Bond Energies

What is Bond Energies?

Within Chemistry, which covers atoms, bonding, reactions, the periodic table, organic chemistry and the chemistry of everyday life, this topic explains Bond Energies. Chemistry links what you can see in the lab to the particles and bonds behind it, so each topic here shows that link in a model.

Check that you can explain Bond Energies in your own words and give one example from everyday life. If you can do that, you have understood the core idea.

Understanding Bond Energies helps you explain why substances behave as they do, from cleaning products and food to medicines.

Bond Energies in detail

Bond energy is the energy required to break one mole of a particular covalent bond, measured in kJ/mol. Breaking bonds takes in energy (endothermic) and making bonds releases energy (exothermic).

The overall energy change = energy needed to break bonds in reactants − energy released making bonds in products. If more energy is released than is taken in, the reaction is exothermic. This calculation explains why fuels release energy when they burn, such as the strong C=O and O–H bonds forming in carbon dioxide and water.

How the interactive helps you understand Bond Energies

Watch the bonding model in the interactive. Use any sliders or buttons it offers to change the values and see how the bonding model responds.

Before you change anything, predict the result. Then change one value at a time and check whether your prediction was right. This is a quick way to build a correct mental model of Bond Energies.

Real-life uses and examples

• Use Bond Energies to explain what happens in a lab experiment and why.
• Link Bond Energies to everyday products such as cleaning agents, food and medicines.
• Read a chemical equation or diagram and work out what Bond Energies shows.

Common mistakes to avoid

• Describing what happens without explaining the particles or bonds involved.
• Mixing up the names of substances or ions when you describe Bond Energies.
• Learning the definition without testing it. Use the quiz and the interactive to check that you can apply the idea.