Which term describes the regular arrangement of atoms in a crystalline solid?

The term that describes the regular arrangement of atoms in a crystalline solid is "lattice." In crystallography, a lattice is a three-dimensional arrangement of points (representing the positions of atoms, ions, or molecules) that extends infinitely in space. Each point in the lattice corresponds to a position occupied by an atom in the crystal structure, and the specific geometric arrangement of the lattice determines many of the material's properties, such as conductivity, hardness, and symmetry.

A lattice is characterized by its repeating patterns, which provide a systematic way to represent the structure of the solid. This concept is essential in understanding how atoms bond and interact within materials, especially in relation to phenomena like diffraction patterns observed in X-ray crystallography.

In contrast, other terms like "matrix," "structure," and "framework" do not specifically refer to the atomic arrangement in a crystalline solid. A matrix generally refers to a surrounding medium in which something is embedded, while structure could denote the overall arrangement or organization of various components, not limited to atomic arrangement. Framework, while it may imply a structured arrangement, lacks the specific emphasis on the long-range periodic order characteristic of a lattice.