Final answer:
In a chemical reaction, bonds in the reactants are broken and new bonds are formed in the products. Energy is required to break the bonds and is released when the bonds are formed. This rearrangement of atoms forms new substances.
Step-by-step explanation:
A chemical reaction involves breaking bonds in the reactants and forming new ones in the products. When a chemical bond is broken, energy is required, and when a chemical bond is formed, energy is released. The amount of energy needed to break a bond is the same amount of energy released when the bond is formed.
For example, in the reaction 2H₂O → 2H₂ + O2, the bonds of two water molecules (H₂O) are broken to form hydrogen (H₂) and oxygen (O2).
Overall, a chemical reaction involves the rearrangement of atoms and the breaking and forming of chemical bonds, which results in the creation of new substances with different compositions.