A classic formula for pi has been discovered hidden in hydrogen atoms

[jeff47]

23. Some of them do, some of them don't.

You start with the 1S and 2S orbitals. Once those are full, you go through the P orbitals. Once those are full, you go through larger S orbitals. Then you go through larger P orbitals. Then you go through some others....I start losing track at this point.

So, hydrogen has one electron in the 1S orbital. Helium has two electrons, in the 1S and 2S orbitals. And so on.

Chemical bonds are created by atoms sharing these orbitals - the most stable configuration is for each "level" to be full. So hydrogen is desperately trying to react to either fill its 2S orbit or empty its 1S orbit, while helium is stable. Lithium wants to get rid of one electron so it's left with just the 1S and 2S electrons. In Neon, that level of P orbitals is full, so it's stable. And so on through the periodic table.

(This is not 100% precise - the electrons get shared between atoms, but it's a decent enough approximation)