The document discusses three allotropes of carbon: diamond, graphite, and buckminsterfullerence. Diamond has a rigid structure of carbon atoms bonded together, giving it properties of hardness and high melting point. Graphite has layers of carbon atoms bonded weakly, making it softer and able to conduct electricity. Buckminsterfullerence is a spherical cluster of 60 carbon atoms that is a dark solid.

1. The various physical forms in which
an element can exit are called
allotropes of the element.
Allotropes are of three types:
 Diamond
 Graphite
 Buckminsterfullerence

3. 
A diamond crystal is a
giant molecule of carbon
atoms . Each carbon
atom is linked to other
carbon atoms by strong
covalent bonds. The rigid
structure of diamond
makes it a very hard
substance.

4.  The melting point of diamond
is very high , being more than
3500˚c. So lot of heat energy is
required to break the network
of diamond.
 It is a non conductor of
electricity because there is no
free electrons in a diamond
crystal.

5.  Diamond are used in
cutting instruments like
glass cutters and in rock
drilling equipment.
 Diamonds are used for
making jewellery.
 Sharp edged diamonds
are used by eye surgeons
as a tool to remove
catract from eyes.

6.  Graphite is a greyish
black opaque substance.
 It is lighter than diamond
and is soft and slippery to
touch .
 It conduct electricity .
 It is made up of carbon
atoms only .

7.  The structure of graphite is very
different from that of diamond. It
consists of layers of carbon atoms
or sheet of carbon atoms.
 Each carbon atoms in a graphite
layer is joined to three other
carbon atoms by strong covalent
bonds to form flat hexagonal
rings.
 The various layers of carbon
atoms in graphite are held
together by weak van der waals
forces.

8. • Due to the sheet like
structure ,graphite is
comparatively soft
substance.
• Graphite is good
conductor of
electricity because
due to the presence
of free electrons.

9. Graphite can be used for
lubricating those machine
parts which operate at very
high temperature.
Graphite is used for making
graphite electrodes in dry
cells and electric arcs.
Graphite is used for making
the cores of our pencils
called pencil leads.

10. BUCKMINSTERFULLERENCE
Buckminsterfullerence is an
allotrope of carbon
containing clusters of
60carbon atoms joined
together to form spherical
molecules.
It is a dark solid at room
temperature.

11. 1. Explain why, diamond has a high melting
point.
2. Why is graphite a good conductor of
electricity but diamond is a non –conductor
of electricity ?
3. Give any two differences between diamond
and graphite.
4. Explain why, diamond is hard while graphite
is soft.
5. Explain why, diamonds are used in drilling
equipment.

12. Thank you…..