Allotropy may be defined as existence of an element in two or more different forms that has same chemical properties but different physical properties.
Carbon element exists in two allotropic forms:-
- Diamond &
- Graphite.
Graphite is an important allotropic form of carbon. It is a good conductor of electricity. It is used extensively for making core of electrochemical cells (Dry Cell) and Lead pencil. Graphite has a 3 D network structure. It consists of only carbon atoms. In graphite each carbon atom is covalently bonded to three other carbon atoms. This arrangement makes layers of hexagonal rings that can slip past one another. In graphite each carbon atom has a free electron in its outermost energy shell. This free electron is responsible for conductivity of electricity through graphite.