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It is an allotrope of carbon in the form of a plane of sp 2-bonded atoms with a molecular bond length of 0.142 nm (1.42 Å). In a graphene sheet, each atom is connected to its three nearest carbon neighbors by σ-bonds , and a delocalized π-bond , which contributes to a valence band that extends over the whole sheet.
In general bonds of carbon with other elements are covalent bonds. Carbon is tetravalent but carbon free radicals and carbenes occur as short-lived intermediates. Ions of carbon are carbocations and carbanions are also short-lived. An important carbon property is catenation as the ability to form long carbon chains and rings. [3]
In physics and engineering, permeation (also called imbuing) is the penetration of a permeate (a fluid such as a liquid, gas, or vapor) through a solid.It is directly related to the concentration gradient of the permeate, a material's intrinsic permeability, and the materials' mass diffusivity. [1]
This may also be called the intrinsic permeability or specific permeability. These terms refer to the quality that the permeability value in question is an intensive property of the medium, not a spatial average of a heterogeneous block of material equation 2.28 [clarification needed] [further explanation needed]; and that it is a function of ...
Carbon-based compounds form the basis of all known life on Earth, and the carbon-nitrogen-oxygen cycle provides a small portion of the energy produced by the Sun, and most of the energy in larger stars (e.g. Sirius). Although it forms an extraordinary variety of compounds, most forms of carbon are comparatively unreactive under normal conditions.
Likewise, under standard conditions, graphite is the most stable form of carbon. Therefore, it is used in thermochemistry as the standard state for defining the heat of formation of carbon compounds. Graphite conducts electricity, due to delocalization of the pi bond electrons above and below the planes of the carbon atoms. These electrons are ...
Carbon atoms bond readily to other carbon atoms; this allows the building of arbitrarily long macromolecules and polymers in a process known as catenation. [ 20 ] [ 21 ] [ 22 ] "What we normally think of as 'life' is based on chains of carbon atoms, with a few other atoms, such as nitrogen or phosphorus", per Stephen Hawking in a 2008 lecture ...
Also acid ionization constant or acidity constant. A quantitative measure of the strength of an acid in solution expressed as an equilibrium constant for a chemical dissociation reaction in the context of acid-base reactions. It is often given as its base-10 cologarithm, p K a. acid–base extraction A chemical reaction in which chemical species are separated from other acids and bases. acid ...