| 1. Oxygen (1770s) Joseph Priestley discovers oxygen; later, Antoine Lavoisier clarifies the nature of elements. Priestley produces oxygen in experiments and describes its role in combustion and respiration. Then, by dissolving fixed air in water, he invents carbonated water. Priestley, oblivious to the importance of his discovery, calls the new gas "dephlogisticated air." Lavoisier gives oxygen its name and correctly describes its role in combustion. Lavoisier then works with others to devise a chemical nomenclature, which serves as the basis of the modern system. 2. Atomic Theory (1808) John Dalton provides a way of linking invisible atoms to measurable quantities like the volume of a gas or mass of a mineral. His atomic theory states that elements consist of tiny particles called atoms. Thus, a pure element consists of identical atoms, all with the same mass, and compounds consist of atoms of different elements combined together. 3. Atoms Combine Into Molecules (1811 onward) Italian chemist Amedeo Avogadro finds that the atoms in elements combine to form molecules. Avogadro proposes that equal volumes of gases under equal conditions of temperature and pressure contain equal numbers of molecules. 4. Synthesis of Urea (1828) Friedrich Woehler accidentally synthesizes urea from inorganic materials, proving that substances made by living things can be reproduced with nonliving substances. Until 1828, it was believed that organic substances could only form with the help of ... |
