Final answer:
In a chemical reaction, bonds within the reactant molecules break and rearrange to form new product molecules.
Step-by-step explanation:
In a chemical reaction, bonds within the reactant molecules are broken and rearranged to form new product molecules. The reactant molecules are made up of atoms held together by chemical bonds, and during a chemical reaction, these bonds break so that the atoms can rearrange and form new bonds in the product molecules.