Properties of Graphite and Diamond

Graphite and diamond are two allotropes of carbon that have very different physical and chemical properties. Let's take a look at each of the given statements and determine if they are correct.

B) Graphite has higher electrical conductivity than diamond.

This statement is correct. Graphite has a higher electrical conductivity than diamond because of its unique structure. In graphite, carbon atoms are arranged in layers that are held together by weak van der Waals forces. Within each layer, the carbon atoms are bonded together in a hexagonal lattice. Each carbon atom in the layer has three covalent bonds with neighboring atoms, leaving one electron free to move through the lattice. This makes graphite a good conductor of electricity along the plane of the layers.

Diamond, on the other hand, has a tightly packed, three-dimensional structure in which each carbon atom is bonded to four neighboring atoms in a tetrahedral arrangement. This leaves no free electrons to conduct electricity, so diamond is an insulator.

D) Graphite has higher C-C bond order than diamond.

This statement is also correct. A bond order is the number of chemical bonds between a pair of atoms. In graphite, each carbon atom is bonded to three neighboring carbon atoms, resulting in a bond order of 1.33. In diamond, each carbon atom is bonded to four neighboring carbon atoms, resulting in a bond order of 1.

This means that the carbon-carbon bonds in graphite are stronger than those in diamond, despite the fact that graphite is a softer material than diamond. This is because the layers in graphite can easily slide past each other, whereas the tightly packed atoms in diamond make it extremely hard.

A) Graphite is harder than diamond.

This statement is incorrect. Diamond is the hardest known natural material, with a rating of 10 on the Mohs scale of mineral hardness. Graphite, on the other hand, has a rating of 1-2 on the Mohs scale, making it a very soft material.

C) Graphite has higher thermal conductivity than diamond.

This statement is incorrect. Diamond has the highest thermal conductivity of any known material, making it an excellent heat conductor. Graphite, while a good electrical conductor, is a poor heat conductor in the plane of its layers.

Higher electrical conductivity of graphite is due to the presence of free electrons which are not available in diamond. the free electrons impart partial 2× bond character to C–C bond