[Discovery of Oxygen]
Oxygen was discovered almost simultaneously by several scientists in the late 18th century. Swedish pharmacist Carl Wilhelm Scheele first isolated oxygen in 1772, but his findings were published later. British scientist Joseph Priestley independently discovered oxygen in 1774 and called it "dephlogisticated air." French chemist Antoine Lavoisier used these discoveries to argue that oxygen plays a crucial role in compounds, laying the groundwork for modern chemistry. Scheele and Priestley did not recognize that oxygen is essential for combustion and respiration. However, Lavoisier analyzed this gas through experiments and named it "oxygen," meaning "acid producer." He also demonstrated the law of conservation of mass, showing that matter is neither created nor destroyed in chemical reactions. Lavoisier's research sparked a chemical revolution, forming an important foundation for the development of modern chemistry and biology. Today, oxygen constitutes about 21% of the air we breathe and is widely used for life support and industrial purposes.