who discovered oxygen

Oxygen was discovered about 1772 by the Swedish chemist Carl Wilhelm Scheele, who obtained it by heating potassium nitrate and mercuric oxide. Independently, the English chemist Joseph Priestley discovered oxygen in 1774 by the thermal decomposition of mercuric oxide and published his findings that same year. While Scheele was the first to isolate oxygen, his publication came after Priestley's. The French chemist Antoine Lavoisier later conducted further investigations, recognized oxygen as an element, explained its role in combustion and respiration, and gave it the name "oxygen" from the Greek meaning "acid former".