Allotropes of oxygen

different forms of the eight-proton element
There are several known allotropes of oxygen. The most familiar is molecular oxygen ( O2 ), present at significant levels in Earth ‘s atmosphere and besides known as dioxygen or triplet oxygen. Another is the highly reactive ozone ( O3 ). Others are :

  • Atomic oxygen (O1), a free radical.
  • Singlet oxygen (O2*), one of two metastable states of molecular oxygen.
  • Tetraoxygen (O4), another metastable form.
  • Solid oxygen, existing in six variously colored phases, of which one is O


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    and another one metallic.

Atomic oxygen [edit ]

Atomic oxygen, denoted O ( 3P ) or O ( 3P ), [ 1 ] is very reactive, as the single atoms of oxygen tend to promptly adhere with nearby molecules. On Earth ‘s surface, it does not exist naturally for very long, but in outer outer space, the presence of plenty of ultraviolet radiation results in a depleted Earth orb air in which 96 % of the oxygen occurs in nuclear form. [ 1 ] [ 2 ] Atomic oxygen has been detected on Mars by Mariner, Viking, and the SOFIA observatory. [ 3 ]

Dioxygen [edit ]

The most normally encountered allotrope of elemental oxygen is trio dioxygen, a diradical. The odd electrons participate in three-electron bond, shown here using dashed lines. The coarse allotrope of elemental oxygen on Earth, O
2, is generally known as oxygen, but may be called dioxygen, diatomic oxygen, molecular oxygen, or oxygen gas to distinguish it from the element itself and from the triatomic allotrope ozone, O
3. As a major component ( about 21 % by bulk ) of Earth ‘s atmosphere, elementary oxygen is most normally encountered in the diatomic shape. Aerobic organism turn the chemical energy stored in the watery sigma shackle of atmospheric dioxygen, the terminal oxidant in cellular respiration. [ 4 ] The land department of state of dioxygen is known as trio oxygen, 3 O2, because it has two odd electrons. The first aroused submit, singlet oxygen, 1 O2, has no odd electrons and is metastable. The doublet state requires an odd count of electrons, and so can not occur in dioxygen without gaining or losing electrons, such as in the superoxide ion ( O−
2 ) or the dioxygenyl ion ( O+
2 ). The crunch express of O
2 has a shackle length of 121 prime minister and a chemical bond energy of 498 kJ/mol. [ 5 ] It is a colorless flatulence with a boiling point of −183 °C ( 90 K ; −297 °F ). [ 6 ] It can be condensed from air by cooling with liquid nitrogen, which has a boiling charge of −196 °C ( 77 K ; −321 °F ). Liquid oxygen is pale amobarbital sodium in color, and is quite markedly paramagnetic ascribable to the odd electrons ; liquid oxygen contained in a flask suspended by a string is attracted to a magnet.

Singlet oxygen [edit ]

Singlet oxygen is the common list used for the two metastable states of molecular oxygen ( O2 ) with higher department of energy than the labor state trio oxygen. Because of the differences in their electron shells, singlet oxygen has different chemical and physical properties than trio oxygen, including absorbing and emitting light at different wavelengths. It can be generated in a photosensitize process by energy transfer from dye molecules such as rose bengal, methylene group blue or porphyrins, or by chemical processes such as ad-lib decay of hydrogen trioxide in water or the chemical reaction of hydrogen peroxide with hypochlorite .

ozone [edit ]

Triatomic oxygen ( ozone, O3 ) is a very reactive allotrope of oxygen that is a pale blasphemous accelerator at standard temperature and pressure. Liquid and hearty O3 have a deeper blasphemous semblance than ordinary O2, and they are unstable and explosive. [ 7 ] [ 8 ] In its natural gas phase, ozone is destructive to materials like rubberize and framework and is damaging to lung weave. [ 9 ] Traces of it can be detected as a barbed, chlorine-like smell, [ 6 ] coming from electric motors, laser printers, and photocopiers, as it is formed whenever air travel is subjected to an electrical drop. It was named “ ozon ” in 1840 by Christian Friedrich Schönbein, [ 10 ] from ancient greek ὄζειν ( ozein : “ to smell ” ) plus the suffix -on, normally used at the fourth dimension to designate a derived compound and anglicized as -one. [ 11 ] ozone is thermodynamically unstable and tends to react toward the more common dioxygen form. It is formed by reaction of integral O2 with atomic oxygen produced when UV radiotherapy in the upper berth atmosphere splits O2. [ 7 ] Ozone absorb powerfully in the ultraviolet and in the stratosphere functions as a carapace for the biosphere against mutagenic and other damage effects of solar UV radiotherapy ( see ozone layer ). [ 7 ] Tropospheric ozone is formed near the Earth ‘s surface by the photochemical decomposition of nitrogen dioxide in the exhaust of automobiles. [ 12 ] Ground-level ozone is an air travel pollutant that is specially harmful for senior citizens, children, and people with heart and lung conditions such as emphysema, bronchitis, and asthma. [ 13 ] The immune system produces ozone as an disinfectant ( see below ). [ 14 ]

Cyclic ozone [edit ]

Cyclic ozone is a theoretically predicted O3 atom in which its three atoms of oxygen bond in an equilateral triangle rather of an open angle.

Tetraoxygen [edit ]

Tetraoxygen had been suspected to exist since the early 1900s, when it was known as oxozone. It was identified in 2001 by a team led by Fulvio Cacace at the University of Rome. [ 15 ] The molecule O
4 was thought to be in one of the phases of solid oxygen late identified as O
8. Cacace ‘s team suggested that O
4 credibly consists of two dumbbell-like O
2 molecules loosely held together by induce dipole distribution forces .

Phases of solid oxygen [edit ]

There are six known distinct phases of solid oxygen. One of them is a dark-red O
8 bunch. When oxygen is subjected to a imperativeness of 96 GPa, it becomes metallic, in a similar manner to hydrogen, [ 16 ] and becomes more similar to the heavier chalcogens, such as selenium ( exhibiting a pink-red color in its elemental country ), tellurium and polonium, both of which show significant metallic character. At very low temperatures, this phase besides becomes superconducting .

References [edit ]

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