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Lewis structure

Lewis structure of benzene

30 valence electrons. One C-C single bond and one C-H single bond, with no lone pair on C. 2 resonance structures.

HHCHCCCCHCHH
  • C
  • H

C₆H₆Benzene

Trigonal planar

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

  • Hybridisationsp²
  • Bond angle120°
  • Polaritynon-polar

Lewis structure

30 valence electrons, 2 resonance structures
i

The two Kekule structures; the real ring has six equal C-C bonds.

CCCCCCHHHHHH
CCCCCCHHHHHH

Formal charges: none

Why this shape

  1. Each C has 4 valence electrons. It uses four in one single bond to C, one double bond to C and one single bond to H, so none are left over.
  2. Steric number = three sigma bonds + no lone pairs = 3, so each C is sp² hybridised. A double or triple bond counts once: only its sigma bond uses a hybrid orbital.
  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. All the bond pairs repel each other equally, so the angle is the ideal 120°.
  5. The flat ring is symmetric, so the C-H bond dipoles cancel.
Working

How to draw it

  1. Count the valence electrons: 6 × C 4 + 6 × H 1 = 30 valence electrons, 15 pairs.
  2. Join the atoms with single bonds: the C atoms to each other and the H atoms around them.
  3. Give each outer atom lone pairs until it has an octet (H needs only two electrons), then put any electrons left over on the central atom.
  4. Where an atom is still short of an octet, turn a lone pair of its neighbour into a shared pair: that makes a double or triple bond.
  5. Result: one C-C single bond and one C-H single bond, with no lone pair on C.
  6. Formal charge = valence electrons − lone pair electrons − number of bonds. Here: none.
  7. The double bonds can be placed in two equivalent ways, so there are two resonance structures. The real molecule is a hybrid of them.

Class 11, Chapter 4 Chemical Bonding and Molecular Structure.

Questions

Lewis structure of C6H6: quick answers

How many valence electrons are in C6H6?

6 × C 4 + 6 × H 1 = 30 valence electrons, 15 pairs.

What are the formal charges in the Lewis structure of C6H6?

Every atom has a formal charge of zero.

How many resonance structures does C6H6 have?

2. The double bonds can be placed in two equivalent ways, so there are two resonance structures. The real molecule is a hybrid of them.

Try any molecule