Energy change

• Exothermic:

  Transfers thermal energy to its surroundings.
• Examples of exothermic reactions:

  • Combustion (fuels are burnt)
  • Oxidation
  • Neutralisation
• Endothermic:

  Take in heat energy from the surroundings.
• Activation energy:

  The minimum amount of energy needed for the reactants particles to collide with each other and react.
• Bond energy:

  Amount of energy needed to break one mole of a particular covalent bond.
• Breaking bonds is an endothermic reactions as it needs energy from its surroundings.
• Overall energy change = energy required to break bonds - energy realeased by forming bonds.