Chemical symbol: O

Available supply: 20.9 per cent of air; 50.5 per cent of the atmosphere, hydrosphere, biosphere and lithosphere combined.

Boiling point: -183 °C At atmospheric pressure, liquid oxygen takes up only one 854th of the volume it occupies as a gas

Freezing point: -219°C

Chemical properties: Reacts very readily, bonds with almost all other elements, participates in most combustion and corrosion processes.

O2

 More than half of the part of our planet which is accessible to humans – 50.5 per cent, to be exact – consists of oxygen. That’s the share of this element in the atmosphere, the hydrosphere (waters) and the Earth’s crust down to a depth of 16 kilometres. So based on its mass alone, this makes oxygen the most important foundation of our world.

The term “oxygen” is the result of a mistake in early natural science. The pioneers of chemistry in the 18th century thought that the colourless and odourless gas was responsible for the formation of acids. So they named it “oxygenium” (acid-forming agent), derived from the Greek word for acid: “oxys”.

Out in space, by the way, oxygen is the third most common element after hydrogen and helium, albeit in a far lower proportion than here on Earth. It makes up about 0.8 per cent of our solar system. Industrial operations take advantage of the reactive properties of oxygen in order to manufacture products as efficiently and cost-effectively as possible: oxygen is involved in most industrial processes in which combustion or chemical reactions play a role – from steelmaking to water treatment.

O2 Gas