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{{Element | name=Oxygen | symbol=O | anumber=8 | amass=15.994 amu | state=gas | class=Non-metal | cstructure=Cubic | color=Colorless | date=1774 | discname=[[Joseph Priestley]] | origname=From the Greek words ''oxus'' (acid) and ''gennan'' (generate) | uses=Supports life | obtained=From liquid air}}

{{Element | name=Oxygen | symbol=O | anumber=8 | amass=15.994 amu | state=gas | class=Non-metal | cstructure=Cubic | color=Colorless | date=1774 | discname=[[Joseph Priestley]] | origname=From the Greek words ''oxus'' (acid) and ''gennan'' (generate) | uses=Supports life | obtained=From liquid air}}

Oxygen is the third most abundant element in the universe by mass and is essential to life on Earth.

'''Oxygen''' is the third most abundant element in the universe by mass and is essential to life on Earth.

==Chemical Properties==

==Chemical Properties==

==Isotopes==

==Isotopes==

There are three stable and 14 radioactive isotopes of oxygen. The stable isotopes are ¹⁶O, ¹⁷O and ¹⁸O, with ¹⁶O being by far the most common. Radioisotopes range from ¹⁰O to ²⁶O, with the two most stable being ¹⁵O and ¹⁴O. This gives oxygen an atomic weight of slightly below 16. <ref>http://education.jlab.org/itselemental/iso008.html</ref>

There are three stable and 14 radioactive isotopes of oxygen. The stable isotopes are ¹⁶O, ¹⁷O and ¹⁸O, with ¹⁶O being by far the most common. Radioisotopes range from ¹⁰O to ²⁶O, with the two most stable being ¹⁵O and ¹⁴O. This gives oxygen an atomic weight of slightly below 16.<ref>http://education.jlab.org/itselemental/iso008.html</ref>

==Compounds==

==Compounds==

Oxygen is highly reactive. It reacts readily with most metals and many other elements, either through combustion or oxidation. As a result many naturally occurring compounds contain oxygen.

Oxygen is highly reactive. It reacts readily with most metals and many other elements, either through combustion or oxidation. As a result, many naturally occurring compounds contain oxygen.

==Occurrence in Nature==

==Occurrence in Nature==

Oxygen is the third most abundant element in the universe by mass after [[hydrogen]] and [[helium]]; approximately 5.9% of the mass of our [[solar system]] consists of oxygen. However due to the large disparity in atomic weight between all isotopes of oxygen compared with ¹H and ⁴He, less than 0.5% of the atoms in the solar system are oxygen atoms.{{fact}}

Oxygen is the third most abundant element in the universe by mass after [[hydrogen]] and [[helium]]; approximately 5.9% of the mass of our [[solar system]] consists of oxygen. However, due to the large disparity in atomic weight between all isotopes of oxygen compared with ¹H and ⁴He, less than 0.5% of the atoms in the solar system are oxygen atoms.{{fact}}

Due to its reactivity free oxygen is extremely rare in nature and would not exist on Earth without the process of [[photosynthesis]]. Geologists and paleontologists believe that free oxygen first appeared during the "Great Oxygenation Event" around 2.4 billion years ago. Young-Earth creationists reject this timescale.

Due to its reactivity free oxygen is extremely rare in nature and would not exist on Earth without the process of [[photosynthesis]]. Geologists and paleontologists believe that free oxygen first appeared during the "Great Oxygenation Event" around 2.4 billion years ago. Young-Earth creationists reject this timescale.

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{{Periodic table}}

 

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