Stoichiometry is a branch of chemistry that deals with the calculation of reactants and products in chemical reactions. It uses balanced chemical equations to determine the proportions of elements and compounds involved. By understanding these relationships, chemists can predict how much of each substance is needed or produced in a reaction. In stoichiometry, the concept of the mole is essential, as it allows for the conversion between the mass of substances and the number of particles. This helps in quantifying the amounts of reactants and products, ensuring that reactions proceed efficiently and safely.