Chemistry Regents Practice Test 2026 – Complete Prep Resource

When a chemical bond is broken, it typically requires an input of energy to overcome the forces that hold the atoms together. This energy requirement is characteristic of an endothermic reaction, which is defined as a process that absorbs energy, usually in the form of heat, from the surroundings. Consequently, breaking bonds involves energy intake, making the reaction endothermic.

In contrast, exothermic reactions release energy when new bonds are formed, generally resulting in a temperature increase in the surrounding environment. While redox and combustion reactions involve various energy changes and transformations, they are not specifically defined by the breaking of chemical bonds alone. Redox reactions involve electron transfer between species, and combustion involves the rapid combination of a substance with oxygen, usually producing heat and light.

Thus, the process of breaking chemical bonds is aligned with endothermic reactions, as it necessitates energy absorption to proceed.