Oxygen, which is a gaseous element, tasteless and colorless, is distributed throughout nature. Forms about half the Earth is in the air, which contains 21% of this gas essential to living things in the water (consisting of 88.8% oxygen), and rocks, also found in all living tissues and in many substances. Oxygen can be obtained artificially in the laboratory from certain salts such as barium peroxide, sodium peroxide and potassium chlorate. Among the procedures used for production are the fractional distillation of liquid air and water electrolysis. Can be stored in gaseous or liquid. The oxygen thus obtained has many uses: in medicine it provides to patients with respiratory problems, in addition, they use people who fly at high altitudes, and is also used for soldering at high temperatures.
Oxygen was discovered by English chemist Joseph Priestley in 1774. Later, Antoine Laurent Lavoisier French research Priestley deepened and proved that there is always air oxygen, which acts as an agent and is the cause of combustion, oxidation of metals and respiration of living beings.
The oxygen is represented by the letter O. The atomic weight is 16, its atomic number 8, the melting point, -218 ° C and the boiling point, -183 ° C.
Animals breathe in oxygen and exhale carbon dioxide.
During the day the plants absorb carbon dioxide and give off oxygen.
At night, plants emit only carbon dioxide.