Oxygen
Oxygen is a chemical element with the 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[edit]
- 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[edit]
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[edit]
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[edit]
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[edit]
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[edit]
Oxygen[edit]
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Priestley and Fuseli
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Oxygen molecule
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Liquid oxygen in a beaker
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Evolved star fusion shells
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Sea surface oxygen
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Phanerozoic Climate Change
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Simple photosynthesis overview
See Also[edit]
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