In a chemical reaction, a chemical reactant is a substance that undergoes a chemical change during the reaction. Think of them as the ingredients in a recipe.

Here's a breakdown:

* Reactants are the starting materials of a chemical reaction.

* They are present before the reaction takes place.

* They combine and interact with each other to form new substances.

* These new substances are called products.

Example:

In the reaction of burning methane (CH₄) with oxygen (O₂):

CH₄ + 2O₂ → CO₂ + 2H₂O

* Reactants: Methane (CH₄) and Oxygen (O₂)

* Products: Carbon dioxide (CO₂) and water (H₂O)

Key points:

* Reactants are usually written on the left side of a chemical equation.

* Products are usually written on the right side of a chemical equation.

* The arrow (→) indicates the direction of the reaction, from reactants to products.

Let me know if you'd like more examples or a deeper explanation!