Energy level diagrams

• Energy Level Diagrams

  Diagrams that show the energy stored in reactants and products of a chemical reaction
• Components of a chemical reaction

  • Molecules
  • Atoms
  • Bonds
  • Products
• Atoms are held together by bonds
• During a chemical reaction, bonds between the reactants are broken. New bonds are then formed to make the products
• Energy is needed to break bonds and this is taken in from the surroundings
• Energy is released when new bonds are formed and this is transferred to the surroundings
• Exothermic reaction

  A reaction where the energy needed to break bonds is less than the energy released when new bonds are made
• Endothermic reaction

  A reaction where the energy needed to break bonds is greater than the energy released when new bonds are made
• Energy level diagram

  1. Horizontal lines show the energy stored in reactants and products

  2. Horizontal axis represents the progress of the reaction from reactants to products
• Exothermic reaction

  • Methane burning in oxygen to form carbon dioxide and water
• Endothermic reaction

  • Nitrogen reacting with oxygen to form nitrogen monoxide