• Chemical reactions either require energy or release energy.
  • The amount of energy needed or released depends upon the structure of the molecules that are involved in the reaction.
  • Some reactions need to be heated for long periods of time in order for change to take place.
  • Other reactions release energy, allowing heat to be given off to the surroundings.
  • Energy can be used in a variety of ways, including fuel for cars, trucks, airplanes, trains, and other vehicles.
  • The general principle behind these reactions is the release of electrons that can then flow through a circuit.
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