Aromatic, Anti-aromatic and Non-aromatic

Aromatic, anti-aromatic and non-aromatic can be distinguished by 2 "sets" of rules. The first set of rules will separate aromatic and anti-aromatic compounds from non-aromatic; the second set of rules than can tell apart what the aromatic is from an anti-aromatic compound.

The first set of rules have 3 basic guidelines

1. It must have an uninterrupted cyclic cloud of pi electron on the plane of molecule.
2. Pi cloud must be cyclic and has a p orbital ( molecule must be cyclic)
3. The molecule must be planar.

Non-aromatic  ( even just break one of the 3 basic rules above)

Not Planar, Because it is big enough, it has a boat shape. 

Once you determine the compound sustain all three basic rules, now comes to the second sets of rules to determine if the compound is an aromatic or an anti-aromatic

Aromatic

4n+2= electrons in the pi clouds.

(a)

How many pi electrons?  It has 7 pairs... means 14 electrons.

When we calculate this, we use 4n+2= 14, n=3. It is an integer. So the compound is aromatic.

(b)

While thinking how many pi electron in this system, first to know is nitrogen has one invisible pair electrons. ( it usually does not draw out) When nitrogen bonds to 3 other bonds, it will have a lone pair. So in total, the pi electrons in this system is 3 pairs of electrons, 6 pi electrons.

4n+2=6, n=1. When n is an integer, the compound is aromatic ( of course it is a planar, no interrupt p orbital... )

(c)

Here nitrogen has an invisible

Anti aromatic