explain graphite structure n how it conducts electricity???????????in detail
Carbon has four valence electrons and the orbital structure of the last energy level is 2s2 2p2. When two atoms of carbon bond together in a covalent way the molecular orbital that is formed can be of two types. First type of molecular orbital is sp3 and as it name says it contains 4 electrons. They are oriented to the 4 tips of a tetragonal prism, and thus form 4 equivalent sigma localized chemical bonds. This is the crystal structure of the diamond. Because sigma bonds localize the electrons between two neighbouring carbon atoms the diamond does not conduct electricity.
Second type of molecular orbital that carbon forms in a covalent bonding is sp2. It contains only 3 electrons and the fourth valence electron remains in a p orbital. The 3 electrons in the sp3 molecular orbital are oriented to the 3 vertices of an equilateral triangle. These are the sigma bondings that localize 3 of the valence electrons. The atoms form thus a plane hexagon. The fourth electron that remains in the p orbital forms one pi vertical bond (for each carbon atom) between two consecutive hexagonal planes. These pi bonds do not localize the electrons, and because of this they form a conduction band in which they are free to move.
This is why graphite conducts electricity. It has the fourth valence electron in a pi bond which allow it to move easily between different atoms.