Question

For a crystal of diamond, state the coordination number of each carbon atom?

Answer 1

Hint: The coordination number of a compound is the number of atoms, molecules, or ions that are present to the surrounding of a central atom in a complex structure or crystal structure. In diamonds, the atoms are arranged in a crystal structure which is also called a diamond cubic structure. By using this information one can develop the approach towards the solution of the given question.

Complete step by step answer:
1) The coordination number of an atom or molecule is also called a ligancy of that atom or molecule. It can be defined as the number of atoms or molecules or ions bonded to it which are present surrounding the central atom. The atom or molecule or ion surrounding the central atom or molecule or ion is called a ligand.
2) In the crystal structure of the diamond, the carbon atoms present in it are connected by the directional covalent bonds formed with each other between carbon atoms.
3) The one carbon atom in the structure forms four covalent bonds with the other four carbon atoms that acquire the four corners of the crystal structure which is cubic and shows the tetrahedral arrangement of atoms in the crystal structure.
4) In the diamond lattice, which is an ordered arrangement of points which describes the arrangement of particles that form a crystal, has four atoms which are present nearest to the central carbon atom with which it forms a covalent bond. The valency of the carbon atom is four hence, it forms a maximum of four covalent bonds.
5) Therefore, the coordination number of each carbon in a diamond crystal is four.

Note:
The diamond is an allotrope of carbon. An allotrope is a phenomenon where an atom or element can exist in two or more physical forms. This means the diamond is nothing but a full arrangement of carbon atoms in its crystal structure. Graphite is also another example of an allotrope of carbon.