Why does graphite have a high melting point?

• A. The strong covalent bonds take a lot of energy to break
• B. Weak intermolecular forces
• C. It is ionic
• D. It is amorphous

Answer: (A)

Melting point depends on how strong the bonds holding the solid together are. Graphite is a giant covalent solid in which each carbon atom forms strong covalent bonds to three others in a planar sheet. To melt graphite, you would have to break these many strong covalent bonds throughout the structure, which takes a lot of energy. The layers are held together by weaker van der Waals forces, but melting is dominated by breaking the in-plane covalent bonds, not by overcoming the interlayer attractions. That’s why graphite has a very high melting point. It isn’t ionic and it isn’t amorphous; it has a crystalline, layered covalent structure.