Energetics or thermochemistry (a branch of thermodynamics) is the study of the movement of heat energy (called enthalpy) in chemistry. Changes in enthalpy and entropy (a measure of the number of ways of arranging energy in a substance) can be used to accurately predict the outcome of chemical reactions.
Topic 5.3 Bond enthalpy values can be used to estimate enthalpy changes.
15.1 Born Haber cycles are used to calculate lattice enthalpies for ionic compounds.
Entropy and spontaneity
15.2 Entropy and Gibb's Free Energy allow us to predict if reactions are spontaneous (allowed).
Topic 5.2 Hess's Law allows us to measure enthalpy changes indirectly.
Measuring energy changes
Topic 5.1 Enthalpy is heat energy (at constant pressure) and we can measure enthalpy changes using ΔH=mcΔT.