Structure of graphite consist of a two dimensional sheet like network joined together in hexagonal rings. These layers are held together by weak van der Waals' forces. In graphite each carbon atom is bonded to three others, forming $sp^2$ hybrid bonds. The fourth electron forms a $\pi$-bond. Graphite is a conductor of electricity which is due to the fact that all the carbon bonds being not satisfied. Thus, some of the electrons are free to move through the crystal.
P block elements are those in which the last electron enters any of the three p-orbitals of their respective shells. Since a p-subshell has three degenerate p-orbitals each of which can accommodate two electrons, therefore in all there are six groups of p-block elements.
P block elements are shiny and usually a good conductor of electricity and heat as they have a tendency to lose an electron. You will find some amazing properties of elements in a P-block element like gallium. It’s a metal that can melt in the palm of your hand. Silicon is also one of the most important metalloids of the p-block group as it is an important component of glass.