Explain what occurs in a substance reaction

The substances that go into a chemical reaction are called the reactants, and the substances produced at the end of the reaction are known as the products.

Explanation:

Chemicals reaction bond between atoms are formed and broken

In a chemical reaction, the atoms of the starting species called reactants rearrange to form new substances which are the products of the chemical reaction. The identities of the atoms involved in the reaction remain the same. Their number also stays the same before and after the reaction