# [texhax] Units and chemistry

Simmie, John john.simmie at nuigalway.ie
Thu Dec 29 11:00:53 CET 2011

Gord
You might not have problems writing chemistry in math mode
and having chemical formulae in math italic but all
professional chemists would have problems including
the International Union of Pure and Applied Chemists IUPAC
who set the global standards.

So, in math mode you must use \mathrm{CH_3CH_2OH}

Ditto for units these must be in upright/roman and the slash symbol
is deprecated; so velocity in meters per second is written
m s$^{-1}$ and not m/s.  This is because if you are labelling the axis
of a graph with velocity the correct usage is "$v$ / m s$^{-1}$"
the whole thing is properly dimensionless.  Also using the / is
extremely
cumbersome in expressing, for example, the gravitational constant
G whose units are newtons meter squared per kilogram squared
$\mathrm{G} = 6.673 \times 10^{-11}$ N m$^2$ kg$^{-2}$

And yes there must be a space (thinspace, ordinary)
between the number and the unit because they have different properties;
you wouldn't dream of writing 3cats or 16dogs right?

And a happy New Year to you all

John

Emeritus Professor John Simmie::Combustion Chemistry Centre::NUI Galway,
Ireland

> I have no problems with numbers with units being in math italic,
> or even writing chemistry in math mode and having chemical
> formulae in math italic. ?But if one is introducing units, the
> introduction often doesn't have numbers to it (W = J / s), and
> sometimes one forgets to put everything in math mode.
>
> I'm in the habit of \usepackage{isotope} now. ?Is there a similar
> package which allows for nicely typesetting values with units
> (possibly with error estimates)?