Question

What is an aromatic compound?

Answer 1

An aromatic compound is a COMPOUND that is 1) cyclic, 2) planar, and 3) has a conjugated π system containing `4n+2` π electrons (`n` = whole number).

Explanation:

How to know whether a compound is aromatic or not?

Every π bond is counted as 2 electrons.

Here there is a planar ring with 3 π bonds, and each has two electrons.

So we have `(4n+2)` π electrons (`n = 1`). The compound is aromatic.

A negative charge is counted as 2 electrons.
A positive charge is to be counted as 0 electrons.

The 3-membered cation is aromatic because it has `4n + 2 = 2` π electrons (`n` = 0).

The 5-membered anion is aromatic because it has `4n + 2 = 6` π electrons (`n = 1`).

The 7-membered cation is aromatic because it has `4n + 2 = 6` π electrons (`n = 1`).