What is it
Students learn that chemical reactions can transfer energy to or from the surroundings, the difference between exothermic (energy released, gets warmer) and endothermic (energy absorbed, gets colder) reactions, with everyday examples like burning and cooking.
Why it matters
This is the first formal treatment of energy in chemical reactions, extended at GCSE into reaction profiles, bond energies and calculating energy changes numerically.
Exam tip
Link temperature change directly to energy direction — temperature rises for exothermic, falls for endothermic — this is the fastest way to identify reaction type in an exam question.
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