chem! (40 points)

In graphite, carbon atoms are joined together by strong covalent bonds to form layers of carbon atoms. The layers are held together by weak van der Waals' forces, and the layers can easily slip between each other when a force is exerted. Therefore, graphite is soft because the layers can easily slip between each other when a force is exerted.

GRAPHITE

structure
Each C atom is covalently bonded to 3 other C atoms
in trigonal planar to form a multi-layer structure.
Adjacent layers are held by van der Waals' forces

co-ordination no./ hybridization
3 / sp2

b.p.
3700 °C
strong C-C covalent bonds have to be broken in melting / boiling

***strength
soft; weak van der Waals' forces
*** allow layers to slip over each other easily***

electrical conductivity
good conductor of electricity;
each C atom has a delocalized electron which
can move freely along the same layer

uses
electrodes, lubricants, pencils

As diamond is also polymer of carbon but it is the hardest substance in the world . Compare to graphite is also pure carbon polymer but it is quite soft . This is because the arrangement of the carbon atom with weakly bonding strength so the carbon atoms can move to a greater distance . The solfness of graphite makes it more suitable to be used in pencil as the black color coating . When you write you exert forces onto the tip of the graphite which forms a black dye lining coated on the paper . This becomes the marks of writing .