What did antoine lavoisier contribute to the atomic theory

Antoine lavoisier is most famous for his role in discovering of oxygen. He recognized and name two important element oxygen (1778) and hydrogen (1779).

In a chemical reaction, Lavoisier observed the mass is retained. A chemical reaction's total mass of the products will always be the same as the total mass of the reactant materials used in the reaction. His results led to one of the basic laws of chemical behavior: the law of material preservation, which states that matter is preserved in a chemical reaction.