First 201 words of the document:
Arenes (aromatic hydrocarbons)
Long-term exposure may cause certain types of cancer.
Used as feedstock for production of many chemicals.
o Sooty flame
o Due to high carbon to hydrogen ratio.
Ring of carbon atoms.
Alternating single and double bonds.
Later adaption states that benzene molecule existed as two isomers that
it flipped between (switching over double and single bonds).
Explains many of the Doesn't explain data from
properties of benzene. experiments about:
o Bond length
o Reaction with bromine
Representation of benzene:
Each carbon forms three sigma-bonds (2 carbon and 1 hydrogen).
Leaving one p-orbital on each carbon, which is perpendicular to the
plane of the ring creating pi-bonds.
Each p-orbital contains a single electron that can move through the
whole pi-system (delocalised).
The delocalisation gives benzene extra stability electrons repel each
other, so a system where they're as far apart from one another as
possible will involve minimum repulsion and will therefore be
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The Delocalised Model of Benzene
The molecular formula of benzene is C6H6.
The delocalised model suggests that each carbon forms three sigma-bonds.
Therefore, there's one p-orbital on each carbon that is perpendicular to the
plane of the ring, which created pi-bonds. A pi-system is created from the
overlapping of p-orbitals and so the delocalisation is extended over all six
There're many pieces of evidence that support this model.…read more