Question 1

Is benzene the same as cyclohexa-1,3,5-triene?

Accepted Answer

No. Cyclohexa-1,3,5-triene is a hypothetical molecule with alternating, distinct single and double bonds of different lengths. Benzene is a real molecule where all C-C bonds are identical in length and strength due to a delocalised π system, which makes it significantly more stable.

Question 2

Why is the bond angle in benzene exactly 120°?

Accepted Answer

Each carbon atom is sp² hybridised, forming three σ bonds. According to VSEPR theory, three regions of electron density around a central atom will arrange themselves to be as far apart as possible, resulting in a trigonal planar geometry with 120° bond angles.

Question 3

If benzene is so stable, why does it react at all?

Accepted Answer

While the aromatic ring is very stable, the delocalised π system is a region of high electron density. This makes it susceptible to attack by strong electrophiles (electron-seeking species). The reactions proceed via a substitution mechanism that allows the stable aromatic ring to be regenerated in the final product.

Question 4

What does the circle inside the hexagon represent when drawing benzene?

Accepted Answer

The circle represents the six delocalised π electrons that are shared equally among all six carbon atoms in the ring. It is a more accurate representation of benzene's bonding than the Kekulé structure with alternating double bonds.

Shapes of aromatic organic molecules; σ and π bonds

What you need to know

Benzene's Stable Secret