Author: Leonard Krugman
Carbon is occasionally found in nature in a stable crystalline form, the diamond. In this form, each valence-ring electron, moving around the nucleus of a carbon atom, coordinates its motion with that of a corresponding valence-ring electron of a neighboring atom. Under these conditions, the electron pair forms a covalent bond. Equilibrium between the repulsion and attraction forces of the atoms is reached at this time, the previously loosely bound valence-ring electrons now are tightly bound to their nucleus, and cannot easily be dislodged. This effectively reduces the number of available free electrons in the crystal, and hence reduces its conductivity. Thus, carbon, generally a semiconductor, becomes an insulator in the diamond form.