What is the structure of diamond like?

The structure of diamond is characterized by each carbon atom forming four covalent bonds with other carbon atoms in a three-dimensional tetrahedral arrangement. This arrangement creates a very strong and rigid lattice structure that contributes to diamond’s exceptional hardness and high melting point. The tetrahedral bonding allows for a dense packing of atoms which is responsible for diamond's unique properties, such as its high thermal conductivity and brilliance when cut properly.

The other options do not accurately describe the diamond structure. For instance, a hexagonal layer refers more to materials like graphite, which has a layered structure due to the planar arrangements of carbon atoms. A loose chain of carbon atoms suggests a less stable arrangement that does not reflect the strong bonding found in diamond. Finally, a spherical arrangement is not representative of the crystalline structure of diamond, which is inherently structured and defined rather than being spherical. Thus, the description of each carbon atom forming four covalent bonds perfectly encapsulates the key characteristic of diamond's structure.