Allotropes of Carbon:
Carbon occurs in nature in a free state as well as combined state.
Carbon occurs in nature in free state in forms:
These are also known as Allotropes of Carbon.
In the combined state , it occurs in the form of compounds like Carbon dioxide (CO2), Carbonates (limestone, marble and chalk), fossil fuels, organic compounds like nutrients, and things like wood, wool, cotton, etc.
What are allotropes:
Allotropes are different physical forms in which an element can exist.
Elements like Carbon , Silicon , Phosphorus and Sulfur have allotropes.
Examples of Allotropes:
- Diamond , graphite and Buckminsterfullerene are allotropes of carbon
- Phosphorus has white and red phosphorus as its allotropes
Different Allotropes of Carbon:
There are 3 Allotropes of Carbon:
- Fullerene (also called Buckminsterfullerene)
Lets learn about these in detail:
3D STRUCTURE OF A DIAMOND
- Diamond is a colorless , transparent solid having extraordinary shine .
- Diamond is the hardest natural substance known.
- In Diamond, each carbon atom is bound to 4 other carbon atoms by very strong covalent bonds .It hence also has a very high melting point .
- The rigid structure of diamond lends it its hardness.
- It forms a rigid, non planar 3-dimensional structure as shown below:
- Since it is shiny, it is used to make jewelry .
- It is extremely hard, and is used to make cutting instruments like glass cutting machines, saws etc.
- Sharp edged diamonds are used by eye surgeons to remove cataract from the eye.
- It is a grayish black , opaque substance which is soft and slippery to touch.
- In graphite, each carbon atom is bound to 3 other carbon atoms in the same plane .
- This gives hexagonal structure or array to graphite as shown below:-
- Each layer is far apart from the rest and hence only weak van der waals forces exist between the layers.
- The layers slide over each other which lends graphite its softness .
- This makes Graphite a good dry lubricant.
- Also, we know that a carbon atom has 4 valence electrons . In graphite, only 3 are used to make bonds with other atoms.
- One electron is free to move .
- This electron from each C atom in Graphite is called a Free electron . Free electrons make graphite a good conductor of electricity.
- Since it is soft and slippery, it is used to make lubricants for machine parts
- It is also used to make electrodes for dry cells because it is a good conductor of electricity.
- It is also used to make pencils and black paints .
- It is a newly discovered allotrope of carbon.
- In this case, carbon atoms are arranged in the form of a football . The shape is called a geodesic dome.
- Since it looks like a Geodesic dome designed by US Architect Buckminster Fuller , It was named after him as Buckminsterfullerene or it is simply known as Fullerene .
- It is a dark solid substance.
- Unlike diamond and graphite, It is a very small molecule that is made of only 60 Carbon atoms.
- Since it has 60 carbon atoms joined together, it is also called C 60 .