Summary:
- A crystal is a substance in which the particles are arranged in an orderly, repeating, three-dimensional pattern.
- Different arrangements of the particles within a crystal cause them to adopt several different shapes.
- A crystal is defined by its faces, which intersect with one another at specific angles, which are characteristic of the given substance.
- Each of the seven crystal systems differs in terms of the angles between the faces and in the number of edges of equal length on each face.
- The seven crystal system are shown below, along with an example of each.