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Binding of oxygen to a heme prosthetic group. Heme (American English), or haem (Commonwealth English, both pronounced /hi:m/ HEEM), is a ring-shaped iron-containing molecular component of hemoglobin, which is necessary to bind oxygen in the bloodstream. It is composed of four pyrrole rings with 2 vinyl and 2 propionic acid side chains. [1]
The rest of the Earth's crust is formed also of oxygen compounds, most importantly calcium carbonate (in limestone) and silicates (in feldspars). Water-soluble silicates in the form of Na 4 SiO 4, Na 2 SiO 3, and Na 2 Si 2 O 5 are used as detergents and adhesives. [6] Peroxides retain some of oxygen's original molecular structure ((− O-O −).
Solid oxygen forms at normal atmospheric pressure at a temperature below 54.36 K (−218.79 °C, −361.82 °F). Solid oxygen O 2 , like liquid oxygen , is a clear substance with a light sky-blue color caused by absorption in the red part of the visible light spectrum.
Tetraoxygen was first predicted in 1924 by Gilbert N. Lewis, who proposed it as an explanation for the failure of liquid oxygen to obey Curie's law. [1] Though not entirely inaccurate, computer simulations indicate that although there are no stable O 4 molecules in liquid oxygen, O 2 molecules do tend to associate in pairs with antiparallel spins, forming transient O 4 units. [2]
In chemistry and biology, reactive oxygen species (ROS) are highly reactive chemicals formed from diatomic oxygen (O 2), water, and hydrogen peroxide. Some prominent ROS are hydroperoxide (O 2 H), superoxide (O 2 −), [1] hydroxyl radical (OH.), and singlet oxygen. [2] ROS are pervasive because they are readily produced from O 2, which is ...
Most abbreviations can be found in the Chambers Dictionary as this is the dictionary primarily used by crossword setters. However, some abbreviations may be found in other dictionaries, such as the Collins English Dictionary and Oxford English Dictionary.
The number of oxygen atoms is used to define the size of the hydrogen polyoxide (e.g., hydrogen pentoxide contains a five-oxygen backbone). An oxidanyl group is a functional group or side-chain analog of hydrogen polyoxide that is attached to some structure other than just a hydrogen atom.
[2] [3] Oxygen atoms are joined to each other and to adjacent elements through single covalent bonds, denoted by dashes or lines. The O−O group in a peroxide is often called the peroxide group, though some nomenclature discrepancies exist. This linkage is recognized as a common polyatomic ion, and exists in many molecules.