Final answer:
Salt and diamond are examples of crystalline solids, which have a regular, repeating molecular structure forming a three-dimensional lattice. Amorphous solids, on the other hand, do not exhibit this long-range order, with examples including glass and many plastics.
Step-by-step explanation:
Solids like salt and diamond have regular repeating molecular shapes and are called crystalline solids.
These solids have their constituent particles arranged in a regular, three-dimensional array called a lattice.
This contrasts with amorphous solids, which lack this long-range order and are composed of molecules that do not have a regular and repeating arrangement.
For example, NaCl (salt) is composed of a regular array of alternating positive (Na+) and negative (Cl−) ions, forming its crystalline structure.
Diamond also has a well-defined crystalline structure, where each carbon atom is bonded to four other carbon atoms in a tetrahedral lattice.
The regular pattern of crystalline solids can sometimes be seen macroscopically, and it's this orderly pattern that gives them their characteristic properties.