To determine the amorphous allotrope of carbon, we need to understand the different forms (allotropes) of carbon and their properties.
1. Understanding Allotropes of Carbon:
Allotropes are different structural forms of the same element. Carbon has several allotropes, each with distinct physical and chemical properties. The key allotropes of carbon are:
- Buckminsterfullerene (Cāā): A spherical molecule composed of 60 carbon atoms arranged in a hollow structure resembling a soccer ball. It is not amorphous; it has a well-defined crystalline structure.
- Graphite: A layered structure where carbon atoms are arranged in hexagonal layers. Graphite is crystalline but exhibits some amorphous-like behavior due to its layered arrangement and sliding planes.
- Coal: An impure form of carbon that is primarily composed of carbon but also contains other elements and compounds. Coal is considered an amorphous allotrope because it lacks a long-range ordered crystalline structure.
- Diamond: A highly ordered, three-dimensional crystalline structure where each carbon atom is covalently bonded to four other carbon atoms in a tetrahedral arrangement. Diamond is a crystalline allotrope.
2. Identifying the Amorphous Allotrope:
Among the given options, coal is the only allotrope of carbon that is classified as amorphous. This is because coal does not have a well-defined crystalline structure and is instead a mixture of various carbon forms along with impurities.
3. Conclusion:
The amorphous allotrope of carbon is coal.
Final Answer: