CARBON Allotropes: Structure: hcp (hexagonal close-packed) Melting point 3527 ºC Amorphous: very small particles of graphite (e.g. soot). Graphite: infinite lattice, layer structure where each atom bonds to three neighbours; most stable form and is one of the softest known materials. (Hardness: Mineral 0.5) Fullerenes: discrete closed cages such as buckminsterfullerene, C60 (called buckyballs). Nanotubes: open ended giving the appearance of rolled graphite. Diamond: lattice where each atom bonds to four neighbours in a tetrahedral arrangement; is one of the hardest materials (Hardness: Mineral 10.0). -microscopic diamonds: in some meteorites. - natural diamonds: in ancient volcanic "pipes" or from ocean floor. Natural Occurrence: -Human Body (e.g. 100 1b. body weight = 10.4 kg C, 150 lb. Body weight =15.7 kg C) *University of Sheffield (Mike Piff) - calcium carbonate (limestone); -coal, petroleum, and natural gas are chiefly hydrocarbons; - natural diamonds: in ancient volcanic "pipes" (South Africa) or from ocean floor. - microscopic diamonds: in some meteorites. -carbon dioxide in the atmosphere of the earth/planets and dissolved in all natural waters. Industrial Uses: fuels, petrochemical industry C-14 isotope used in archaeological dating graphite:, pencils, dry lubricants, , golf shafts, fishing rods, composite hockey sticks nanotubes: conductive and high-strength composites; energy storage devices; sensors, semiconductors. Buckyballs: drug delivery systems Environmental Consequences: CO in car exhaust; CN- in pollution from mining; Gases are explosion hazards [e.g.: methane (CH4) and acetylene (HCCH)]. DIAMOND BUCKEYBALL GRAPHITE NANOTUBE Bucky Balls for H2 Storage? GEMZ Corp., a nanotech startup, is set to acquire an exclusive license to a new thermal acoustic process for the production of bucky balls—C60—to be used for the storage of hydrogen. While the technology is still conceptual, and its development is “uncertain and fraught with risk,” according to GEMZ, it could open the way for hydrogen storage in C60 at a cost two orders of magnitude lower than current technology permits. GEMZ estimates that the thermal acoustic technique is potentially more efficient than the four methods currently used for producing C60, all of which consume too much energy in the manufacturing process for them to be cost effective. Bucky balls, also known as Buckminster Fullerenes, after the architect Buckminster Fuller, are the roundest and most symmetrical large molecule known. Discovered in 1985 by Professors Smalley, Curl and Kroto (for which they won the Nobel Prize in 1996), bucky balls are hollow clusters of 60 carbon atoms, shaped like soccer balls. The C60 molecule has the special property of being able to absorb large numbers of hydrogen atoms without disrupting the bucky ball structure. This property suggests that C60 may be a better storage medium for hydrogen than metal hydrides, the best current material, and hence possibly a key factor in the development of hydrogen-fueled vehicles.