Chapter 14, Problem 14.22P

Interpretation Introduction

Interpretation:

The number of $\text{π}$ systems and electrons in $\text{β-carotene}$ are to be given.

Concept introduction:

Electrons can be resonance delocalized over a set of atoms that contribute conjugated p-orbitals to a single $\text{π}$ system of molecular orbitals. For an acyclic conjugated system, the number of $\text{π}$ electrons are the ones that can be shifted via resonance from one end to the other.