Tag: chemistry

Carbon shows the property of catenation as it is small in size and has the ability to form stable covalent bonds with other carbon atoms to form a chain-like structure. The bond energy between the C-C bond is very high which enables them to form a long chain of C-C stable bonds.

Carbon can form huge number of carbon compounds due to following properties: 

Catenation is  a self linkage property, present in carbon. Because of catenation, carbon can form long chains, branched chains and closed chains.

Tetravalence: It is the state of an atom with four electrons available for covalent chemical bonding in its valence 

Carbon is capable of forming many allotropes due to its valency.  
Sixty carbon atoms form the shape of a ball like a football with a carbon atom at each corner of the 20 hexagons and 12 pentagons. The buckminsterfullerenes, is also called fullerenes, Fullerenes are molecules of varying sizes composed entirely of carbon, which take the form of a hollow sphere, ellipsoid, or tube.
Option "C" is correct.

In diamond, each carbon atom is covalently bonded to four other carbon atoms. A lot of energy is needed to separate the atoms in diamond. 

In diamond, each carbon atom is covalently bonded to four other carbon atoms, leaving no free electrons available to conduct electricity.

Diamond is transparent, hard and poor conductor of electricity. In-fact, diamond is hardest known substance on earth. The hardness is due to the presence of strong covalent bonds between C atoms. Hence, the option (B) is the correct answer.

Graphite is an allotrope of carbon. Each carbon is covalently bobded to other three carbon atoms, it contains layers of carbon. The layers slid over each other easily because of the weak Van der Walls' forces between them.

Fullerene is an allotrope of carbon in the form of hollow sphere and called as buckyballs. $C-60$ is the crystalline form and is used as semiconductor.

Crystal density of graphite is $2.266 g/cm^3$ as compared with $3.53 g/cm^3$ for diamond.
In the graphite structure, only three of the four valence electrons of carbon form regular covalent bonds with adjacent carbon atoms.

C-60 is the most stable form and it led the scientists to the conclusion that the cluster must be a spheroidal closed cage in the form of icosahedron.