StructureThe crystalline form of carbon is graphite. It is also represented by the symbol C. In graphite each carbon atom is bonded to three carbon atoms. These three atoms are again bonded to three carbon atoms each, and so on. Thus a hexagonal layered structure is formed. The strongly bonded carbon atoms lie in the same layer. The atoms in one layer are bonded to the atoms in another layer by weak forces of attraction called Van der Waals forces. Graphite is a soft and slippery material since these layers can slip over each other.
Light cannot pass through the graphite crystal because of the irregular layered structure. Therefore graphite is a grey-black and opaque material.
Properties of Graphite
- Graphite occurs free in nature.
- Graphite is an opaque solid, grey-black in colour, with hexagonal crystals.
- It is soft and greasy to touch.
- It is a good conductor of heat and electricity.
- Its density is 2.2 g/cm3.
- It is stable to heat and possesses a high melting point of around 3700oC.
Uses of Graphite
- Graphite is used as a lubricant in fast moving machinery since graphite is soft and slippery.
- It is used to make crucibles to melt metals as graphite possess a high melting point.
- It is used as electrodes in batteries and electric furnaces as it is a good conductor of electricity.
- It is used as carbon brushes in dynamos and certain types of electric motors.
- It is used to make the core of lead pencils as it is soft and can mark paper.