Organic Chemistry - V - Aromaticity

Conjugation is a molecule that has double bonds separated by single bonds causing a linking of adjacent p orbitals.

Besides being conjugated, the molecule must be in a planar configuration so that the p orbitals line up. The effect of resonance is a cloud of declocalized electrons, yielding a very stable molecule.

When the fully planar molecule, with overlapping p orbitals, is present in a ring, the term aromatic is applied. Benzene is the most commonly found aromatic, but many others exist that do not resemble benzene. The following three questions provide a guide to establishing whether or not a molecule is aromatic:
Are the atoms in a ring configuration (cyclic geometry)?
Are 4n+2 pi electrons present, where n = 0,1,2,3,etc. Huckel's rule?
Does each member of the ring have an sp^2 or sp hybridized configuration?

Electrophiles. It's because the molecule is electron rich, and the electron cloud is quite accessible.

Activators are electron-donating groups, they increase the rate of reaction, and are ortho,para directors.
Deactivators are electron-withdrawing groups, decrease the rate of reaction, and are meta directors.