Explain the terms space lattice and …

The smallest group of atoms or molecules, whose repetition at regular intervals in three dimensions produces a crystal, is called as a Unit cell. Hence, a unit cell is the smallest portion of a crystal lattice which, when repeated in different directions, generates the entire lattice. Each unit cell is defined in terms of lattice points – the points in space about which the particles are free to vibrate in a crystal.

The position of atoms, molecules, or ions in a solid crystal, relative to one other in space, is usually designated by points. Such a representation is called space lattice. Thus, we define the space lattice as an array of points showing how molecules, atoms or ions are arranged at different sites in three-dimensional spaces.