1. The problem statement, all variables and given/known data Why does the conjugated system (alternance of single and double bonds) of chlorophylles help with photon absorption? 3. The attempt at a solution Since two carbon atoms are equal in electric negativity, no one atom hogs the electrons. In this way, it is easier for photons to excite the electrons. However, I don't understand why single or double bonds would make a difference. Thanks!