Diamond has a three-dimensional covalent network that prevents electrons from moving freely. Which of the following is true about this statement?

• A. True
• B. False
• C. Not enough information
• D. Only at high temperatures

Answer: (A)

In a three-dimensional covalent network, atoms are linked by strong covalent bonds throughout the entire solid, forming a giant lattice. The electrons involved in bonding are localized in those bonds rather than roaming freely as charge carriers. Diamond is built from carbon atoms each forming four bonds in a rigid tetrahedral network, so there aren’t delocalized electrons to move through the structure. Because electrical conductivity requires mobile electrons (or holes) to carry charge, pure diamond behaves as an electrical insulator in the solid state. The statement is true for pure diamond; conduction would only arise under unusual conditions, such as with impurities or extreme circumstances, which is not the typical behavior.