Assuming that we get the MathJax support, do we need the mhchem extension? We have this enabled on the Chemistry site, and it's incredibly helpful there in showing anything more complicated than a single molecule. Because the history of chemistry will be on topic here, I expect that it will be helpful here as well.
I don't expect this will be quite as necessary as the broader MathJax support, but I still think it's useful enough and simple enough to add.