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Oxygen Oxygen is the most abundant element on the earth. It makes up 23 percent of air, 89 percent of water, and about 46 percent of crustal rock It also comprises 60 percent of the human body. Oxygen is an essential element for survival. Without it, we would not be here today. In this report, you will learn how oxygen, in its many forms, is very important. Oxygen was first discovered in 1774 by the British chemist Joseph Priestley, when he decomposed mercury II oxide into its elements by heating it. Karl Wilhelm Scheel, a Swedish chemist, discovered it when he heated manganese dioxide with concentrated sulfuric acid.. French chemist, Antoine Laurent Lavoisier, proved it was an elemental gas, through his experiments on combustion. He also gave oxygen its name. In 1929, W.F. Giaque and H.L. Johnston announced the discovery of two isotopes of oxygen, with mass numbers of 17 and 18. Oxygen is a colorless, odorless, tasteless gas, located in group VIa of the periodic table. It is slightly denser than air. It is a poor conductor of heat and electricity, and slightly soluble in water. Oxygen also supports combustion, but does not burn. Its atomic number is 8. Its atomic mass is 15.9994. Oxygen melts at -218.4 C and boils at -183 C. It contains 8 protons, electrons, and neurtons. It is also classified as a nonmetal, which has 2 energy levels. It is also slightly magnetic and not harmful at all. Oxygen can be condensed to a pale blue liquid, which is very magnetic. It is produced by compressing the liquid. Oxygen used to be the official standard for the atomic weights of elements. The chemists used natural oxygen, to which the value of 16 was assigned. In 1961, however, carbon-12 replaced oxygen as the standard. There are only three allotropic forms of oxygen known today. There is ordinary oxygen, which contains two atoms per molecule. Its formula is O2. Ordinary oxygen is relatively reactive and combines with most elements to form oxides. O2 is required for us to breathe. Ozone, on the other hand, contains three atoms per molecule. Its formula is O3. Ozone is formed when oxygen in the air is subjected to an electrical discharge, such

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