What is the term that defines the smallest piece of a crystal that shows the shape of that type of crystal?

The correct answer to this open question is the following.

The term that defines the smallest piece of a crystal that shows the shape of that type of crystal is "unit cell."

In the atomic world, the smallest portion of a crystal lattice is a unite cell. A unit cell shows the 3D or three-dimensional pattern of the crystal. So this unite cell can repeat itself to form the crystal lattice. There are cubic cells, monoclinic cells, tetragonal cells, orthorhombic, cells, and rhombohedral cells.

- aluminum and copper chloride.

- the chloride ion to separate the aluminum from the oxygen so that the aluminum can react with the copper ions (and the water molecules).

the answer would be a