Question

Which of the following is a good conductor of electricity?
(A) Diamond
(B) Graphite
(C) Both A and B
(D) None of the above

Answer 1

Hint: Electricity is a free flow of electrons. If a structure of a compound consists of free electrons, it is said to be a good conductor of electricity. Both diamond and graphite are allotropes of carbon. Allotropes are compounds which are chemically the same but vary in their properties.

Complete step by step solution:
From the options given, we can see that both diamond and graphite are allotropes of carbon atoms. So, let us first discuss carbon.
-Carbon belongs to the second period and fourteenth group of the periodic table. It is a metalloid and has the highest self-linking property (i.e. catenation). Being the first member of its group, carbon is the smallest size atom and does not have d-orbitals. It also forms strong bonds with metals, nonmetals and metalloids.
-Diamond and graphite are large molecules of carbon that do not have a specific formula and they are considered as the allotropes of the carbon atom. Their size depends upon the extent of their physical structures. The structural difference in diamond and graphite leads to different physical as well as chemical properties.
-So, let us look at the differences between diamond and graphite, which will further give an idea about their conductivity:

DIAMOND	GRAPHITE
1. The hybridisation of carbon here is $s{{p}^{3}}$. Therefore, it has a tetrahedral structure and is a crystal structure. All four valencies of carbon atoms are satisfied.	1. The hybridisation of carbon is $s{{p}^{2}}$. The structure is trigonal planar. The planes in graphite slip one over another without forming any strong bonding between them. Only three valencies of carbon are filled.
2. It behaves as an insulator because there are no free electrons present in its three-dimensional structure for the conduction of electricity.	2. It can easily conduct electricity because it has one free electron per $s{{p}^{2}}$hybridised carbon

Thus, we can see that graphite is a good conductor of electricity.

Hence, the correct option is (B).

Note: Diamond and graphite have different physical properties but the same chemical properties as they are composed of the same element. Carbon has many allotropes and forms. The electrical conductivity of each of them is dependent upon the number of free electrons it has. One of its allotropes, Buckminster fullerenes is a good conductor of electricity and graphene is also a good conductor of electricity.