Question

What makes graphite a good conductor of electricity?

• A. Presence of strong covalent bonds
• B. Free electrons in its layered structure
• C. Its rigid three-dimensional structure
• D. Its slippery texture

Hint:

Contrast the structure and bonding in graphite with that in diamond. Diamond has a three-dimensional network of strong covalent bonds with no free electrons, making it a poor conductor of electricity.

Answer 1

The Correct Option is B

Step 1: Understand the structure of graphite.
Graphite is an allotrope of carbon. In graphite, each carbon atom is bonded to three other carbon atoms in a hexagonal planar structure, forming layers. These layers are held together by weak van der Waals forces.
Step 2: Consider the bonding in graphite.
Each carbon atom in graphite uses three of its four valence electrons to form strong covalent bonds with three neighbouring carbon atoms in the same layer. This leaves one valence electron per carbon atom free.
Step 3: Explain how free electrons contribute to electrical conductivity.
Electrical conductivity occurs due to the movement of charged particles, typically electrons. The free electrons in graphite are delocalized and can move freely within each layer. These mobile electrons can carry an electric current when a voltage is applied, making graphite a good conductor of electricity.
Step 4: Analyze the given options.

1. 
   Presence of strong covalent bonds:
   Strong covalent bonds hold the carbon atoms within each layer, providing structural stability, but they do not directly contribute to electrical conductivity. In fact, the electrons involved in these bonds are not free to move and carry charge.
2. 
   Free electrons in its layered structure:
   As explained above, the presence of delocalized or free electrons within each layer of graphite is responsible for its good electrical conductivity.
3. 
   Its rigid three-dimensional structure:
   Graphite does not have a rigid three-dimensional structure. It has a layered structure where the layers can slide over each other, which accounts for its softness and slippery texture. A rigid three-dimensional network structure, like that of diamond, typically results in poor electrical conductivity due to the absence of free electrons.
4. 
   Its slippery texture:
   The slippery texture of graphite is due to the weak van der Waals forces between the layers, allowing them to slide easily. This property is related to its structure but not directly to its electrical conductivity.

Therefore, graphite is a good conductor of electricity due to the presence of free electrons in its layered structure.