Oxygen - Wikipedia. Oxygen,  8. OLiquid oxygen boiling. Spectral lines of oxygen. General properties.

Pronunciation. OK- sij- . It is a member of the chalcogengroup on the periodic table and is a highly reactivenonmetal and oxidizing agent that readily forms oxides with most elements as well as other compounds.

This is an important part of the atmosphere and diatomic oxygen gas constitutes 2. Earth's atmosphere. Most of the mass of living organisms is oxygen as a component of water, the major constituent of lifeforms. Conversely, oxygen is continuously replenished by photosynthesis, which uses the energy of sunlight to produce oxygen from water and carbon dioxide. Oxygen is too chemically reactive to remain a free element in air without being continuously replenished by the photosynthetic action of living organisms. Another form (allotrope) of oxygen, ozone (O3), strongly absorbs ultraviolet UVB radiation and the high- altitude ozone layer helps protect the biosphere from ultraviolet radiation. But ozone is a pollutant near the surface where it is a by- product of smog.

At low earth orbit altitudes, sufficient atomic oxygen is present to cause corrosion of spacecraft. The name oxygen was coined in 1. Antoine Lavoisier. Its name derives from the Greek roots . In his work Pneumatica, Philo observed that inverting a vessel over a burning candle and surrounding the vessel's neck with water resulted in some water rising into the neck. Many centuries later Leonardo da Vinci built on Philo's work by observing that a portion of air is consumed during combustion and respiration.

English chemist John Mayow (1. Becher, and modified by the chemist Georg Ernst Stahl by 1. One part, called phlogiston, was given off when the substance containing it was burned, while the dephlogisticated part was thought to be its true form, or calx. Fastest Windows 7 Loader Activator Daz. Air did not play a role in phlogiston theory, nor were any initial quantitative experiments conducted to test the idea; instead, it was based on observations of what happens when something burns, that most common objects appear to become lighter and seem to lose something in the process. Rather than combustion or corrosion occurring as a result of the decomposition of phlogiston compounds into their base elements with the phlogiston being lost to the air, it is in fact the result of oxygen from the air combining with the base elements to produce oxides. Indeed, one of the first clues that the phlogiston theory was incorrect was that metals gain weight in rusting (when they were supposedly losing phlogiston). Discovery. Oxygen was first discovered by Swedish pharmacist Carl Wilhelm Scheele.

He had produced oxygen gas by heating mercuric oxide and various nitrates in 1. That document was published in 1.

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After breathing the gas himself, he wrote: . Priestley visited Lavoisier in October 1. Scheele also posted a letter to Lavoisier on September 3. Lavoisier never acknowledged receiving it (a copy of the letter was found in Scheele's belongings after his death). He also noted that the tin had increased in weight and that increase was the same as the weight of the air that rushed back in. This and other experiments on combustion were documented in his book Sur la combustion en g. Azote later became nitrogen in English, although it has kept the name in French and several other European languages.

This is partly due to a poem praising the gas titled . For example, Dalton assumed that water's formula was HO, giving the atomic mass of oxygen was 8 times that of hydrogen, instead of the modern value of about 1. Using a cascade method, Swiss chemist and physicist Raoul Pierre Pictetevaporated liquid sulfur dioxide in order to liquefy carbon dioxide, which in turn was evaporated to cool oxygen gas enough to liquefy it.

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He sent a telegram on December 2. French Academy of Sciences in Paris announcing his discovery of liquid oxygen. Oxygen was liquified in a stable state for the first time on March 2. Polish scientists from Jagiellonian University, Zygmunt Wr. Both men lowered the temperature of air until it liquefied and then distilled the component gases by boiling them off one at a time and capturing them.

This method of welding and cutting metal later became common. Goddard became the first person to develop a rocket engine that burned liquid fuel; the engine used gasoline for fuel and liquid oxygen as the oxidizer. Goddard successfully flew a small liquid- fueled rocket 5. March 1. 6, 1. 92. Auburn, Massachusetts, US.

The bond can be variously described based on level of theory, but is reasonably and simply described as a covalent double bond that results from the filling of molecular orbitals formed from the atomic orbitals of the individual oxygen atoms, the filling of which results in a bond order of two. More specifically, the double bond is the result of sequential, low- to- high energy, or Aufbau, filling of orbitals, and the resulting cancellation of contributions from the 2s electrons, after sequential filling of the low . An electron configuration with two unpaired electrons, as is found in dioxygen orbitals (see the filled . Hence, the ground state of the O2 molecule is referred to as triplet oxygen. Because of its unpaired electrons, triplet oxygen reacts only slowly with most organic molecules, which have paired electron spins; this prevents spontaneous combustion. That is, they impart magnetic character to oxygen when it is in the presence of a magnetic field, because of the spinmagnetic moments of the unpaired electrons in the molecule, and the negative exchange energy between neighboring O2 molecules.

It is much more reactive with common organic molecules than is molecular oxygen per se. In nature, singlet oxygen is commonly formed from water during photosynthesis, using the energy of sunlight. O2 has a bond length of 1. J. Other aspects of O2 are covered in the remainder of this article.

Trioxygen (O3) is usually known as ozone and is a very reactive allotrope of oxygen that is damaging to lung tissue. It was proven in 2. O2 to 2. 0 GPa, is in fact a rhombohedral. O8cluster. The green color is similar to the color of an . Water in equilibrium with air contains approximately 1 molecule of dissolved O2 for every 2 molecules of N2 (1: 2), compared with an atmospheric ratio of approximately 1: 4.

The solubility of oxygen in water is temperature- dependent, and about twice as much (1. High- purity liquid O2 is usually obtained by the fractional distillation of liquefied air. The most stable are 1. O with a half- life of 1. O with a half- life of 7.

Oxygen is the third most abundant chemical element in the universe, after hydrogen and helium. It is also the major component of the world's oceans (8. The O2 surrounding those planets is produced solely by ultraviolet radiation on oxygen- containing molecules such as carbon dioxide. The unusually high concentration of oxygen gas on Earth is the result of the oxygen cycle. This biogeochemical cycle describes the movement of oxygen within and between its three main reservoirs on Earth: the atmosphere, the biosphere, and the lithosphere.

The main driving factor of the oxygen cycle is photosynthesis, which is responsible for modern Earth's atmosphere. Photosynthesis releases oxygen into the atmosphere, while respiration, decay, and combustion remove it from the atmosphere. In the present equilibrium, production and consumption occur at the same rate of roughly 1/2.

The increased solubility of O2 at lower temperatures (see Physical properties) has important implications for ocean life, as polar oceans support a much higher density of life due to their higher oxygen content. Scientists assess this aspect of water quality by measuring the water's biochemical oxygen demand, or the amount of O2 needed to restore it to a normal concentration. Seawater molecules that contain the lighter isotope, oxygen- 1. Marine organisms then incorporate more oxygen- 1.