What type of reaction occurs when bonds are formed, resulting in the release of energy?

A reaction in which bonds are formed and energy is released is classified as an exothermic reaction. When chemical bonds are created, the system typically releases energy, often in the form of heat, to the surroundings. This release of energy is a hallmark of exothermic processes.

In a broader context, during exothermic reactions, the total energy of the products is lower than the total energy of the reactants because energy is released when new bonds are formed. Common examples of exothermic reactions include combustion reactions (like burning fuels) and certain condensation processes.

Other types of reactions, like endothermic reactions, absorb energy instead of releasing it. Reversible reactions can go both ways, meaning they can absorb or release energy depending on the direction, while catalytic reactions involve the presence of a catalyst to lower the activation energy, but they do not inherently involve the release of energy in the bond formation process.