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Hybridisation

Hybridisation of carbon in graphite

Each C atom is sp² hybridised (hybridization by the VSEPR count): 3 sigma bonds and no lone pairs give a trigonal planar shape, bond angle 120°.

CCCCCCCCCCCCC
  • C

CGraphite

Trigonal planar

AB₃: 3 bond pairs, no lone pairs on each C

  • Hybridisationsp²
  • Bond angle120°
  • Polaritynon-polar

Why this shape

  1. Each C has 4 valence electrons and is bonded to three other C atoms.
  2. Steric number = three sigma bonds + no lone pairs = 3, so each C is sp² hybridised.
  3. Three electron pairs point to the corners of a flat triangle (trigonal planar electron geometry). With no lone pairs the atoms take the same shape: trigonal planar.
  4. Each C uses three sp2 orbitals for three C-C sigma bonds in a flat sheet of hexagons, 120 degrees apart. The fourth electron of each C is in a pi system spread over the whole sheet, which is why graphite conducts.
  5. Every bond joins two C atoms, so no bond is polar.
Working

Why this hybridisation and shape

  1. Each C has 4 valence electrons and is bonded to three other C atoms.
  2. Steric number = three sigma bonds + no lone pairs = 3, so each C is sp² hybridised.
  3. Three electron pairs point to the corners of a flat triangle (trigonal planar electron geometry). With no lone pairs the atoms take the same shape: trigonal planar.
  4. Each C uses three sp2 orbitals for three C-C sigma bonds in a flat sheet of hexagons, 120 degrees apart. The fourth electron of each C is in a pi system spread over the whole sheet, which is why graphite conducts.
  5. Every bond joins two C atoms, so no bond is polar.

Class 11, Chapter 4 Chemical Bonding and Molecular Structure.

Questions

Hybridisation of C: quick answers

What is the hybridisation of C?

Each C has 4 valence electrons and is bonded to three other C atoms. Steric number = three sigma bonds + no lone pairs = 3, so each C is sp² hybridised.

What is the shape of C and its bond angle?

Trigonal planar, with a bond angle of 120 degrees. Three electron pairs point to the corners of a flat triangle (trigonal planar electron geometry). With no lone pairs the atoms take the same shape: trigonal planar. Each C uses three sp2 orbitals for three C-C sigma bonds in a flat sheet of hexagons, 120 degrees apart. The fourth electron of each C is in a pi system spread over the whole sheet, which is why graphite conducts.

Is C polar or non-polar?

Non-polar. Every bond joins two C atoms, so no bond is polar.

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