- Bond energy = energy needed to break 1 mole of a particular bond
- Units are kJ/mol (kilojoules per mole)
- Breaking bonds is ALWAYS endothermic (requires energy)
- Making bonds is ALWAYS exothermic (releases energy)
- If breaking > making: reaction is endothermic, ĪH positive
- If making > breaking: reaction is exothermic, ĪH negative
- Double bonds (C=C, O=O) have higher bond energy than single bonds
- Triple bonds (Nā”N) are even stronger
This key facts covers Key Facts: Bond Energies within Bond Energies (HT) for GCSE Chemistry. Revise Bond Energies (HT) in Energy Changes for GCSE Chemistry with 25 exam-style questions and 15 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 9 of 15 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
Practice questions for Bond Energies (HT)
Which statement correctly describes the energy change when chemical bonds are broken?
Explain how you would determine, from a bond energy calculation, whether a reaction is exothermic or endothermic.
Quick recall flashcards
What are the units for bond energy?
kJ/mol (kilojoules per mole)
What is bond energy?
The energy needed to break 1 mole of a particular bond