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History:
Oxygen is the third most abundant element in the universe,and it was relatively rare in early Earth's atmosphere.Oxygen was discovered about 1772 by a Swedish chemist, Carl Wilhelm Scheele, who obtained it by heating many substances (mercuric oxide, silver carbonate, magnesium nitrate, and other nitrate salts).

Isotopes:
three stable isotopes, 16O, 17O, and 18O, with 16O being the most abundant
16 (16O → 8 protons + 8 neutrons; a "light")
18 ( 18O → 8 protons + 10 neutrons; a "heavy").

Subatomic particles:
24 basic subatomic
8 protons ( positive charge)
8 electrons (negative charge)
8 neutrons. ( neutral charge)
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Relative atomic mass
The ratio of the average mass per atom of oxygen is 15.999
When protons and neutrons combine to form the oxygen nucleus, a very small amount of the total mass is converted to nuclear binding energy.