Characteristics of crystal lattice:

• Each of the constituent particles in a crystal lattice is shown by a single dot.
• Those single dots are called the lattice site .
• In a crystal lattice, the lattice points are together joined by straight lines.
• Straight lines are used to join a crystal lattice together.
• Joining lattice points with the help of straight lines forms crystal lattice’s geometry.

Unit cell:

The unit cell is the smallest and simplest shape from which an entire structure can be made of.

Unit Cell: Unit Cell is the smallest part of the crystal lattice. The unit cell produces the whole lattice by the repetitive process in different spaces.

Parameters of a unit cell:

One unit cell is explained by six parameters. 

There are three edges, that is, a, b, c and the angles between them are named as α, β and γ.

Dimensions of the unit cell are represented by a, b and c.

They may or may not be mutually perpendicular.

The angle between edges b and c, c and a, a and b is represented by “α”, “β”, “γ” respectively.

Types of Unit Cell:

Basically, two-unit cells are present known as, the Centred and Primitive Unit Cells

Primitive Unit Cells: When unit cells’ particles find themselves on the corners solely, then it’s remarked as the primitive unit cells.

Centred Unit Cells: When these unit cell  particles are placed at totally different positions, likewise to those present at the unit cell’s corner, then it’s remarked as the Centred building block.

There are unit 3 varieties of Centred building block

Body Centred Unit Cells

Face-Centred Unit Cells

End-Centred building block

In general, seven varieties of unit cells are formed. They take the form of the Cubic, Hexagonal, Tetragonal, Monoclinic, Orthorhombic, Trigonal or Rhombohedral or Triclinic.

A common formula that is bestowed for N counting, from the arguments and also the ‘n’ number of ions or atoms present in a unit cell is given by:

N=Nbody + Nface2 + Nedge4 + Ncorner8