In order to produce smaller amounts of oxygen, O2 from the air by adsorption of other gases can be separated. These air flows through molecular sieves. In this case, nitrogen and carbon dioxide are adsorbed and only O2 and argon pass through. This is used in O2 concentrator mainly used medically (oxygen for energy).
The development of O2 concentration in atmosphere is described in article Development of earth's atmosphere. The O2 allotrope O3 Ozone is present in atmosphere at low concentrations. In space, O2 is the third most abundant element after hydrogen and helium. The mass fraction of O2 is in solar system about 0.8% (this corresponds to an (atomic) number fraction of about 500 ppm).
Oxygen is not created in primordial nucleosynthesis, but is produced in relatively large amounts in giant stars by helium burning. It is first formed from three helium nuclei 12C (Triple-alpha process), which subsequently merged with another helium nucleus to 16O. 18O is formed by fusion of 4He with a 14N nucleus.
O2 is slightly soluble in water. The solubility depends on the pressure and the temperature. It increases with decreasing temperature and increasing pressure. At 0 degrees C and an O2 partial pressure of air of 212 hPa dissolve in pure water 14.16 mg / l oxygen. In oxygen-gas discharge Spectrum, the molecular orbitals of O2 are stimulated to emit light. The operating conditions are a pressure of 5-10 mbar, a high voltage of 1.8 kV, a current of 18 mA and a frequency of 35 kHz. During the recombination of ionized gas molecules, the characteristic color spectrum is emitted. In this case, a small part, caused reversibly formed by the supply of energy ozone.
Most white dwarfs, which are the final state of 97% of all stars in prior theory, exist side by helium and carbon to a large extent of oxygen. Technically O2 is today almost exclusively obtained by rectification of air. The method in 1902, first developed by Carl von Linde (Linde process) and designed by Georges Claude economically viable. Small amounts arising as a by-product in production of hydrogen by electrolysis of water.
Since these orbitals are completely filled with electrons, they do not contribute to binding. From the 2p orbitals are a total of six molecular orbitals with different energy level. The orbitals have this same energy. Electrons are distributed in molecular orbitals, it comes to following breakdown of eight p-electrons. These two valence electrons determine the properties of O2 molecule. O2 has allowed a total of three and energetically accessible quantum states for the distribution of these electrons.
Occupation of energy levels of molecular orbitals of O2 in ground and excited states. In ground state the spins of two valence electrons of Hund's rule are arranged in parallel in obedience. It is a triplet state with the term symbol 3g. It is the state with the lowest energy. Through the two unpaired electrons, the two orbitals are half occupied. This caused some characteristic properties, such as the diradical character and the paramagnetism of O2 molecule.
The most common stable oxygen isotope 16O (99.76%), in addition still comes 18O (0.20%) and 17O (0.037%) before. In addition to the stable oxygen isotopes are still a total of 13 unstable, radioactive nuclides from 12O to 28O are known which are artificially produced. Their half lives often are only milliseconds to seconds, with two minutes 15O this case has the longest half-life, and is frequently used in positron emission tomography.
The development of O2 concentration in atmosphere is described in article Development of earth's atmosphere. The O2 allotrope O3 Ozone is present in atmosphere at low concentrations. In space, O2 is the third most abundant element after hydrogen and helium. The mass fraction of O2 is in solar system about 0.8% (this corresponds to an (atomic) number fraction of about 500 ppm).
Oxygen is not created in primordial nucleosynthesis, but is produced in relatively large amounts in giant stars by helium burning. It is first formed from three helium nuclei 12C (Triple-alpha process), which subsequently merged with another helium nucleus to 16O. 18O is formed by fusion of 4He with a 14N nucleus.
O2 is slightly soluble in water. The solubility depends on the pressure and the temperature. It increases with decreasing temperature and increasing pressure. At 0 degrees C and an O2 partial pressure of air of 212 hPa dissolve in pure water 14.16 mg / l oxygen. In oxygen-gas discharge Spectrum, the molecular orbitals of O2 are stimulated to emit light. The operating conditions are a pressure of 5-10 mbar, a high voltage of 1.8 kV, a current of 18 mA and a frequency of 35 kHz. During the recombination of ionized gas molecules, the characteristic color spectrum is emitted. In this case, a small part, caused reversibly formed by the supply of energy ozone.
Most white dwarfs, which are the final state of 97% of all stars in prior theory, exist side by helium and carbon to a large extent of oxygen. Technically O2 is today almost exclusively obtained by rectification of air. The method in 1902, first developed by Carl von Linde (Linde process) and designed by Georges Claude economically viable. Small amounts arising as a by-product in production of hydrogen by electrolysis of water.
Since these orbitals are completely filled with electrons, they do not contribute to binding. From the 2p orbitals are a total of six molecular orbitals with different energy level. The orbitals have this same energy. Electrons are distributed in molecular orbitals, it comes to following breakdown of eight p-electrons. These two valence electrons determine the properties of O2 molecule. O2 has allowed a total of three and energetically accessible quantum states for the distribution of these electrons.
Occupation of energy levels of molecular orbitals of O2 in ground and excited states. In ground state the spins of two valence electrons of Hund's rule are arranged in parallel in obedience. It is a triplet state with the term symbol 3g. It is the state with the lowest energy. Through the two unpaired electrons, the two orbitals are half occupied. This caused some characteristic properties, such as the diradical character and the paramagnetism of O2 molecule.
The most common stable oxygen isotope 16O (99.76%), in addition still comes 18O (0.20%) and 17O (0.037%) before. In addition to the stable oxygen isotopes are still a total of 13 unstable, radioactive nuclides from 12O to 28O are known which are artificially produced. Their half lives often are only milliseconds to seconds, with two minutes 15O this case has the longest half-life, and is frequently used in positron emission tomography.
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