Oxygen (pronounced /ˈɒksɨdʒɨn/, OK-si-jin, from the Greek roots ὀξύς (oxys) (acid, literally "sharp", from the taste of acids) and -γενής (-genēs) (producer, literally begetter) is the element with atomic number 8 and represented by the symbol O. It is a member of the chalcogen group on the periodic table, and is a highly reactive nonmetallic period 2 element that readily forms compounds (notably oxides) with almost all other elements. At standard temperature and pressure two atoms of the element bind to form dioxygen, a colorless, odorless, tasteless diatomic gas with the formula O2. Oxygen is the third most abundant element in the universe by mass after hydrogen and helium[1] and the most abundant element by mass in the Earth's crust. Diatomic oxygen gas constitutes 20.9% of the volume of air.
All major classes of structural molecules in living organisms, such as proteins, carbohydrates, and fats, contain oxygen, as do the major inorganic compounds that comprise animal shells, teeth, and bone. Oxygen in the form of O2 is produced from water by cyanobacteria, algae and plants during photosynthesis and is used in cellular respiration for all complex life. Oxygen is toxic to obligately anaerobic organisms, which were the dominant form of early life on Earth until O2 began to accumulate in the atmosphere 2.5 billion years ago. Another form (allotrope) of oxygen, ozone (O3), helps protect the biosphere from ultraviolet radiation with the high-altitude ozone layer, but is a pollutant near the surface where it is a by-product of smog. At even higher low earth orbit altitudes atomic oxygen is a significant presence and a cause of erosion for spacecraft.
Oxygen was independently discovered by Carl Wilhelm Scheele, in Uppsala, in 1773 or earlier, and Joseph Priestley in Wiltshire, in 1774, but Priestley is often given priority because his publication came out in print first. The name oxygen was coined in 1777 by Antoine Lavoisier,[6] whose experiments with oxygen helped to discredit the then-popular phlogiston theory of combustion and corrosion. Oxygen is produced industrially by fractional distillation of liquefied air, use of zeolites to remove carbon dioxide and nitrogen from air, electrolysis of water and other means. Uses of oxygen include the production of steel, plastics and textiles; rocket propellant; oxygen therapy; and life support in aircraft, submarines, spaceflight and diving.
Contents
1 Characteristics
1.1 Structure
1.2 Allotropes
1.3 Physical properties
1.4 Isotopes and stellar origin
1.5 Occurrence
2 Biological role
2.1 Photosynthesis and respiration
2.2 Build-up in the atmosphere
3 History
3.1 Early experiments
3.2 Phlogiston theory
3.3 Discovery
3.4 Lavoisier's contribution
3.5 Later history
4 Industrial production
5 Applications
5.1 Medical
5.2 Life support and recreational use
5.3 Industrial
5.4 Scientific
6 Compounds
6.1 Oxides and other inorganic compounds
6.2 Organic compounds and biomolecules
7 Safety and Precautions
7.1 Toxicity
7.2 Combustion and other hazards
8 See also
9 Notes and citations
10 References
11 Further reading
12 External links
Photosynthesis and respiration
Photosynthesis splits water to liberate O2 and fixes CO2 into sugar
In nature, free oxygen is produced by the light-driven splitting of water during oxygenic photosynthesis. Green algae and cyanobacteria in marine environments provide about 70% of the free oxygen produced on earth and the rest is produced by terrestrial plants.[40]
A simplified overall formula for photosynthesis is:[41]
6 CO2 + 6 H2O + photons → C6H12O6 + 6 O2 (or simply carbon dioxide + water + sunlight → glucose + dioxygen)
Photolytic oxygen evolution occurs in the thylakoid membranes of photosynthetic organisms and requires the energy of four photons.[42] Many steps are involved, but the result is the formation of a proton gradient across the thylakoid membrane, which is used to synthesize ATP via photophosphorylation.[43] The O2 remaining after oxidation of the water molecule is released into the atmosphere.[44]
Molecular dioxygen, O2, is essential for cellular respiration in all aerobic organisms. Oxygen is used in mitochondria to help generate adenosine triphosphate (ATP) during oxidative phosphorylation. The reaction for aerobic respiration is essentially the reverse of photosynthesis and is simplified as:
C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + 2880 kJ·mol-1
In vertebrates, O2 is diffused through membranes in the lungs and into red blood cells. Hemoglobin binds O2, changing its color from bluish red to bright red.[19][45] Other animals use hemocyanin (molluscs and some arthropods) or hemerythrin (spiders and lobsters).[36] A liter of blood can dissolve 200 cm3 of O2.[36]
Reactive oxygen species, such as superoxide ion (O−2) and hydrogen peroxide (H2O2), are dangerous by-products of oxygen use in organisms.[36] Parts of the immune system of higher organisms, however, create peroxide, superoxide, and singlet oxygen to destroy invading microbes. Reactive oxygen species also play an important role in the hypersensitive response of plants against pathogen attack.[43]
An adult human in rest inhales 1.8 to 2.4 grams of oxygen per minute.[46] This amounts to more than 6 billion tonnes of oxygen inhaled by humanity per year.[47]
You will notice after reading this and my previous post: epa-and-carbon-dioxide How natural and important these things are to life of all living creatures on our planet.
but our representatives rely on us to be stupid and not pay attention to what they are doing. They continue to write stupid laws and create rediculous mandates and uncomprehensable legislations... Swine Flu was a Bio-test, and Martial Law is around the corner. This Carbon footprint is a scam just like H1N1 to scare you and tax you into submission.
These actions are Terrorist actions.
Please read the Def of Terrorist via Dictionary and compare that to the protocols that our Presidential Administrations have been subjecting us to for the past 12 years but more relative the past 2 years.
Remove the HEAD the body will fall- Q: X = ? X is the head The head controls the admin. Obama and members of congress are only the arms and legs Who is moving Obama?
Your true enemy is not Obama, nor is it congress.
Your true enemy is not Military or Law enforcement.
To Capture the enemy you MUST follow the money. WallStreet, Globalists, World Bankers, Memebers of the N.W.O. W.H.O. Bilderburgers, Rothchilds, Rockefellers Etc.. Those who possess the largest sum of money control the Economy. Ignoring it WILL NOT make it go away!
No comments:
Post a Comment