The birth of the modern atomic theory. In 1750, Rudjer Boscovich, a scientist born in what is now Croatia, suggested the theory that atoms were "uncuttable" might have been wrong. Boscovich thought that atoms contain smaller parts, which in turn contain still smaller parts, and so forth down to the fundamental building blocks of matter. He felt that these building blocks must be geometric points with no size at all. Today, most atomic physicists accept a modern form of this idea.
Antoine Lavoisier, a French chemist, revolutionized chemistry in the late 1700's. He repeated many of the experiments of earlier chemists but interpreted the results far differently. Lavoisier paid particular attention to the weight of the ingredients involved in chemical reactions and of the products that resulted. He found that the weight of the products of combustion equals that of the original ingredients. His discovery became known as the law of the conservation of matter.
Lavoisier noted that the weight of the air in which combustion occurred decreases. He found that the weight loss results from the burning material combining with and removing a substance in the air. That substance was the same as dephlogisticated air, but Lavoisier renamed it oxygen.
Lavoisier and Pierre Simon Laplace, a French astronomer and mathematician, also carried out experiments demonstrating that respiration in animals is chemically similar to combustion. Their studies of the chemical processes of living organisms were among the first experiments in biochemistry. Lavoisier also helped work out the present-day system of chemical names. He published his ideas on combustion, respiration, and the naming of compounds in Elementary Treatise on Chemistry (1789), the first modern textbook of chemistry.
The development of the atomic theory advanced greatly when chemistry became an exact science during the late 1700's. Chemists discovered that they could combine elements