Reactant substances are the starting materials in a chemical reaction. They are the substances that transform during the reaction to form new substances called products.

Think of it like baking a cake:

* Reactants: Flour, sugar, eggs, butter, milk

* Reaction: Mixing and baking

* Products: A delicious cake

Here's a more technical definition:

Reactants are chemical species that undergo a chemical change in a chemical reaction. They are typically represented on the left side of a chemical equation, separated by plus signs.

For example:

In the reaction of hydrogen and oxygen to form water:

2H₂ + O₂ → 2H₂O

* Reactants: Hydrogen (H₂) and Oxygen (O₂)

* Products: Water (H₂O)

Key points about reactants:

* They are the ingredients of a chemical reaction.

* They combine to form products.

* Their bonds are broken and reformed during the reaction.

* They disappear or change in form as the reaction progresses.