Graphite has ______ hybridisation. 

CONCEPT:

Hybridisation in Graphite

• Hybridisation refers to the mixing of atomic orbitals to form new hybrid orbitals that can form covalent bonds.
• Graphite is a crystalline form of carbon where each carbon atom is bonded to three other carbon atoms in a planar hexagonal arrangement.
• The hybridisation of carbon atoms in graphite is sp².
• In sp² hybridisation:
  • One s orbital and two p orbitals mix to form three sp² hybridised orbitals.
  • The three hybrid orbitals lie in the same plane at an angle of 120°, forming a trigonal planar geometry.
  • The unhybridised p orbital is perpendicular to the plane and forms delocalised π bonds, giving graphite its characteristic electrical conductivity.

EXPLANATION:

• In graphite:
  • Each carbon atom forms three sigma (σ) bonds with neighboring carbon atoms using sp² hybridised orbitals.
  • The unhybridised p orbital of each carbon atom overlaps with the unhybridised p orbitals of adjacent carbon atoms, forming a delocalised π-electron system.
  • This delocalisation contributes to graphite’s good electrical conductivity and its layered structure.
• sp³ hybridisation (option 1) occurs in tetrahedral structures like diamond, not in graphite.
• sp hybridisation (option 3) is found in linear molecules like acetylene (C₂H₂).
• sp³ and sp hybridisation together (option 4) do not occur in graphite.

Therefore, the correct answer is option 2: sp² hybridisation.