Reactants

Definition

Reactants are the starting substances in a chemical reaction that undergo change to form products. They are present on the left side of a chemical equation.

5 Must Know Facts For Your Next Test

1. Reactants participate directly in the chemical reaction and get consumed during the process.
2. In a balanced chemical equation, the number of atoms for each element in the reactants must equal the number of atoms for those elements in the products.
3. The physical state of reactants (solid, liquid, gas, or aqueous) is often indicated in parentheses next to their chemical formulas.
4. Stoichiometric coefficients represent the relative amounts of reactants needed for the reaction to proceed completely.
5. Limiting reactant is the reactant that gets completely consumed first, thereby limiting the amount of product formed.

Review Questions

• What role do reactants play in a chemical reaction?
• How can you identify reactants in a balanced chemical equation?
• Why is it important to balance the number of atoms for each element on both sides of a chemical equation?

Related terms

Products:

Substances formed as a result of a chemical reaction. They appear on the right side of a chemical equation.

Limiting Reactant:

The reactant that is entirely consumed first during a chemical reaction, thus limiting the amount of product that can be formed.

Stoichiometry:

\text{The calculation of reactants and products in chemical reactions based on balanced equations.}