Graphite electrical mobility

As a result of the mobility of the electrons in n orbitals, graphite is a conductor of electricity. It is also the form of carbon used as the thermodynamic standard state. On the other hand, diamond contains carbon atoms that are bonded to four others, so all of the electrons are used in localized bonding, and it is a nonconductor that has the structure shown in Figure 13.12. 

Solid sodium chloride does not conduct electricity. Its ions vibrate about fixed positions, but they are not free to move throughout the crystal. Molten (melted) NaCl, however, is an excellent conductor because its ions are freely mobile. Consider a cell in which a source of direct current is connected by wires to two inert graphite electrodes (Figure 21-2 a). They are immersed in a container of molten sodium chloride. When the current flows, we observe the following. 

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