The main part of this fic that I really remember is that Loki is trying to describe making elements with magic and he uses "daughters" and "sons" instead of protons and electrons. Before Tony and Bruce figure this out, there is a lost of frustration on Loki's part, since he has no other words to describe the atom. They finally end up showing Loki a diagram to confirm what they believe he is saying.
Anyways, I know it's not a lot but I really appreciate any help with this! I've gone through my bookmarks and everything and still can't find it!