1. Carbon

2. Allotropes An allotrope is a different form of the same element
Carbon can bond with itself in different ways giving us 3 different materials
Diamond
Graphite
Buckyballs and nanotubes.
All are allotropes of Carbon.

3. Diamond
Each carbon is bonded with strong covalent bonds to 4 other carbon atoms forming a giant network covalent compound.

4. 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

5. Graphite
Each carbon atom is bonded to 3 other carbons with strong covalent bonds.
Carbon atoms form sheets of six sided rings with the 4th valence electron delocalised between them.

6. Graphite Structure
Carbon has 4 valence electrons to bond with. 3 are used for covalent bonds making rings.1 is delocalized.
van der waals forces hold the sheets together.

7. relative orientation of the layers
Graphite 1
relative orientation of the layers

8. Graphite 2
types of bond

9. 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 electrons, 3653C)
Insoluble (same reason)

10. Fullerenes Buckyballs: spherical Nanotubes: tube shaped
Both have very interesting properties
Super strong
Conduct electricity and heat with very low resistance, a SUPERCONDUCTOR

11. Buckyballs
Carbon atoms bond in units of e.g.,60 atoms (C60) forming a structure similar to a football with interlocking six sided and five sided rings (note, other types also exist).
Presence of delocalised electrons leads to
High electrical conductivity
Stronger bonds so
super strong materials