Saturday, June 6, 2009

Strange Carbon Allotropes, Part 2

This is part 2 of 2 on strange carbon allotropes, part 3 of 3 on carbon, and part 5 of at least 6 on somewhat obscure and long-winded chemistry topics.

Atomic carbon, C1, is a short-lived species of monatomic carbon that forms in the arc between two carbon rods under high voltage and certain conditions - the same way as making buckyballs. Other than that, the article is greek to me.

Diatomic carbon, C2, is a normally impossible molecule. Normally a quadruple bond would be the only way that 2 carbons, with 4 valence electrons each, could bond. However, a quadruple bond includes a delta bond, which carbon cannot form - it has only p and s electrons, and not the d electrons for a delta bond. Instead, they form an unstable double bond with 2 pi bonds, but no sigma bond. It's rather rare; however, emission of diatomic carbon creates most of the light from fainter carbon.

Tricarbon, C3, is a small carbon cluster that, like diatomic carbon, appear mostly in the ion clouds of comets. It can also be found in interstellar space and in stellar atmospheres. It also appears in the middle of certain combustion reactions, but never as a product.

Prismane C8 is a theorized but not yet created metastable allotrope which would take the form of an elongated triagonal dipyramid.

Three other predicted forms are known. Hexagonite would have the same hexagonal layers as graphite, but with another carbon atom in the center of ech unit cell. Second, at extremely high pressures, diamond may act metallic. Third, at pressures above 1 terapascals, diamond may morph into an 8-atom cubic phase.

Fullerenes are a set of organized carbon structures. they include tubes (nanotubes), buckyballs, and nanobuds (buckyballs connected to nanotubes). Buckyballs are roughly spherical clusters of carbon atoms. C60, C70, and C540 balls are known, as well as a possible B80 boron buckyball.
Buckyballs can hold atom(s) inside them; this could be used to store simgle atoms or molecules for certain applications in nanotechnology.

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