Question

Define allotropy. Name the various allotropes of carbon.

Answer 1

Hint: The concept of existence of any chemical element in the different physical forms gives the correct answer to the above question. The basic definition of allotropy includes this fact and the forms of allotropes of carbon are based on the arrangement of atoms in the structure of that substance.

Complete step by step answer:
In the lower classes of inorganic chemistry, we have studied about the elements that exist in various forms and also how they differ in the properties.
We shall now refresh those terms and define what allotropy is and also deduce the various allotropic forms of carbon.
- Carbon makes only about $0.025$ percent of the Earth’s crust and its abundance ranks nineteenth in the order of the elemental abundance.
- Allotropy or allotropism is nothing but the property of some of the chemical elements that can exist in two or more different forms but in the same physical state.
Thus, according to chemistry, Allotropy can be defined as ‘The existence of an element in two or more forms which can differ in the arrangement of atoms in crystalline solids but occurs in the same physical state is called allotrope and the phenomenon is called allotropy’.
- Carbon can form many allotropes and their physical characteristics vary accordingly.
- The two main allotropes of carbon are diamond and graphite.

Note: Carbon has the capability to form many allotropes because of its valency and among these, diamond and graphite are the main forms and the others include the large – scale structures that are nanotubes, nanotubes and nanoribbons. Fullerene is also an allotrope of carbon.