Question

Why is Diamond so strong?

Answer 1

The strength of any compound or substance is due to its intermolecular structure. The intermolecular structure of diamond is so rigid and stable that it becomes the hardest and strongest element on earth. This strength of diamond is due the bond formation of the constituents atoms which is so stable which makes its strength.

Complete answer:
Diamond is one of the allotropes of the carbon family. The other one is graphite which is soft and brittle in comparison to diamond. The constituent atom of diamond is carbon atom and those carbon atoms are joined to each other through the covalent bond. These atoms form a stable structure that it is hard to break any of the bonds they formed. They form a rigid tetrahedral structure which is stable in nature. The heat and the pressure also makes the atoms come close to each other and thus forms a rigid stable structure. Also it has a very high melting point. Due to its solid structure it becomes hard to break these carbon bonds. It is insoluble in water and in any organic solvents. While graphite has a free electron it does not have a free electron. Hence it doesn't conduct electricity.

Note:
The strength of the diamond is due to its three dimensional structure which provides it strength. The pressure and temperature at which it is found also favors its strength. The tetrahedron structure is the most stable structure and it cannot be easily broken. All the valence electrons of carbon are involved in bond making in the structure. There is no free electron like graphite.