What processes are involved in endothermic and exothermic reactions?

formation of snow in clouds conversion of frost to water vapor
condensation of rain from water vapor evaporation of water
a candle flame forming a cation from an atom in the gas phase
mixing sodium sulfite and bleach baking bread
rusting iron cooking an egg
burning sugar producing sugar by photosynthesis
forming ion pairs separating ion pairs
Combining atoms to make a molecule in the gas phase splitting a gas molecule apart

Those are some examples