C6H6 Lewis Structure
Benzene · The parent aromatic hydrocarbon, and a known carcinogen.
The C6H6 Lewis structure has 30 valence electrons, drawn as three C–C bonds, three C=C bonds and six bonds to hydrogen, with zero lone pairs in total. The central C is sp2 hybridized, which makes it a trigonal planar molecule with a bond angle of 120 degrees. C6H6 is nonpolar: the bond dipoles and lone pairs are arranged symmetrically, so the vectors cancel and the molecule has no net dipole. There are two equivalent resonance structures.
- 30 valence e−
- trigonal planar
- 120° bond angle
- sp2
- nonpolar
Calculated properties
| Total valence electrons | 30 |
|---|---|
| Bonding electrons | 30 (15 shared pairs) |
| Nonbonding electrons | 0 (0 lone pairs) |
| Lone pairs on C | 0 |
| Electron domains (steric number) | 3 |
| VSEPR notation | AX3 |
| Electron geometry | trigonal planar |
| Molecular geometry | trigonal planar |
| Bond angle | 120° |
| Hybridization | sp2 |
| Polarity | nonpolar |
| Formal charges | all zero |
| Resonance structures | 2 |
| Molar mass | 78.114 g/mol |
How to draw the C6H6 Lewis structure
Step through it. The bar shows how much of the 30-electron budget is spent at each stage - it never grows, which is the whole constraint.
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Skeleton. Join every connected pair with one bond. 12 bonds spends 24 electrons.
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Outer octets. Spend electrons as lone pairs on the outer atoms. That uses the entire budget, and the central atom has nothing left over.
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Multiple bonds. The central atom is still short of an octet, so three lone pairs on the outer atoms move in to be shared. The electron count does not change - the same electrons are just counted by both atoms now.
The reasoning at each step
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Count the valence electrons
Add up the outer-shell electrons every atom brings. That total is the budget for the whole structure - every line and every dot has to come out of it, and nothing may be added.
6 x 4 (C) + 6 x 1 (H) = 30 valence electrons -
Work out what is bonded to what
Benzene is a six-carbon ring. Four degrees of unsaturation in C6H6 means one ring plus three pi bonds.
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Join everything with single bonds first
Every connection starts as one shared pair. Draw them all before worrying about double bonds - the arithmetic in the next step is what tells you where the double bonds have to go.
12 bonds x 2 = 24 electrons used, 6 left -
Work out how far short you are
Add up what every atom still needs to fill its shell - eight electrons for most atoms, two for hydrogen - minus what its single bonds already give it. Compare that with the electrons you have left. The difference decides everything that follows.
needs 12, has 6, short by 6 -
Turn the shortfall into multiple bonds
Being short means atoms have to share more. Every pair that moves from a lone pair into a bond counts twice - once for each atom - so a shortfall of 6 is covered by 3 extra shared pairs. That is where the double bonds come from.
C2=C3, C4=C5, C6=C1 -
Check the formal charges
Formal charge is valence electrons, minus lone-pair electrons, minus the number of bonds. Every atom here comes out at zero, which is the sign of a good structure.
all formal charges = 0 -
Work out the shape
Count the electron domains on C: 3 bonded groups. A double or triple bond still counts as one domain, because it points in one direction. That gives trigonal planar electron geometry; ignore the lone pairs and the atoms themselves sit in a trigonal planar arrangement.
steric number 3 -> sp2 -> trigonal planar, bond angle 120 -
Decide whether it is polar
The bond dipoles and lone pairs are arranged symmetrically, so the vectors cancel and the molecule has no net dipole.
dipoles cancel -> nonpolar
Resonance structures
More than one drawing gives the same electron count and the same formal charges, and no single one of them is the real molecule. C6H6 is an average of the 2 structures below, which is why bonds that look different here are actually identical in the real molecule.
Is C6H6 polar or nonpolar?
C6H6 is nonpolar. The bond dipoles and lone pairs are arranged symmetrically, so the vectors cancel and the molecule has no net dipole.
| Bond | Electronegativity difference | Character |
|---|---|---|
| C–H | 0.35 | nonpolar covalent |
| C–C | 0.00 | nonpolar covalent |
Common questions
How many valence electrons does C6H6 have?
C6H6 has 30 valence electrons. 30 of them are in bonds and 0 sit in lone pairs.
What is the molecular geometry of C6H6?
C6H6 is a trigonal planar molecule. The central C has 3 bonded groups, a steric number of 3, which gives trigonal planar electron geometry and a trigonal planar molecule.
What is the bond angle in C6H6?
The bond angle in C6H6 is 120 degrees. That is the ideal trigonal planar angle, and nothing distorts it here.
What is the hybridization of C6H6?
The central C in C6H6 is sp2 hybridized. Steric number 3 means 3 orbitals have to be mixed, which is exactly what sp2 gives you.
Is C6H6 polar or nonpolar?
C6H6 is nonpolar. The bond dipoles and lone pairs are arranged symmetrically, so the vectors cancel and the molecule has no net dipole.
Does C6H6 have resonance structures?
Yes. C6H6 has two equivalent resonance structures. The real molecule is not any one of them - it is an average, so every bond that differs between the drawings is really the same length in the actual molecule.