I usually hang out at ChemistrySE, where I use \ce{} to format chemical equations. I once tried to use \ce{} here to write a nuclear reaction, and was perplexed when it didn't work. Someone told me that mhchem isn't enabled here. I ended up having to use \text{} instead.
So, are there any special packages for MathJax here? Or is it just plain old MathJax just like how it's at MathSE?
\require{mhchem}
in order to load mhchem as a one-off for the answer you are writing. E.g.,$\require{mhchem} \ce{H20}$
. You only need to use\require{mhchem}
once on the page." $\endgroup$ – heather Aug 20 '17 at 16:11