Question

How many atoms are present in a face centred cubic unit cell?

Answer 1

The cubic crystal system is a crystal system with a unit cell in the shape of a cube in crystallography. This is one of the most frequent and straightforward crystal and mineral shapes. There are three main varieties of these crystals: Primitive cubic or simple cubic, Body-centred cubic, Face-centred cubic.

Complete answer:
A form of atom arrangement found in nature is known as face-centred cubic (FCC or cF). A face-centred cubic unit cell structure is made up of atoms arranged in a cube with a fraction of an atom in each corner and six additional whole atoms in the middle of each cube face.
Eight other unit cells share the atoms in the corner of the cube. As a result, each corner atom is one-eighth of an atom in size.
Because the atoms on the unit cell's faces are shared with neighbouring unit cells, each face atom represents half an atom.
Using this notion, the FCC unit cell structure has a total of four atoms: six halves on each face and eight one-eighth atoms at the corners. (4 atoms) = (1/2 atoms x 6 faces) + (1/8 atoms x 8 corners)
The face-centred cubic (fcc) has a coordination number of 12 and a unit cell size of 4 atoms.

Note:
The atoms in the FCC unit cell arrangement are packed closer together than in other cell configurations (such as the simple unit cell arrangement, the body-centred cubic (BCC)). FCC metals are often softer and more ductile than their BCC counterparts due to their packing arrangement, which may be an essential consideration when selecting materials for a certain application.