Question

The hardest substance known is diamond. Which best describes the structure of diamond?

A. A 3D network lattice of covalently bonded carbon atoms.
B. A 2D network lattice of covalently bonded carbon atoms.
C. A 3D network lattice of carbon ions held together by ionic bonds.
D. A 3D network lattice of carbon ions in a sea of mobile valence electrons held together by metallic bonds.
E. A 3D network lattice of carbon atoms held together by hydrogen bonding and dispersion forces.

Answer 1

Diamond is a 3D network lattice of covalently bonded carbon atoms, forming a covalent network solid known for its extreme hardness and high melting point.

Step-by-step explanation:

The hardest substance known is diamond, which is best described as a 3D network lattice of covalently bonded carbon atoms. Diamond's structure is composed entirely of carbon atoms, each bonded to four other carbon atoms, forming a tetrahedral geometry. This extensive network of covalent bonds throughout the crystal makes diamond a covalent network solid, contributing to its remarkable hardness and high melting point.

In diamond, the carbon atoms create a gigantic molecule, where melting this substance requires breaking all the covalent bonds, a process requiring extremely high temperatures. Hence, diamond is one of the highest-melting substances known, and it does not melt under normal conditions but sublimates to a gas at temperatures above 3,500°C.