Which feature of graphite is responsible for its electrical conductivity? A) Strong covalent bonds. B) Delocalized electrons. C) Weak interlayer interactions. Or D) a high sublimating temperature.
This is a drawing of a layer of graphite from the top. At each intersection is a carbon atom bonded to three neighbors. Looking from the side, we can see that graphite consists of layers stacked one upon the other. While there are strong covalent bonds within the sheets themselves, there are only weak interactions between the layers. Each carbon atom has four electrons in its outer shell available for bonding, three of which are used in localized bonding to its neighbors, while the remaining electron is delocalized, contributing to stronger interactions within the layers and interactions between the layers.
Because of this giant covalent structure, graphite does not liquify under normal conditions, instead turning immediately from a solid to a gas when heated to 3642 degrees Celsius. Now that we’ve had a look at the origin of each of these features, we can start to consider which one might be responsible for graphite’s electrical conductivity. We can test whether something is conductive by using it to complete an electrical circuit. A cell or battery provides an electrical current charging up positive and negative electrodes.
When a piece of graphite bridges the gap between the two electrodes, a current will flow. This means that electrons can travel from one end to the other. The reason graphite can conduct electricity is because there are delocalized electrons that are mobile across the layers. This is the same reason why metals can conduct. When metallic atoms come together they sacrifice their valence electrons to a sea of delocalized electrons that can move between the ions.
Therefore, the feature of graphite responsible for its electrical conductivity is its delocalized electrons. The presence of strong covalent bonds, weak interlayer interactions, or a high sublimating temperature have no direct impact on electrical conductivity.