Allotropes of Carbon.ppt

difference between allotropes of 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 pointdue to strong directional
covalent bonds (3550 C)
Extremely hardbecause it is difficult to break
atoms apart or move them in relation to one
another
No electrical conductivitybecause electrons are
localized in specific bonds
Insolublein 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 4
th
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. 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 (C
60) 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