(Gr. oxys, sharp, acid; and genes, forming) Priestley and Scheele discovered it independently. It is the third most abundant element found in the sun, plays a role in energy creation by the sun. Oxygen makes up 21% of the earth's atmosphere, 2/3 of the human body and nine tenths of water. Martian atmosphere contains about 0.15% oxygen. Ozone (three oxygens bonded together) is formed from electrical discharge or ultraviolet light acting on oxygen.
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Ozone in the atmosphere is protectin against the sun's ultraviolet rays,essential for respiration in animals and plants,enrichment of steel blast furnaces
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Highly reactive, combines with most elements,gas at room temp., eight isotopes, colorless