A regular spacing or arrangement of atoms in a crystalline material is called

A regular spacing or arrangement of atoms in a crystalline material is called a lattice. A lattice refers to a repeating pattern of atoms, ions or molecules in a solid material. In other words, it is a highly ordered and structured arrangement of particles in a solid crystal. Each particle in the crystal is surrounded by its neighboring particles, and the particles are arranged in a highly specific pattern that is repeated throughout the crystal. The lattice structure of a material has important effects on its physical and chemical properties. For example, it can affect a material's strength, hardness, and electrical conductivity. Understanding the lattice structure of a material is also important in many scientific fields, including materials science, condensed matter physics, and crystallography.