Oxygen

Oxygen was discovered in 1774 by Joseph Priestley. In 1777, Antoine Laurent de Lavoisier renamed "vital air" into "oxygen", from the Greek "-ὀξύς" (oxys), "acid" and "-γενής" (-genes), "producer", literally "begetter". Essential to life, it is the third most abundant element on the earth’s surface. Oxygen makes up (by weight) 46% of the Earth's crust (oxides, silicates, etc.), 89% of the Earth's water and 62 % of the human body (in the form of molecules). In its most well-known form, it constitutes 21 % of the atmosphere. Since oxygen is literally all around us, Oxygen is the most reactive of the non-metallic elements. As a gas, oxygen is clear. But as a liquid, it's pale blue.