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[412] [n 43] In organic chemistry, carbon can form complex cations – termed carbocations – in which the positive charge is on the carbon atom; examples are CH + 3 and CH + 5, and their derivatives. [413] Graphite is an established solid lubricant and behaves as a semiconductor in a direction perpendicular to its planes. [407]
The elements commonly classified as metalloids are boron, silicon, germanium, arsenic, antimony and tellurium. [n 4] The status of polonium and astatine is not settled. Most authors recognise one or the other, or both, as metalloids; Herman, Hoffmann and Ashcroft, on the basis of relativistic modelling, predict astatine will be a monatomic metal.
When exposed to an oxidant, [156] especially a liquid oxidant, [155] the high surface-area to volume ratio of p-Si creates a very efficient burn, accompanied by nano-explosions, [152] and sometimes by ball-lightning-like plasmoids with, for example, a diameter of 0.1–0.8 m, a velocity of up to 0.5 m/s and a lifetime of up to 1s. [157]
It is the softest of the commonly recognised metalloids. Tellurium reacts with boiling water, or when freshly precipitated even at 50 °C, to give the dioxide and hydrogen: Te + 2 H 2 O → TeO 2 + 2 H 2. It has a melting point of 450 °C and a boiling point of 988 °C. Tellurium has a polyatomic (CN 2) hexagonal crystalline structure.
For example, ferrocene, [(η 5-C 5 H 5) 2 Fe], has two cyclopentadienyl ligands giving a hapticity of 5, where all five carbon atoms of the C 5 H 5 ligand bond equally and contribute one electron to the iron center. Ligands that bind non-contiguous atoms are denoted the Greek letter kappa, κ. [7] Chelating κ2-acetate is an example.
The Inorganic Crystal Structure Database (ICSD) in its definition of "inorganic" carbon compounds, states that such compounds may contain either C-H or C-C bonds, but not both. [7] The book series Inorganic Syntheses does not define inorganic compounds. The majority of its content deals with metal complexes of organic ligands. [8]
Carbon compounds are defined as chemical substances containing carbon. [1] [2] More compounds of carbon exist than any other chemical element except for hydrogen. Organic carbon compounds are far more numerous than inorganic carbon compounds. In general bonds of carbon with other elements are covalent bonds.
Native copper Native gold Native silver Native sulfur Diamond (native carbon) Native element minerals are those elements that occur in nature in uncombined form with a distinct mineral structure. The elemental class includes metals, intermetallic compounds, alloys, metalloids, and nonmetals.