NCl3 Resonance Structures and Lewis StructureExplained Step-by-Step

Benzene is a colorless, volatile, highly flammable liquid that is a useful solvent used extensively in the chemical industry.

Resonance structures

Benzene, C6H6, has two equally valid Lewis structures. Both have three C-C and three C=C, with all C and H atoms neutral and where each C is attached to one H and two C atoms.

The difference is which C atoms are attached by C-C and C=C (to help understand this, try numbering the C atoms 1 to 6, starting with number 1 at the top and going around to the right). These Lewis structures (the resonance contributors) each show single bonds and double bonds which would imply that there should be two difference bond lengths present in a molecule of benzene. However, that is not the case. The experimentally measured values show that there is one bond length of about 139 pm.

Step-by-Step Drawing the lewis structure of C6H6

Step 1: Calculate the total number of valence electrons

Each carbon atom contributes 4 valence electrons, and each hydrogen atom contributes 1, giving a total of 6 x 4 + 6 x 1 = 30 valence electrons.

Step 2: Determine the central atom

Carbon (C) is the central atom in benzene because it is the primary element in the molecule.

Step 3: Draw covalent bonds (shared electrons)

Connect each carbon atom to the next with a single bond (line) and distribute the remaining electrons as lone pairs around each carbon atom. Each hydrogen atom will be attached to a carbon atom with a single bond.

Step 4: Assign lone pairs of electrons (satisfying the octet rule)

Ensure each carbon atom has 8 electrons (2 lone pairs and 2 bonding pairs), and each hydrogen atom has 2 electrons (1 lone pair and 1 bonding pair).

Step 5: Check stability

Formal charges may not be necessary as all atoms have achieved the octet rule. However, the alternating single and double bonds in benzene result in resonance structures, indicating delocalized π electrons.