Energy Changes
Energy changes must always accompany chemical reactions. You just learned how the law of conservation of energy demands that any energy released from a chemical reaction be equal to the energy gained by the surroundings and vice versa. Chemical reactions involve changes in energy because of the chemical bonds that hold atoms together. When a chemical reaction takes place, the bonds between atoms are rearranged. This involves breaking the chemical bonds in reactant molecules and forming new bonds in the product molecules. The two key points here are:
- Breaking chemical bonds requires energy and is therefore an endothermic process.
- Forming chemical bonds gives out energy and is therefore an exothermic process.
