The biggest crown ether experimentally confirmed is 81-crown-27 1 How can this molecule form complexes when the distance between the 27 oxygen atoms which complexes with the cation inside seems extremely large, making coordination seems extremely hard. Moreover, from my understanding of coordinat...

$H^+$ and $He^2$$^+$ both have $0$ electrons. So can we call them isoelectronic or isoelectronic species? If 2 species have difference of protons and neutrons as $0$ , can we call them Isodiaphers? I have to ask the same thing for isotone. I know that only Hydrogen has 0 neutrons. But if there wa...