Q.
1. How will you distinguish between :-
(i) Crystal lattice and Unit cell.
(ii) Tetrahedral void and Octahedral void.
Answers
Explanation:
(i) Crystal lattice
The crystal lattice is the symmetrical three-dimensional structural arrangements of atoms, ions or molecules (constituent particle) inside a crystalline solid as points. It can be defined as the geometrical arrangement of the atoms, ions or molecules of the crystalline solid as points in space.
Unit cell
Unit Cell is the smallest part (portion) of a crystal lattice. It is the simplest repeating unit in a crystal structure. The entire lattice is generated by the repetition of the unit cell in different directions
(ii) Tetrahedral void
Now there are two types of three-dimensional close packing in crystals. One such type is Cubic Close packing. Here the two-dimensional structures are stacked in a specific alignment. The layers alternate with each other. So the second layer will be located in the depression of the first layer.
You will notice that a triangle-shaped void is seen in this type of alignment. The sphere which is in the depression will leave a void between itself and the sphere in the layer above. This void is the Tetrahedral Void.
Octahedral void
If you observe a three-dimensional structure of a crystal lattice you will observe the gaps in between the spheres. These are the voids. As you see that tetrahedral voids are triangular in shape. When two such voids combine, from two different layers they form an octahedral void.