Oxygen is the second most plentiful element on Earth, making up 46% of the Earth’s crust. Air is 20.94% oxygen.
Oxygen is one of the most reactive elements. This is why oxygen in the Earth’s crust is usually found joined with other chemicals in compounds.
Oxygen has an atomic number of 8 and an atomic weight of 15.9994.
Oxygen molecules in the air are made from two oxygen atoms; three oxygen atoms make the gas ozone.
Oxygen turns to a pale blue liquid at —182.962°C. It freezes at —218.4°C.
Most life depends on oxygen because it joins with other chemicals in living cells to give the energy needed for life processes. The process of using oxygen in living cells is called cellular respiration.
Liquid oxygen, or LOX, is combined with fuels such as kerosene to provide rocket fuel.
Oxygen was discovered independently by Carl Scheele and Joseph Priestley during the 1770s.
The name ‘oxygen’ means acid-forming. It was given to the gas in 1779 by Antoine Lavoisier.