Which term describes a crystalline form in which each carbon atom is bonded to four other carbon atoms?

Which term describes a crystalline form in which each carbon atom is bonded to four other carbon atoms?

• A. Diamond
• B. Graphite
• C. Fullerene
• D. Nanotube

Answer: (A)

The key idea is a three-dimensional network where every carbon atom forms four covalent bonds in a tetrahedral arrangement. In diamond, each carbon is sp3 hybridized and links to four neighboring carbons, creating a rigid, crystal-like lattice that goes on in all directions. This is why diamond is described as a crystalline form with each carbon bonded to four others. Other forms of carbon don't fit this description. Graphite has carbon atoms bonded to three others in flat, layered sheets; the layers stack with weak forces between them, so not every atom reaches four bonds. Fullerene structures are closed cages where most carbons bond to three neighbors, forming a soccer-ball–like shape rather than a full 3D tetrahedral network. Nanotubes are built from rolled graphene sheets, where most carbons also bond to three neighbors, producing tubular structures rather than the tetrahedral network seen in diamond. So the term that matches a crystalline form with each carbon bonded to four others is diamond.

The key idea is a three-dimensional network where every carbon atom forms four covalent bonds in a tetrahedral arrangement. In diamond, each carbon is sp3 hybridized and links to four neighboring carbons, creating a rigid, crystal-like lattice that goes on in all directions. This is why diamond is described as a crystalline form with each carbon bonded to four others.

Other forms of carbon don't fit this description. Graphite has carbon atoms bonded to three others in flat, layered sheets; the layers stack with weak forces between them, so not every atom reaches four bonds. Fullerene structures are closed cages where most carbons bond to three neighbors, forming a soccer-ball–like shape rather than a full 3D tetrahedral network. Nanotubes are built from rolled graphene sheets, where most carbons also bond to three neighbors, producing tubular structures rather than the tetrahedral network seen in diamond.

So the term that matches a crystalline form with each carbon bonded to four others is diamond.