Final answer:
Cycloheptatriene can become aromatic through the formation of a tropylium ion, which has a six-membered ring with fully delocalized six π-electrons and exhibits stability due to its aromatic character.
Step-by-step explanation:
To make cycloheptatriene aromatic, a molecular transformation must occur that allows the molecule to follow Huckel's rule for aromaticity which requires that the molecule must have a ring with alternating double bonds, be planar, and contain a total number of (4n+2) π-electrons. For the seven-membered cycloheptatriene, this is achieved by forming a six-membered ring, known as a benzene ring, through the loss of a hydrogen atom and forming a stable, positive ion known as the tropylium ion. This ion is aromatic because it now contains a fully delocalized set of six π-electrons (complying with 4n+2, where n=1) over a planar, six-membered carbon ring structure. Tropylium ions are known for their remarkable stability due to the aromatic character imparted by electron delocalization.