I forgot to tell you another workaround, since you are interesting to write chemical formulas: use MathJax plugin.
Just to give you an idea of what you can do:
https://docs.moodle.org/27/en/Chemistry_notation_using_mhchem
I don't know if you already know MathJax, so, to start getting an idea:
https://www.mathjax.org/
If you want to try it, install MathJax from here:
https://www.dokuwiki.org/plugin:mathjax
than, in
Configuration Manager[/m] > [m]MathJax[/m] > [m]config[/m], you have to load the relative module, called [m]"mhchem.js", with:
MathJax.Hub.Config({
tex2jax: {
inlineMath: [ ["$","$"], ["\\(","\\)"] ],
displayMath: [ ["$$","$$"], ["\\[","\\]"] ],
processEscapes: true
},
TeX: {
equationNumbers: {autoNumber: "AMS"},
extensions: ["mhchem.js"]
}
});
Than, in your page, (even in the heading):
$
\ce{your-chemical-formula}
$
Here the MathJax's doc:
http://docs.mathjax.org/en/latest/tex.html#mhchem.