Ok, I finished it at last.
But that level 46 pissed me off big time!
First of all, the name of the element Uranium is Uran
ium, not Uran (and it took me over 100 tries in every other directions until realized that it must be Uranium).
Secondly, what's the logic in listing the next element as an answer? It makes no sense! That's why the "correct" answer was my last try before giving up...
The other levels are ok, there are a few spelling errors here and there, but overall I liked the puzzle very much (
except level 46! ). Oh, and except level 38 which hasn't a correct answer.