11.25 What are allotropes? Sketch the structure of two allotropes of carbon namely diamond and graphite. What is the impact of structure on physical properties of two allotropes?
The various forms of the same element are known as allotropes. They have the same chemical properties but different physical properties.
Allotropes of carbon -
In diamond, all the carbon is hybridised and each of the carbon is attached with the four neighbour carbon atom. by a strong covalent bond. This provides it with a very rigid structure and makes it the hardest substance.
In Graphite, carbon is hybridised and attached with three neighbours carbon. It has a layered structure, which is attached with the weak van der Waal forces. These layers can slide over one another so that's why they are soft and used as a lubricant.