Question

What is true about simple cubic type of unit cells?

• A. Eight constituents are at different corners of the cube.
• B. The number of atoms per unit cell is $1$.
• C. Contribution by an atom at one corner is $\frac{1}{8}$th of an atom.
• D. None of the above.

Answer 1

Answer: (A), (B), (C)

The correct options are
A Eight constituents are at different corners of the cube.
B The number of atoms per unit cell is $1$.
C Contribution by an atom at one corner is $\frac{1}{8}$th of an atom.

Simple/Primitive/Basic unit cell : A unit cell having lattice point only at corners is called as primitive or simple unit cell In this case, there is one atom at each of the eight corners of the unit cell considering an atom at one corner as the centre, it will be found that this atom is surrounded by six equidistant neighbours (atoms) and thus, the co-ordination number will be six. If 'a' is the side of the unit cell, then the distance between the nearest neighbours shall be equal to 'a'.