GRAPHITE 

graphite is an allotrope of carbon used as electrode in cells, pencil lead and as lubricant.

Graphite: properties

1.      Greyish black opaque

2.      Soft and slippery to touch

3.      Lighter than diamond

4.      Good conductor of electricity

5.      When burned only carbon dioxide is released and no residue is left.

6.      Symbol is C

Graphite: structure

1.      Graphite crystals consist of layer or sheets of carbon sheet.

2.      Each carbon atom of graphite crystal is joined to three other carbon atoms by strong covalent bonds to form flat hexagonal rings.

3.      The various layer of graphite are quite far from each other so no covalent bonds exist between the layers. So the various layers are held together by Van Der Waals forces.

Why is graphite soft substance?

Since the various layers of carbon atoms in graphite are joined by weak Van Der Waals forces, so the layers can slide over each other. Due to this sheet like arrangement graphite is a soft substance

Why is graphite a good conductor of electricity?

In a graphite crystal each carbon atom is joined to three carbon atoms by covalent bonds. Thus only three electrons are used in bond formation and one electron is left free. This free electron helps in conduction of electricity. Due to presence of electrons graphite crystal conducts electricity.

Uses of graphite

1.      Since graphite is soft, powdered graphite is used as lubricant for fast machinery.

2.      Since graphite is non explosive or non volatile it can be used for lubricating machines that operate at high temperature.

3.      Graphite powder can be used as dry lubricant and when mixed with petro it can be used as graphite grease.

4.      It can be used for making carbon or graphite electrodes in dry cell and electric arcs.

5.      Carbon brushes of electric motor are made of graphite, because it is a good conductor of electricity.

6.      Graphite is used for making the cores of our pencils because of its soft nature.