Explain the structure of graphite giving the reason for its softness as well as its electrical conductivity.

Explanation

A good conductor of electricity graphite carbon atom is `sp^(3)` hybridised . Out of the four valency electrons in each carbon atom only three electrons one from 2s and two from 2p are involved in hybridisation . One space electron in its `2p_(z)` orbital is left free. These `2p_(z)` orbital overlap to from deloclised `pi` system which extends above and below each layer . In this delocalised space electrons are free to move within the layer and hece graphite is a good conductor of electricity. The conductivity of graphite perpendicular to the plane of the layers of hexagons is low and increases with increase in temperature signifying that graphite is a semiconductor in that direction. The electrical conductivity is much higher paraller to the plane but decreases as the temperature is raised . It is a soft flaky and slippery substance : In graphite each layer of the hexagons are hold together by a weak Van der Waal's force of attraction at a large distance of 3.40 Å. Even the slight pressure causes the layers to slide over one another . Hence graphite is soft flaky and slippery. Graphite is used as a lubricant .