Although the phenolate ion has more resonance structures (4) compared to acetate ion (2), acetate is more stable because it has two equivalent resonance structures of same energy. Why does having equivalent resonance structures give more stability? Shouldn't a compound with more resonance struct...

The question What is the name of the molecule that has the greatest number of different atoms? appears to be well-defined as to what kind of answer it expects: a stable and existing molecular compound with the greatest variety in elements. There was a recent similar question that has been deleted...

@jakebeal's excellent answer to Why do animal cells “mistake” rubidium ions for potassium ions? includes the following passage: In the case of potassium versus sodium, which are both very important in biochemistry, a recently discovered mechanism in sodium-potassium pumps uses binding properties...