Question 4: Define unit cell, basis and space lattice.
- Unit cell: It is the smallest geometric figure whose repetition gives the actual crystal structure. It is the smallest group of atoms (or molecules or ions) which is the representative of the whole crystal structure.
- Basis: A single atom or a group of same or different kinds of atoms is associated with each lattice point which is called basis.
- Space lattice: In a crystalline solid, atoms or molecules are periodically arranged in three dimensions. If such units of atoms or molecules are replaced by points in space the resultant points of space is called space lattice.