
• Activation energy is the minimum energy required to start a chemical reaction.
• During a chemical reaction, energy is required to break bonds, and energy is produced to make new bonds.
• The total energy of a chemical reaction:

  energy breaking bonds-energy making bonds.
• If the total energy of a reaction is positve, it is endothermic as it is taking in energy.
• If the total energy of a reaction is negative, it is exothermic as it is releasing energy as heat.