Carbon

Allotropes Carbon can bond with itself in at least three different ways giving us 3 different materials –Diamond –Graphite –Buckyballs and nanotubes

Diamond Carbons are bonded via sp 3 hybridization to 4 other carbon atoms forming a giant network covalent compound.

Properties of Diamond High melting point due to strong directional covalent bonds (3550 C) Extremely hard because it is difficult to break atoms apart or move them in relation to one another No electrical conductivity because electrons are localized in specific bonds Insoluble in polar and non-polar solvents because molecular bonds are stronger than any intermolecular forces

Graphite Carbon atoms are bonded via sp2 hybridization. Carbon atoms form sheets of six sided rings with p-orbitals perpendicular from plane of ring.

Graphite Structure Carbon has 4 valence e- to bond with. 3 are used for closest atoms in rings. 1 is delocalized in p- orbitals The presence of p- orbitals allows for strong van der waals forces that hold the sheets together

Properties of Graphite Different from Diamond –Conducts electricity because of delocalized electrons –Slippery can be used as lubricant, sheets can easily slip past each other (think of a deck of cards) Same as Diamond –High melting point (higher actually because of delocalized e-, 3653 C) –Insoluble (same reason)

© Theodore Gray Ancient and modern methods for getting the lead (really graphite) into pencils. by-nc-sa: Adam Mulligan

How pencil is made

Graphite application

Graphite forms in metamorphosed sedimentary rocks as an alteration of organic material. public domain marble metamorphosed coal (anthracite) quartzite schist gneiss by-nc-sa: bcostin by-nc-sa: Ron Schott by-nc-sa: brewbooks

© Theodore Gray Soft and greasy-feeling, graphite is usually found in lumps… Graphite is mined. by-nc-nd: tridymite …but occasionally in crystals.

FedCenter public domain Disc brakes have graphite linings.

public domain Lightweight sports equipment, like tennis racquets and golf clubs, are often made from graphite. © Theodore Gray graphite lubricant Graphite is prized for both its strength and weakness.

© 2002 New England Meteoritical Services The other materials on this meteorite have weathered away, leaving only the graphite. Graphite is common in meteorites. by-nc-nd: Saxsbiker

US EPA/Region 6 Houston Laboratory Graphite Furnace Atomic Absorption Laboratory Graphite can withstand high heat. public domain Graphite crucibles of different sizes. These crucibles can withstand temperatures up to 1500°C.

San Francisco Maritime National Park Association Graphite is in generators, as the carbon brushes that conduct electricity. by-nc-nd: ingoism

© Theodore Gray Made in the late 1910s, the filament in this bulb has a graphite paste baked over a carbon core. Graphite is a good electrical conductor. Sandia Corporation silicon/graphite electrode

Neath Port Talbot County Borough Council, UK Some paints contain graphite. by-nc-nd: velo_city by-nc-nd: A30_Tsitika

by-nc-sa: tomblois State of California Alkaline batteries contain graphite rods. © Theodore Gray by-nc: Daniel W.

DoD/ANL In this photo, decontamination technicians remove the lead and graphite blocks from a nuclear reactor vessel. Graphite is used in nuclear power plants. by: lisaschaos

CIA The CIA found high-density graphite blocks stockpiled in Iraq, supporting the US's fear that Iraq had Weapons of Mass Destruction.

ORNL/U.S. DoE Oak Ridge Graphite Reactor, code-named "X-10," produced the world's first quantities of plutonium.