Oxygen
Oxygen gas () was isolated by Michael Sendivogius before 1604. It is often thought that the gas was discovered in 1773 by Carl Wilhelm Scheele, in Sweden, or in 1774 by Joseph Priestley, in England. Priestley is usually thought to be the main discoverer because his work was published first (although he called it "dephlogisticated air", and did not think it was a chemical element). Antoine Lavoisier gave the name oxygène to the gas in 1777. He was the first person to say it was a chemical element. He was also right about how it helps combustion work.