# [texhax] units, chemistry and mhchem

Joseph Wright joseph.wright at morningstar2.co.uk
Thu Dec 29 14:32:22 CET 2011

Hello Jon,

> No, mhchem is a good attempt but is flawed.

I think 'flawed' is perhaps a little harsh.

> Chemists use a superscript bullet to denote an unpaired electron or the construct \.{C} or $\dot{C}H_3$
> MHCHEM cannot do this ... the author of the package was reluctant to take my word that that is what we chemists use.
>
> Also we use two superscript dots over the element symbol  to denote a carbene, thus \"{C}

I use mhchem routinely, and have only had one occasion where I've had
the issue with radicals, which I solved using a \raisebox (not ideal, of
course). For carbenes, I'd normally want two dots to the left of the
atom in something like :CH2.

Of course, how important this is depends on the area you work in. I'd
normally have carbenes and radicals in ChemDraw schemes, so don't have
the issue. (I used to work on N-heterocyclic carbenes, so did have a lot
of these to draw.)
--
Joseph Wright