Is this the right place or shall I wait for the chemistry proposal?
I want to ask about Palladium atom. It has 18 electrons in the outer shell. Shouldn't it end with 17,1 instead?
I think that question should be fine.
A rough guideline is that questions about isolated atoms are about physics and are probably okay on this site. Questions about compounds (molecules) or mixtures are likely to be about chemistry and would probably be off-topic here. Of course that's only a rough guideline; the decision has to be made on a case-by-case basis.