Final answer:
Pyrene is aromatic because it contains separate benzenoid rings that follow Hückel's rule, with 6 pi electrons each. The 16 pi electrons in pyrene are not in one loop but are in agreement with the aromatic configuration as they allow for resonance stabilization and confer enhanced stability typical of aromatic compounds.
Step-by-step explanation:
Pyrene is considered aromatic despite having 16 pi electrons because its structure can be thought of as containing benzenoid (benzene-like) rings that follow Hückel's rule. This rule states that a compound can be aromatic if it has 4n+2 pi electrons, where n is any non-negative integer. In the case of pyrene, these 16 pi electrons do not all reside in one continuous loop, but are considered in separate benzenoid rings. These rings have 6 pi electrons each, which is in agreement with Hückel's rule (4n+2, where n=1).
Additionally, pyrene possesses resonance stabilization due to the alternating single and double bonds, causing it to have properties consistent with aromatic compounds, such as increased stability and unique reactivity compared to alkanes. The structure of pyrene allows for a planar geometry and extended conjugation, further contributing to its aromatic character.