What type of structure does a crystalline substance have if atoms are located in the corners of the cube and one on the center of each face?

A crystalline substance that has atoms located at the corners of a cube and one atom at the center of each face is characteristic of a face-centered cubic (FCC) structure, which is a type of cubic structure. In this arrangement, there are lattice points at each corner of the cube as well as at the center of each face, creating a highly symmetrical and densely packed configuration.

This structure is notable for its high packing efficiency, which allows for maximum atomic density. The face-centered cubic lattice is often found in metals like copper, aluminum, and gold, where the arrangement contributes to the material's properties such as malleability and ductility.

In contrast, hexagonal, tetragonal, and monoclinic structures have different arrangements and symmetries, which do not match the specific geometry described in the question. Thus, the correct identification of the structure as a cubic one is essential in understanding the basic principles of crystallography.