Reactants are the starting materials in a chemical reaction. They are the substances that undergo a chemical change and are consumed in the process.

Think of them like the ingredients in a recipe. Just like you combine flour, sugar, and eggs to make a cake, you combine reactants to create a new product.

Here's a simple example:

* Reaction: Burning wood

* Reactants: Wood and Oxygen

* Product: Ash, Carbon Dioxide, Water, and Heat

In this case, wood and oxygen are the reactants, and they react to produce ash, carbon dioxide, water, and heat.

It's important to note that:

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

* The chemical formula of each reactant is written with its corresponding coefficient to indicate the number of moles of that reactant involved in the reaction.

Let me know if you'd like to explore more about chemical reactions or have any other questions!