# Using chemical formulas

### Using chemical formulas

I've tried using, now be careful: dollar-sign backslash letter "ce" opening-brace chemical-formula closing-brace dollar-sign.

Unlike on Chemistry, it is not working here. Did I make some mistake, is it working differently here or not supported at all?

The $\ce$ command is provided by the mhchem package, which is available in MathJax but currently not loaded by default on Physics or Physics Meta.
A workaround is to use $\require{mhchem}$ somewhere in the question or answer where you need it, e.g.
$$\require{mhchem} \ce{np->d\gamma}$$
Note that, since 2019, statements like \require are local to questions and answers, rather than global to the page, so you’ll have to include this require statement explicitly in each question or answer where you want it.