Oxygen was officially discovered in 1774, but had been discovered by several chemists without realizing it was a distinct element. Joseph Priestly is usually given credit for the discovery of oxygen, however it has been said that Carl Wilhelm Scheele had also independently discovered the element. Both chemists were able to produce oxygen by heating mercuric oxide (HgO). Priestly and Scheele both had separate names for the element, however, the name oxygen was created by Antoine Lavoisier. The behaviour of oxygen and nitrogen as the components of air led to the advancement of the theory of combustion. This advancement influenced chemists for a century or so, as well as delaying an understanding of air for many years.
Oxygen is the first element in Group 16 of the periodic table, known as the chalcogen family. Coming from the Greek word chalkos, chalcogen means "ore". Oxygen and sulfur, the first two elements of the chalcogen family are found in most ores.
Joseph Priestly
Joseph Priestly was an English Unitarian minister and chemist. In his younger years, he was a great student. With help from local teachers, Joseph became very skilled in physics, philosophy, algebra, mathematics, and several different languages. Along with Joseph's scientific discoveries (such as Oxygen) and advancements, he wrote many books throughout his lifetime.
Carl Wilhelm Scheele
Carl Wilhelm Scheele is said to be one of the most important chemists of the 18th century. From a young age he had shown an interest in pharmacy and chemistry. Carl became a member of the Swedish Academy of Science in Stockholm where he discovered various chemical elements and compounds. He was also the first to discover the absorption of gases by charcoal, as well as his most famous (shared) discover of oxygen in the air.