Why is diamond hard and graphite brittle while both are made up of carbon atoms?A. Difference in the melting pointB. Difference in the conductivityC. Difference in the nature of carbon bondsD. Difference in the boiling point

C. Difference in the nature of carbon bonds

The primary reason for the difference in properties between diamond and graphite, despite both being composed of carbon atoms, lies in the nature of their carbon bonds.

In diamond, each carbon atom forms four strong covalent bonds with other carbon atoms, creating a rigid three-dimensional structure known as a tetrahedral lattice. This arrangement results in a very strong and rigid structure, making diamond extremely hard.

In contrast, graphite consists of layers of carbon atoms arranged in a hexagonal lattice. Within each layer, the carbon atoms form strong covalent bonds, similar to those in diamond. However, the layers themselves are held together by weak van der Waals forces. These forces allow the layers to slide past each other easily, making graphite relatively soft and brittle.

Therefore, the difference in the nature of carbon bonds is the key factor contributing to the contrasting properties of diamond and graphite.