Editing Oxygen

[[File:Antoine lavoisier.jpg|Antoine Lavoisier|thumb]]
[[File:Goddard and Rocket.jpg|Goddard and Rocket|thumb]]
[[File:A setup for preparation of Oxygen.jpg|A setup for preparation of Oxygen|thumb]]
[[File:Oxygen molecule orbitals diagram-en.svg|Oxygen molecule orbitals diagram|thumb]]
[[File:Liquid oxygen in a magnet 2.jpg|Liquid oxygen in a magnet|thumb]]
{{Short description|Chemical element with symbol O and atomic number 8}}

'''Oxygen''' is a [[chemical element]] with the [[symbol (chemistry)|symbol]] '''O''' and [[atomic number]] '''8'''. It is a member of the [[chalcogen]] group on the [[periodic table]], and is classified as a highly reactive [[nonmetal]] and a strong [[oxidizing agent]]. Oxygen readily forms [[oxides]] with most elements and many compounds.

== Properties ==
* Atomic number: 8
* Symbol: O
* Atomic mass: 15.999 u
* Electron configuration: 1s² 2s² 2p⁴
* Standard state: Gas at room temperature
* Appearance: Colorless, odorless gas

Oxygen exists in several allotropes, the most common of which is diatomic oxygen (O₂), essential for [[cellular respiration]] in most [[aerobic organisms]]. Another allotrope, [[ozone]] (O₃), plays a critical role in absorbing ultraviolet radiation in the Earth's [[stratosphere]].

== Abundance and Occurrence ==
Oxygen is:
* The most abundant element in the [[Earth's crust]] by mass
* The second-most abundant component of the [[Earth's atmosphere]] (approximately 21%)
* The third-most abundant element in the [[universe]], after [[hydrogen]] and [[helium]]

It is found in water (H₂O), [[silicates]], [[oxides]], and in all known life forms.

== Biological Role ==
Oxygen is essential for life in many forms:
* Required for [[aerobic respiration]] in plants, animals, fungi, and most [[bacteria]]
* Produced as a byproduct of [[photosynthesis]] in [[plants]], [[algae]], and [[cyanobacteria]]

Oxygen is transported in the bloodstream of vertebrates by the protein [[hemoglobin]].

== Industrial and Medical Uses ==
Oxygen has a wide array of applications, including:
* [[Medical oxygen]] therapy and life support systems
* [[Oxy-fuel welding]] and cutting
* Steel and chemical manufacturing
* Water treatment and environmental monitoring
* Rocket propellants and high-altitude breathing equipment

== History ==
Oxygen was independently discovered in the 1770s by:
* [[Carl Wilhelm Scheele]] in Sweden (before 1773)
* [[Joseph Priestley]] in England (1774)

The name "oxygen" was coined by [[Antoine Lavoisier]], who helped establish its role in combustion and respiration, disproving the phlogiston theory.

== Gallery ==
== Oxygen ==
<gallery>
File:PriestleyFuseli.jpg|Priestley and Fuseli
File:Oxygen molecule.png|Oxygen molecule
File:Liquid oxygen in a beaker 4.jpg|Liquid oxygen in a beaker
File:Evolved star fusion shells.svg|Evolved star fusion shells
File:WOA09 sea-surf O2 AYool.png|Sea surface oxygen
File:Phanerozoic Climate Change.png|Phanerozoic Climate Change
File:Simple photosynthesis overview.svg|Simple photosynthesis overview
</gallery>

== See Also ==
* [[Periodic table]]
* [[Photosynthesis]]
* [[Respiration]]
* [[Ozone layer]]
{{stub}}
[[Category:Oxygen]]
[[Category:Chemical elements]]
[[Category:Oxidizing agents]]
[[Category:Chalcogens]]
[[Category:Life sciences]]