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+% arara: xelatex
+% !arara: biber
+% !arara: xelatex
+% !arara: xelatex
+\documentclass[DIV11,toc=index,toc=bib]{cnpkgdoc}
+\docsetup{
+ pkg = {[greek=newtx]chemmacros},
+ language = en,
+ title = the \Chemmacros\ bundle,
+ subtitle = {
+ packages \Chemmacros\ (v\csname chemmacros@version\endcsname),
+ \Chemformula\ (v\csname chemformula@version\endcsname),
+ \Ghsystem\ (v\csname ghsystem@version\endcsname) and
+ \Chemgreek\ (v\csname chemgreek@version\endcsname)\\[2ex]
+ {\Large documentation for the \Chemformula\ package}},
+ modules = true,
+ code-box = {skipabove=1ex,skipbelow=1ex},
+ label = {},
+ name = chemformula,
+ url = https://bitbucket.org/cgnieder/chemmacros/
+}
+
+\usepackage{chemfig,booktabs,cancel}
+\usepackage[version=3]{mhchem}
+\usepackage{fontspec}
+\usepackage[oldstyle,proportional]{libertine}
+\usepackage[libertine]{newtxmath}
+\usepackage{libertinehologopatch}
+\setmonofont[Scale=MatchLowercase]{Bitstream Vera Sans Mono}
+
+\cnpkgusecolorscheme{friendly}
+\renewcommand*\othersectionlevelsformat[3]{%
+ \textcolor{main}{#3\autodot}\enskip}
+\renewcommand*\partformat{%
+ \textcolor{main}{\partname~\thepart\autodot}}
+
+\usepackage{fnpct}
+\usepackage[biblatex]{embrac}
+\ChangeEmph{[}[,.02em]{]}[.055em,-.08em]
+\ChangeEmph{(}[-.01em,.04em]{)}[.04em,-.05em]
+
+\pagestyle{headings}
+
+\usepackage[accsupp]{acro}
+\acsetup{
+ long-format=\scshape,
+ short-format=\scshape
+}
+\DeclareAcronym{ghs}{
+ short = ghs ,
+ long = Globally Harmonized System of Classification and Labelling of
+ Chemicals ,
+ pdfstring = GHS ,
+ accsupp = GHS
+}
+\DeclareAcronym{eu}{
+ short = EU ,
+ long = European Union ,
+ pdfstring = EU ,
+ accsupp = EU
+}
+\DeclareAcronym{iupac}{
+ short = iupac ,
+ long = International Union of Pure and Applied Chemistry ,
+ pdfstring = IUPAC ,
+ accsupp = IUPAC
+}
+\DeclareAcronym{UN}{
+ short = un ,
+ long = United Nations ,
+ pdfstring = UN ,
+ accsupp = UN
+}
+\DeclareAcronym{dvi}{
+ short = dvi ,
+ long = device independent file format ,
+ pdfstring = DVI ,
+ accsupp = DVO
+}
+\DeclareAcronym{pdf}{
+ short = pdf ,
+ long = portable document file ,
+ pdfstring = PDF ,
+ accsupp = PDF
+}
+
+\chemsetup{
+ option/synchronize ,
+ chemformula/font-spec={[Numbers=Lining]Linux Libertine O}
+}
+\colorlet{chemformula}{darkgray}
+
+\sisetup{
+ detect-mode=false,
+ mode=text,
+ text-rm=\addfontfeatures{Numbers={Proportional,Lining}}
+}
+
+\usepackage{filecontents}
+
+\begin{filecontents*}{\jobname.ist}
+ preamble "\\begin{theindex}\n Section titles are indicated \\textbf{bold},
+ packages \\textsf{sans serif}, commands \\code{\\textbackslash\\textcolor{code}{brown}},
+ options \\textcolor{key}{\\code{yellow}} and modules (only \\chemmacros)
+ \\textcolor{module}{\\code{blue}}.\\newline\n\n"
+ heading_prefix "{\\bfseries "
+ heading_suffix "\\hfil}\\nopagebreak\n"
+ headings_flag 1
+ delim_0 "\\dotfill\\hyperpage{"
+ delim_1 "\\dotfill\\hyperpage{"
+ delim_2 "\\dotfill\\hyperpage{"
+ delim_r "}\\textendash\\hyperpage{"
+ delim_t "}"
+ suffix_2p "\\nohyperpage{\\,f.}"
+ suffix_3p "\\nohyperpage{\\,ff.}"
+\end{filecontents*}
+
+\usepackage[backend=biber,style=alphabetic,maxbibnames=20]{biblatex}
+\addbibresource{\jobname.bib}
+\begin{filecontents*}{\jobname.bib}
+@book{iupac:greenbook,
+ author = {E. Richard Cohan and Tomislav Cvita\v{s} and Jeremy G. Frey and
+ Bertil Holmström and Kozo Kuchitsu and Roberto Marquardt and Ian Mills and
+ Franco Pavese and Martin Quack and Jürgen Stohner and Herbert L. Strauss and
+ Michio Takami and Anders J Thor},
+ title = {“Quantities, Symbols and Units in Physical Chemistry”, \acs{iupac}
+ Green Book},
+ edition = {3rd Edition. 2nd Printing},
+ year = {2008},
+ publisher = {\acs{iupac} \&\ RSC Publishing, Cambridge}
+}
+@book{iupac:redbook,
+ author = {Neil G. Connelly and Ture Damhus and Richard M. Hartshorn and
+ Alan T. Hutton},
+ title = {“Nomenclature of Inorganic Chemistry”, \acs{iupac} Red Book},
+ year = {2005},
+ publisher = { \acs{iupac} \&\ RSC Publishing, Cambridge},
+ isbn = {0-85404-438-8}
+}
+@misc{eu:ghsystem_regulation,
+ author = {{The European Parliament and The Council of the European Union}},
+ title = {Regulation (EC) No 1272/2008 of the European Parliament and of the Council},
+ subtitle = {on classification, labelling and packaging of substances and mixtures,
+ amending and repealing Directives 67/548/EEC and 1999/45/EC, and amending
+ Regulation (EC) No 1907/2006},
+ journal = {Official Journal of the European Union},
+ date = {2008-12-16}
+}
+@online{unece:ghsystem_implementation,
+ author = {United Nations Economic Commission for Europe},
+ title = {GHS Implementation},
+ url = {http://www.unece.org/trans/danger/publi/ghs/implementation_e.html},
+ urldate = {2012-03-20},
+ date = {2012-03-20}
+}
+\end{filecontents*}
+
+\DeclareInstance{xfrac}{chemformula-text-frac}{text}
+ {
+ scale-factor = 1 ,
+ denominator-bot-sep = -.2ex ,
+ denominator-format = \scriptsize #1 ,
+ numerator-top-sep = -.2ex ,
+ numerator-format = \scriptsize #1 ,
+ slash-right-kern = .05em ,
+ slash-left-kern = .05em
+ }
+
+\usetikzlibrary{calc,positioning,decorations.pathmorphing,patterns}
+
+\pgfdeclaredecoration{penciline}{initial}{
+ \state{initial}[
+ width=+\pgfdecoratedinputsegmentremainingdistance,
+ auto corner on length=1mm
+ ]{
+ \pgfpathcurveto%
+ {% From
+ \pgfqpoint
+ {\pgfdecoratedinputsegmentremainingdistance}
+ {\pgfdecorationsegmentamplitude}
+ }
+ {% Control 1
+ \pgfmathrand
+ \pgfpointadd
+ {\pgfqpoint{\pgfdecoratedinputsegmentremainingdistance}{0pt}}
+ {%
+ \pgfqpoint
+ {-\pgfdecorationsegmentaspect\pgfdecoratedinputsegmentremainingdistance}%
+ {\pgfmathresult\pgfdecorationsegmentamplitude}
+ }
+ }
+ {%TO
+ \pgfpointadd
+ {\pgfpointdecoratedinputsegmentlast}
+ {\pgfpoint{1pt}{1pt}}
+ }
+ }
+ \state{final}{}
+}
+\tikzset{pencil/.style={decorate,decoration=penciline}}
+
+\TitlePicture{%
+ \ch[font-spec={Augie}]{
+ 2 "\OX{o1,\ox{0,Na}}" + "\OX{r1,\ox{0,Cl}}" {}2
+ ->
+ 2 "\OX{o2,\ox{+1,Na}}" {}+ + 2 "\OX{r2,\ox{-1,Cl}}" {}-
+ }
+ \redox(o1,o2)[red,pencil,-cf]{\small\ch[font-spec={[Color=red]Augie},math-space=.3em]{$-$ 2 e-}}
+ \redox(r1,r2)[blue,pencil,-cf][-1]{\small\ch[font-spec={[Color=blue]Augie},math-space=.3em]{$+$ 2 e-}}}
+
+\addcmds{
+ a, abinitio, AddRxnDesc, anti, aq, aqi,
+ b, ba, bond, bottomrule, bridge,
+ cancel, cd, cdot, ce, cee, celsius, centering, chemabove, Chemalpha,
+ Chembeta, Chemgamma, Chemdelta, ChemDelta, chemfig, chemname, Chemomega,
+ chemsetup, cip, cis, ch, clap, cnsetup, CNMR, color, cstack, cstsetup,
+ d, D, data, DeclareChemArrow, DeclareChemBond, DeclareChemBondAlias,
+ DeclareChemIUPAC, DeclareChemLatin, DeclareChemNMR, DeclareChemParticle,
+ DeclareChemPhase, DeclareChemReaction, DeclareChemState, DeclareInstance,
+ DeclareSIUnit, definecolor, delm, delp, Delta, Dfi, draw,
+ E, el, electronvolt, ElPot, endo, Enthalpy, enthalpy, Entropy,
+ footnotesize, fmch, fpch, fscrm, fscrp,
+ g, gas, ghs, ghslistall, ghspic, Gibbs, glqq, gram, grqq,
+ H, hapto, HNMR, Helmholtz, hertz, hspace,
+ includegraphics, insitu, intertext, invacuo, iupac, IUPAC,
+ J, joule,
+ Ka, Kb, kilo, Kw,
+ L, latin, lewis, Lewis, Lfi, listofreactions, lqd, ltn,
+ mch, mega, meta, metre, mhName, midrule, milli, mmHg, mole,
+ N, nano, nicefrac, newman, NMR, Nu, Nuc, num, numrange,
+ O, ominus, orbital, ortho, oplus, ox, OX,
+ p, P, para, pch, per, percent, pgfarrowsdeclarealias, pgfarrowsrenewalias,
+ pH, phase, photon, pKa, pKb, pOH, pos, positron, Pot, prt,
+ R, Rad, redox, RenewChemArrow, RenewChemBond, RenewChemIUPAC,
+ RenewChemLatin, RenewChemNMR, RenewChemParticle, RenewChemPhase,
+ RenewChemState, renewtagform, rightarrow,
+ S, Sf, sample, scriptscriptstyle, scrm, scrp, second, setatomsep,
+ setbondoffset, setchemformula, sfrac, shorthandoff, ShowChemArrow,
+ ShowChemBond, si, SI, sisetup, sld, Sod, square, State, subsection,
+ textcolor, textendash, textsuperscript, tiny, toprule, trans,
+ upbeta, upeta, upgamma,
+ val, volt, vphantom, vspave,
+ w, xspace, Z
+}
+
+\usepackage{imakeidx}
+\indexsetup{othercode=\footnotesize}
+\makeindex[columns=3,intoc,options={-sl \jobname.ist}]
+
+\newcommand*\Chemmacros{%
+ {%
+ \fontspec[Color=main,Scale=1.2]
+ {Linux Biolinum Shadow O}%
+ chemmacros%
+ }%
+}
+\providecommand*\chemmacros{{\scshape\textcolor{main}{chemmacros}}\xspace}
+
+\newcommand*\Chemformula{%
+ {%
+ \fontspec[Color=main,Scale=1.2]
+ {Linux Biolinum Shadow O}%
+ chemformula%
+ }%
+}
+\providecommand*\chemformula{{\scshape\textcolor{main}{chemformula}}\xspace}
+
+\newcommand*\Ghsystem{%
+ {%
+ \fontspec[Color=main,Scale=1.2]
+ {Linux Biolinum Shadow O}%
+ ghsystem%
+ }%
+}
+\providecommand*\ghsystem{{\scshape\textcolor{main}{ghsystem}}\xspace}
+
+\newcommand*\Chemgreek{%
+ {%
+ \fontspec[Color=main,Scale=1.2]
+ {Linux Biolinum Shadow O}%
+ chemgreek%
+ }%
+}
+\providecommand*\chemgreek{{\scshape\textcolor{main}{chemgreek}}\xspace}
+
+\renewcommand*\AmS{\hologo{AmS}}
+
+\newcommand*\Default[1]{%
+ \hfill\llap{%
+ \ifblank{#1}
+ {(initially~empty)}
+ {Default:~\code{#1}}%
+ }\newline
+}
+
+\usepackage{marginnote,ragged2e}
+\makeatletter
+\providecommand*\sinceversion[1]{%
+ \@bsphack
+ \marginnote{%
+ \footnotesize\sffamily\RaggedRight
+ \textcolor{black!75}{Introduced in version~#1}}%
+ \@esphack}
+\providecommand*\changedversion[1]{%
+ \@bsphack
+ \marginnote{%
+ \footnotesize\sffamily\RaggedRight
+ \textcolor{black!75}{Changed in version~#1}}%
+ \@esphack}
+
+\RenewDocumentCommand\CTANurl{O{macros/latex/contrib}m}
+ {%
+ on CTAN: %
+ \hyper@linkurl{#2}{http://mirrors.ctan.org/#1/#2/}%
+ }
+\ExplSyntaxOn
+\RenewDocumentCommand \paket { sO{macros/latex/contrib}m }
+ {
+ \paketfont { #3 }
+ \index { #3 @ \paketfont { #3 } }
+ \prop_if_in:NnF \g_cnpkgdoc_pakete_prop { #3 }
+ {
+ \prop_gput:Nnn \g_cnpkgdoc_pakete_prop { #3 } {}
+ \IfBooleanF { #1 }
+ { \footnote { \CTANurl[]{#3} } }
+ }
+ }
+\ExplSyntaxOff
+\makeatother
+
+\begin{document}
+
+\section{Introduction}
+Probably every chemist using \LaTeXe\ is aware of the great \paket{mhchem}
+package by Martin Hensel. There have always been some difficulties
+intertwining it with \chemmacros, though. Also, some other minor points in
+\paket{mhchem} always bothered me, but they hardly seemed enough for a new
+package. They weren't even enough for a feature request to the \paket{mhchem}
+author. The challenge and the fun of creating a new package and the wish for
+a highly customizable alternative led to \chemformula\ after all.
+
+\chemformula\ works very similar to \paket{mhchem} but is more strict as to how
+compounds, stoichiometric factors and arrows are input. In the same time
+\chemformula\ offers \emph{many} possibilities to customize the output.
+
+\sinceversion{4.0}Since version 4.0, the \chemformula\ package can be used
+independently from \chemmacros. This means that if you say
+\begin{beispiel}[code only]
+ \usepackage{chemformula}
+\end{beispiel}
+then \chemmacros\ will not be loaded. The \chemmacros\ package, however,
+\emph{will} load \chemformula.
+
+\section{Licence and Requirements}
+Permission is granted to copy, distribute and/or modify this software under
+the terms of the \LaTeX\ project public license (lppl) version 1.3 or later
+(\url{http://www.latex-project.org/lppl.txt}). The package has the status
+``maintained.''
+
+The \chemformula\ package needs and thus loads the packages \paket*{expl3}
+(from the \paket*{l3kernel}\footnote{\CTANurl{l3kernel}}), \paket*{xparse},
+\paket*{l3keys2e} and \paket*{xfrac} (from the
+\paket*{l3packages}\footnote{\CTANurl{l3packages}}),
+\paket*{tikz}\footnote{\CTANurl[graphics]{pgf}}, \paket{amsmath},
+\paket*{nicefrac} and \paket*{scrlfile} (from the
+\KOMAScript\footnote{\CTANurl{koma-script}} bundle).
+
+\section{Setup}
+All of \chemformula's options belong to \chemmacros' module
+\textcolor{module}{\code{chemformula}}. This means they can be setup with
+\begin{beispiel}[code only]
+ \chemsetup[chemformula]{<options>} or
+ \chemsetup{chemformula/<option1>,chemformula/<option2>}
+\end{beispiel}
+However, if you're using \chemformula\ as a standalone package the command
+\cmd{chemsetup} is not available. This is why \chemformula\ also has its own
+setup command:
+\begin{beispiel}[code only]
+ \setchemformula{<options>}
+\end{beispiel}
+
+\section{The Basic Principle}
+\chemformula\ offers one main command.
+\begin{beschreibung}
+ \Befehl{ch}[<options>]{<input>}
+\end{beschreibung}
+The usage will seem very familiar to you if you're familiar with \paket{mhchem}:
+\begin{beispiel}
+ \ch{H2O} \\
+ \ch{Sb2O3} \\
+ \ch{H+} \\
+ \ch{CrO4^2-} \\
+ \ch{AgCl2-} \\
+ \ch{[AgCl2]-} \\
+ \ch{Y^{99}+} \\
+ \ch{Y^{99+}} \\
+ \ch{H2_{(aq)}} \\
+ \ch{NO3-} \\
+ \ch{(NH4)2S} \\
+ \ch{^{227}_{90}Th+} \\
+ $V_{\ch{H2O}}$ \\
+ \ch{Ce^{IV}} \\
+ \ch{KCr(SO4)2 * 12 H2O}
+\end{beispiel}
+
+However, there are differences. The most notable one: \chemformula\
+distinguishes between different types of input. These different parts
+\emph{have} to be separated with blanks:
+\begin{beschreibung}
+ \Befehl{ch}{part1 part2 part3 part4}
+\end{beschreibung}
+A blank in the input \emph{never} is a blank in the output. This role of the
+blank strictly holds and disregarding it can have unexpected results and even
+lead to errors.
+
+Another notable difference: \chemformula\ tries to avoid math mode whenever
+possible:
+\begin{beispiel}
+ \ch{A + B ->[a] C} \\
+ \ce{A + B ->[a] C}
+\end{beispiel}
+
+This means that \cmd{ch}{2H2O} is recognized as a \emph{single} part, which in
+this case is recognized as a compound.
+\begin{beispiel}
+ \ch{2H2O} \\
+ \ch{2 H2O}
+\end{beispiel}
+This also means, that a part cannot contain a blank since this will
+automatically divide it into two parts. If you need an extra blank in the
+output you need to use \lstinline+~+. However, since commands in most cases
+gobble a space after them a input like \cmd{ch}{\textbackslash command ABC}
+will be treated as a single part. If you want or need to divide them you need
+to add an empty group: \cmd{ch}{\textbackslash command\{\} ABC}. The
+different input types are described in the following sections.
+
+% TODO: Module überdenken, Beschreibung anpassen
+There are some options to customize the output of the \cmd{ch} command. They
+can either be applied locally using the optional argument or can be set
+globally using the setup command. All options of \chemformula\ belong to the
+module \textcolor{module}{\code{chemformula}} and can be set in different
+ways:
+\begin{beschreibung}
+ \Befehl{chemsetup}[chemformula]{<options>} (when loaded via \chemmacros)
+ \Befehl{chemsetup}{chemformula/<options>} (when loaded via \chemmacros)
+ \Befehl{setchemformula}{<options>} (independent from \chemmacros)
+\end{beschreibung}
+
+\section{Stoichiometric Factors}\secidx{Stoichiometric Factors}
+A stoichiometric factor may only contain of numbers and the signs
+\lstinline+.,_/()+
+\begin{beispiel}
+ \ch{2} \\
+ \ch{12}
+
+ % decimals:
+ \ch{.5} \\
+ \ch{5,75}
+
+ % fractions:
+ \ch{3/2} \\
+ \ch{1_1/2}
+
+ % ``iupac'':
+ \ch{(1/2)}
+\end{beispiel}
+
+As you can see if you input decimal numbers a missing leading zero is added.
+
+You have to be a little bit careful with the right syntax but I believe it is
+rather intuitive.
+\begin{beispiel}[code only]
+ this won't work but will result in an error: \ch{1/1_1}
+\end{beispiel}
+
+If stoichiometric factors are enclosed with parentheses the fractions are not
+recognized and missing leading zeros are not added. What's inside the
+parentheses is typeset as is.
+\begin{beispiel}
+ \ch{(1/2) H2O} \ch{1/2 H2O} \ch{0.5 H2O}
+\end{beispiel}
+You can find many examples like the following for stoichiometric factors in
+parentheses in the \acs{iupac} Green Book~\cite{iupac:greenbook}:
+\begin{reaction*}
+ (1/5) K "\ox*{7,Mn}" O4 + (8/5) HCl == (1/5) "\ox*{2,Mn}" Cl2 + (1/2) Cl2 + (1/5) KCl + (4/5) H2O
+\end{reaction*}
+
+There are a few possibilities to customize the output.
+\begin{beschreibung}
+ \Option{decimal-marker}{<marker>}\Default{.}
+ The symbol to indicate the decimal.
+ \Option{frac-style}{math|xfrac|nicefrac}\Default{math}
+ Determines how fractions are displayed.
+ \Option{stoich-space}{<skip>}\Default{.1667em plus .0333em minus .0117em}
+ The space that is placed after the stoichiometric factor. A rubber
+ length.
+ \Option{stoich-paren-parse}{\default{true}|false}\Default{false}
+ If set to true stoichiometric factors enclosed by parentheses also are
+ parsed.
+\end{beschreibung}
+\begin{beispiel}
+ \ch[decimal-marker={,}]{3.5} \ch[decimal-marker={$\cdot$}]{3,5}
+\end{beispiel}
+
+The option \key{frac-style}{xfrac} uses the \lstinline+\sfrac+ command of the
+\paket{xfrac} package. The output strongly depends on the font you
+use.\secidx[xfrac]{Stoichiometric Factors}
+\begin{beispiel}
+ \ch[frac-style=xfrac]{3/2} \ch[frac-style=xfrac]{1_1/2}
+\end{beispiel}
+\chemformula\ defines the instance \lstinline=formula-text-frac= which you can
+redefine to your needs. See the \paket{xfrac} documentation for further
+information. The default definition is this:
+\begin{beispiel}[code only]
+ \DeclareInstance{xfrac}{chemformula-text-frac}{text}
+ {
+ slash-left-kern = -.15em ,
+ slash-right-kern = -.15em
+ }
+\end{beispiel}
+This document uses the font Linux Libertine~O and the following definition:
+\begin{beispiel}[code only]
+ \DeclareInstance{xfrac}{chemformula-text-frac}{text}
+ {
+ scale-factor = 1 ,
+ denominator-bot-sep = -.2ex ,
+ denominator-format = \scriptsize #1 ,
+ numerator-top-sep = -.2ex ,
+ numerator-format = \scriptsize #1 ,
+ slash-right-kern = .05em ,
+ slash-left-kern = .05em
+ }
+\end{beispiel}
+
+The option \key{frac-style}{nicefrac} uses the \lstinline+\nicefrac+ command
+of the \paket{nicefrac} package.\secidx[nicefrac]{Stoichiometric Factors}
+\begin{beispiel}
+ \ch[frac-style=nicefrac]{3/2} \ch[frac-style=nicefrac]{1_1/2}
+\end{beispiel}
+
+The option \key{stoich-space} allows you to customize the space between
+stoichiometric factor and the group following after
+it.\secidx[space]{Stoichiometric Factors}
+\begin{beispiel}
+ \ch{2 H2O} \\
+ \ch[stoich-space=.3em]{2 H2O}
+\end{beispiel}
+\secidx*{Stoichiometric Factors}
+
+\section{Compounds}\label{ssec:compounds}\secidx{Compounds}
+\chemformula\ determines compounds as the type that ``doesn't fit in anywhere
+else.'' This point will become more clear when you know what the other types
+are.
+\begin{beispiel}
+ \ch{H2SO4} \\
+ \ch{[Cu(NH3)4]^2+}
+\end{beispiel}
+
+\subsection{Adducts}\secidx[adducts]{Compounds}
+\chemformula\ has two identifiers which will create adducts.
+\begin{beschreibung}
+ \Befehl{ch}{A.B}\newline \ch{A.B}
+ \Befehl{ch}{A*B}\newline \ch{A*B}
+\end{beschreibung}
+\begin{beispiel}
+ \ch{CaSO4.H2O} \\
+ \ch{CaSO4*H2O}
+\end{beispiel}
+Since numbers in a compound always are treated as subscripts (see
+section~\ref{ssec:subscripts}) you sometimes need to introduce stoichiometric
+factors for the right output:
+\begin{beispiel}
+ \ch{Na3PO4*12H2O} \\
+ \ch{Na3PO4* 12 H2O} \\
+ \ch{Na3PO4 * 12 H2O}
+\end{beispiel}
+
+\subsection{Subscripts}\label{ssec:subscripts}\secidx[subscripts]{Compounds}
+\emph{All} numbers in a compound are treated as subscripts.
+\begin{beispiel}
+ \ch{H2SO4}
+\end{beispiel}
+If you want a letter to be a subscript you can use the math syntax:
+\begin{beispiel}
+ \ch{A_nB_m}
+\end{beispiel}
+The subscript recognizes groups. You can also use math inside it.
+\begin{beispiel}
+ \ch{A_{$n$}B_{$m$}} \\
+ \ch{NaCl_{(aq)}}
+\end{beispiel}
+
+\subsection{Commands}\secidx[commands]{Compounds}
+Commands are allowed in a compound:
+\begin{beispiel}
+ \ch{\textbf{A2}B3} \ch{A2\color{red}B3}
+\end{beispiel}
+
+However, if the commands demand numbers as argument, \eg, space commands or
+\chemmacros' \lstinline+\ox+ command the direct use will fail. This is
+because the numbers are treated as subscripts \emph{before} the command
+expands.
+\begin{beispiel}[code only]
+ \ch{A\hspace{2mm}B} will raise an error because \hspace sees something like
+ this: \hspace{$_2$mm}. Actually not at all like it but equally bad\ldots
+\end{beispiel}
+See section~\ref{ssec:text} for a way around this.
+
+\subsection{Charges and Other Superscripts}\secidx[charges]{Compounds}\secidx[superscripts]{Compounds}
+\paragraph{Basics}
+If a compound \emph{ends} with a plus or minus sign it will be treated as
+charge sign and typeset as superscript. In other places a plus is treated as
+a triple bond and a dash will be used as a single bond, see
+section~\ref{ssec:bonds}.
+\begin{beispiel}
+ \ch{A+B} \ch{AB+} \\
+ \ch{A-B} \ch{AB-}
+\end{beispiel}
+
+For longer charge groups or other superscripts you can use the math syntax.
+It recognizes groups and you can use math inside them. Inside these groups
+neither \code{+} nor \code{-} are treated as bonds. If a dot \code{.} is
+inside a superscript it is treated as indicator for a radical. A \code{*}
+gives the excited state.
+\begin{beispiel}
+ \ch{A^{x-}} \\
+ \ch{A^x-} \\
+ \ch{A^{x}-} \\
+ \ch{A^{$x-$}} \\
+ \ch{RNO2^{-.}} \\
+ \ch{^31H} \\
+ \ch{^{14}6C} \\
+ \ch{^{58}_{26}Fe} \\
+ \ch{NO^*}
+\end{beispiel}
+
+Ions and ion composites with more than one charge can be typeset quite as
+easy:
+\begin{beispiel}
+ \ch{SO4^2-} \ch{Ca^2+ SO4^2-}
+\end{beispiel}
+
+\paragraph{Charge Commands}\secidx[superscripts!charge commands]{Compounds}
+You don't need to use \cmd{mch} and related commands inside \cmd{ch}. Indeed,
+you \emph{shouldn't} use them as they might mess with the subscript and
+superscript alignment. The \chemmacros\ option \code{circled} is obeyed by
+\cmd{ch}.
+\begin{beispiel}
+ \chemsetup[option]{circled=all}
+ \ch{H+ + OH- <=> H2O}
+\end{beispiel}
+
+\paragraph{Behaviour}\secidx[superscripts!behaviour]{Compounds}
+The supercripts behave differently depending on their position in a compound,
+if there are super- and subscripts following each other directly.
+\begin{beispiel}
+ \ch{^33B} \ch{{}^33B} \ch{3^3B} \ch{B^3} \ch{B3^3} \\
+ \ch{^{23}_{123}B} \ch{{}^{23}_{123}B} \ch{_{123}^{23}B} \ch{B^{23}} \ch{B_{123}^{23}} \\
+ \ch{^{123}_{23}B} \ch{{}^{123}_{23}B} \ch{_{23}^{123}B} \ch{B^{123}} \ch{B23^{123}}
+\end{beispiel}
+\begin{itemize}
+\item If a compound \emph{starts} with a sub- or superscript both sub- and
+ superscript are aligned to the \emph{right} else to the \emph{left}.
+\item If a compound \emph{does not start} with a sub- or superscript and there
+ is both a sub- and a superscript, the superscript is shifted additionally by
+ a length determined from the option \key{charge-hshift}{<dim>}, also see
+ page~\pageref{desc:charge-hshift}f.
+\end{itemize}
+The second point follows \ac{iupac}'s recommendations:
+\begin{zitat}[{\acs{iupac} Green Book {\cite[][p.\,51]{iupac:greenbook}}}]
+ In writing the formula for a complex ion, spacing for charge number can be
+ added (staggered arrangement), as well as parentheses:
+ \ch[charge-hshift=full]{SO4^2-}, \ch{(SO4)^2-} The staggered arrangement is
+ now recommended.
+\end{zitat}
+
+\subsection{Bonds}\label{ssec:bonds}\secidx[bonds]{Compounds}
+\subsubsection{Native Bonds}
+There are three kinds of what I will call ``native bonds'':
+\begin{beispiel}
+ single: \ch{CH3-CH3} \\
+ double: \ch{CH2=CH2} \\
+ triple: \ch{CH+CH}
+\end{beispiel}
+
+\subsubsection{Flexible Bonds}
+\paragraph{Predefined Bonds}
+In addition to the three native bonds there are a few more which can be called
+by
+\begin{beschreibung}
+ \Befehl{bond}{<bond name>}
+\end{beschreibung}
+The predefined bond types are shown in table~\ref{tab:bond_types}.
+
+\begin{table}
+ \centering
+ \caption{Bonds available with \protect\cmd{bond}.}
+ \label{tab:bond_types}
+ \begin{tabular}{lcl}
+ \toprule
+ \bfseries name & \bfseries appearance & \bfseries aliases \\
+ \midrule
+ \code{single} & \bond{single} & \code{normal}, \code{sb} \\
+ \code{double} & \bond{double} & \code{db} \\
+ \code{triple} & \bond{triple} & \code{tp} \\
+ \code{dotted} & \bond{dotted} & \code{semisingle} \\
+ \code{deloc} & \bond{deloc} & \code{semidouble} \\
+ \code{tdeloc} & \bond{tdeloc} & \code{semitriple} \\
+ \code{co>} & \bond{co>} & \code{coordright} \\
+ \code{<co} & \bond{<co} & \code{coordleft} \\
+ \bottomrule
+ \end{tabular}
+\end{table}
+
+\begin{beispiel}
+ \ch{C\bond{sb}C\bond{db}C\bond{tp}C\bond{deloc}C\bond{tdeloc}C\bond{co>}C\bond{<co}C}
+\end{beispiel}
+
+\paragraph{Own Bonds}
+\chemformula\ offers commands to define own bond types:
+\begin{beschreibung}
+ \Befehl{DeclareChemBond}{<name>}\ma{<code>}
+ \Befehl{RenewChemBond}{<name>}\ma{<code>}
+ \Befehl{DeclareChemBondAlias}{<new name>}\ma{<old name>}
+ \Befehl{ShowChemBond}{<name>}
+\end{beschreibung}
+The usage is best described with an example. So let's see how the
+\code{single} bond and the \code{co>} bond are defined:
+\begin{beispiel}[code only]
+ \DeclareChemBond{single}
+ { \draw[chembond] (chemformula-bond-start) -- (chemformula-bond-end) ; }
+ \DeclareChemBond{coordright}
+ { \draw[chembond,butt cap->] (chemformula-bond-start) -- (chemformula-bond-end) ; }
+ \DeclareChemBondAlias{co>}{coordright}
+\end{beispiel}
+Two points are important: the names of the starting and the ending
+coordinates, \code{chemformula-bond-start} and \code{chemformula-bond-end},
+and the \TikZ style of the bonds \code{chembond}.
+
+So, let's say you want to define a special kind of dashed bond. You could do
+this:
+\begin{beispiel}
+ \usetikzlibrary{decorations.pathreplacing}
+ \makeatletter
+ \DeclareChemBond{dashed}
+ {
+ \draw[
+ chembond,
+ decorate,
+ decoration={ticks,segment length=\chemformula@bondlength/10,amplitude=1.5pt}]
+ (chemformula-bond-start) -- (chemformula-bond-end) ;
+ }
+ \makeatother
+ \chemsetup[chemformula]{bond-length=2ex}
+ \ch{C\bond{dashed}C}
+\end{beispiel}
+
+The last example showed you another macro:
+\makeatletter\cmd{chemformula@bondlength}\makeatother. It only exists so you
+can use it to access the bond length as set with \key{bond-length}
+directly.
+
+\subsection{Customization}\secidx[customization]{Compounds}\label{ssec:compounds:customization}
+These options allow you to customize the ouptut of the compounds:
+\begin{beschreibung}
+ \Option{subscript-vshift}{<dim>}\Default{0pt}
+ Extra vertical shift of the subscripts.
+ \Option{subscript-style}{text|math}\Default{text}
+ Style that is used to typeset the subscripts.
+ \Option{charge-hshift}{<dim>}\Default{.25em}
+ Shift of superscripts when following a subscript.\label{desc:charge-hshift}
+ \Option{charge-vshift}{<dim>}\Default{0pt}
+ Extra vertical shift of the superscripts.
+ \Option{charge-style}{text|math}\Default{text}
+ Style that is used to typeset the superscripts.
+ \Option{adduct-space}{<dim>}\Default{.1333em}
+ Space to the left and the right of the adduct point.
+ \Option{bond-length}{<dim>}\Default{.5833em}
+ The length of the bonds.
+ \Option{bond-offset}{<dim>}\Default{.07em}
+ Space between bond and atoms.
+ \Option{bond-style}{<tikz>}\Default{}
+ \TikZ\ options for the bonds.
+ \Option{radical-style}{<tikz>}\Default{}
+ \TikZ\ options for the radical point.
+ \Option{radical-radius}{<dim>}\Default{.2ex}
+ The radius of the radical point.
+ \Option{radical-hshift}{<dim>}\Default{.15em}
+ Horizontal shift before the radical point is drawn.
+ \Option{radical-vshift}{<dim>}\Default{.5ex}
+ Vertical shift relative to the current baseline.
+ \Option{radical-space}{<dim>}\Default{.15em}
+ Horizontal shift after the radical point is drawn.
+\end{beschreibung}
+
+Maybe you have noticed that charges of certain ions are shifted to the
+right.\secidx[charges!shift]{Compounds}
+\begin{beispiel}
+ \ch{SO4^2-} \ch{NH4+} \ch{Na+}
+\end{beispiel}
+They are shifted if they \emph{follow} a subscript which follows \ac{iupac}
+recommendations~\cite[][p.\,51]{iupac:greenbook}. The amount of the shift can
+be set with the option \key{charge-hshift}.
+\begin{beispiel}
+ \ch{SO4^2-} \ch{NH4+} \ch{Na+} \\
+ \chemsetup[chemformula]{charge-hshift=.5ex}
+ \ch{SO4^2-} \ch{NH4+} \ch{Na+} \\
+ \chemsetup[chemformula]{charge-hshift=.5pt}
+ \ch{SO4^2-} \ch{NH4+} \ch{Na+}
+\end{beispiel}
+
+Despite \ac{iupac}'s recommendation \chemformula\ does not make fully staggered
+arrangements in the default setting as I find it hard to read in some cases
+and ugly in others. Since this is a subjective decision \chemformula\ not only
+let's you define the absolute amount of the shift but also provides a
+possibility for full staggered arrangements. For this you have to use
+\key{charge-hshift}{full}.
+\begin{beispiel}
+ \ch[charge-hshift=0pt]{C5H11+} \ch[charge-hshift=0pt]{SO4^2-} \\
+ \ch{C5H11+} \ch{SO4^2-} \\
+ \ch[charge-hshift=1ex]{C5H11+} \ch[charge-hshift=1ex]{SO4^2-} \\
+ \ch[charge-hshift=full]{C5H11+} \ch[charge-hshift=full]{SO4^2-}
+\end{beispiel}
+
+If you don't want the charges to be typeset in text mode you can switch to
+math mode:
+\begin{beispiel}
+ \ch{M^x+} \ch{SO4^2-} \\
+ \chemsetup[chemformula]{charge-style = math}
+ \ch{M^x+} \ch{SO4^2-}
+\end{beispiel}
+
+The option \key{subscript-vshift} can be used to adjust the vertical shift of
+the subscripts:\secidx[subscripts!shift]{Compounds}
+\begin{beispiel}
+ \ch{H2SO4} \ch{Na3PO4} \\
+ \chemsetup[chemformula]{subscript-vshift=.5ex}
+ \ch{H2SO4} \ch{Na3PO4} \\
+ \chemsetup[chemformula]{subscript-vshift=-.2ex}
+ \ch{H2SO4} \ch{Na3PO4}
+\end{beispiel}
+
+You can choose the mode subscripts are typeset in the same way as it is
+possible for the charges:
+\begin{beispiel}
+ \ch{A_nB_m} \ch{H2SO4} \\
+ \chemsetup[chemformula]{subscript-style = math}
+ \ch{A_nB_m} \ch{H2SO4}
+\end{beispiel}
+
+The option \key{adduct-space} sets the space left and right to the adduct
+symbol $\cdot$.
+\begin{beispiel}
+ \ch{Na3PO3*H2O} \\
+ \chemsetup[chemformula]{adduct-space=.2em}
+ \ch{Na3PO3*H2O}
+\end{beispiel}
+
+Changing the length of the bonds:\secidx[bonds!length]{Compounds}
+\begin{beispiel}
+ \chemsetup[chemformula]{bond-length=4mm}%
+ single: \ch{CH3-CH3} \\
+ double: \ch{CH2=CH2} \\
+ triple: \ch{CH+CH}
+\end{beispiel}
+
+You can change the distance between bond and atom, too:
+\begin{beispiel}
+ \ch{H-H + N+N + O=O} \\
+ \ch[bond-offset=1pt]{H-H + N+N + O=O}
+\end{beispiel}
+
+\subsection{Standalone Formulae}\secidx[standalone]{Compounds}
+\noindent\sinceversion{4.0}\chemformula\ offers a command that \emph{only
+ accepts} the \enquote{compound} input type:
+\begin{beschreibung}
+ \Befehl{chcpd}[<options>]{<compound>}
+\end{beschreibung}
+\secidx*{Compounds}
+
+\section{Special Input Types}\secidx{Special Types}
+There are some \enquote{special type} input groups.
+
+\subsection{Single Token Groups}\secidx[single token groups]{Special Types}
+The first kind are groups which consist of only one token, namely of the
+following ones:
+\begin{beschreibung}
+ \Befehl{ch}{ + } \ch{ + }\newline
+ Creates the plus sign between compounds with space around it:\\
+ \cmd{ch}{2 Na + Cl2} \ch{2 Na + Cl2}
+ \Befehl{ch}{ v } \ch{ v }\newline
+ Sign for precipitate: \cmd{ch}{BaSO4 v} \ch{BaSO4 v}
+ \Befehl{ch}{ \lstinline+^+ } \ch{ ^ }\newline
+ Sign for escaping gas\footnotemark: \cmd{ch}{\lstinline=H2 ^=}
+ \ch{H2 ^}
+\end{beschreibung}
+\footnotetext{Is this the correct English term? Please correct me if it isn't.}
+
+The space left and right of the plus sign can be set with this option:
+\begin{beschreibung}
+ \Option{plus-space}{<skip>}\Default{.3em plus .1em minus .1em}
+ A rubber length.
+\end{beschreibung}
+\begin{beispiel}
+ \ch{A + B}\\
+ \ch[plus-space=4pt]{A + B}
+\end{beispiel}
+
+\subsection{Option Input}\secidx[option input]{Special Types}
+Sometimes you might want to apply an option only to a part of a, say,
+reaction. Of course you have the possibility to use \cmd{ch} several times.
+\begin{beispiel}
+ \ch{H2O +}\textcolor{red}{\ch{H2SO4}}\ch{-> H3O+ + HSO4-} \\
+ \ch{H2O +}\ch[subscript-vshift=2pt]{H2SO4}\ch{-> H3O+ + HSO4-}
+\end{beispiel}
+This, however, interrupts the input in your source and \emph{may} mess with
+the spacing. That's why there is an alternative:
+\begin{beschreibung}\makeatletter
+ \Befehl{ch}{ @\{<options>\} }\newline
+ The options specified this way will be valid \emph{only} until the next
+ compound is set.
+\end{beschreibung}
+\begin{beispiel}
+ \ch{H2O +}\textcolor{red}{\ch{H2SO4}}\ch{-> H3O+ + HSO4-} \\
+ \ch{H2O + @{format=\color{red}} H2SO4 -> H3O+ + HSO4-} \\
+ or of course:\\
+ \ch{H2O + \textcolor{red}{H2SO4} -> H3O+ + HSO4-}\\[1em]
+ \ch{H2O +}\ch[subscript-vshift=2pt]{H2SO4}\ch{-> H3O+ + HSO4-} \\
+ \ch{H2O + @{subscript-vshift=2pt} H2SO4 -> H3O+ + HSO4-}
+\end{beispiel}
+\secidx*{Special Types}
+
+\section{Escaped Input}\secidx{Escaped Input}
+In some cases it may be desirable to prevent \chemformula\ from parsing the
+input. This can be done in two ways.
+
+\subsection{Text}\label{ssec:text}\secidx[text]{Escaped Input}
+If you put something between \lstinline+" "+ or \lstinline+' '+ then the input
+will be treated as normal text, except that spaces are not allowed and have to
+be input with \lstinline+~+.
+\begin{beschreibung}
+ \Befehl{ch}{ "<escaped text>" }
+ \Befehl{ch}{ '<escaped text>' }
+\end{beschreibung}
+\begin{beispiel}
+ \ch{"\ox{2,Ca}" O} \\
+ \ch{"\ldots\," Na + "\ldots\," Cl2 -> "\ldots\," NaCl} \\
+ \ch{'A~->~B'}
+\end{beispiel}
+In many cases you won't need to escape the input. But when you get into
+trouble when using a command inside \cmd{ch} try hiding it.
+
+\subsection{Math}\secidx[math]{Escaped Input}
+If you especially want to input math you just enclose it with \lstinline+$ $+.
+This output is different from the escaped text as it is followed by a space.
+The reasoning behind this is that I assume math will mostly be used to replace
+stoichiometric factors.
+\begin{beschreibung}
+ \Befehl{ch}{ \string$<escaped math>\string$ }
+ \Befehl{ch}{ \string\(<escaped math>\string\) }
+\end{beschreibung}
+\begin{beispiel}
+ escaped text: \ch{"$x$" H2O} \\
+ escaped math: \ch{$x$ H2O} \\
+ also escaped math: \ch{\(x\) H2O} \\
+ \ch{$2n$ Na + $n$ Cl2 -> $2n$ NaCl}
+\end{beispiel}
+
+The space that is inserted after a math group can be edited:
+\begin{beschreibung}
+ \Option{math-space}{<skip>}\Default{.1667em plus .0333em minus .0117em}
+ A rubber length.
+\end{beschreibung}
+\begin{beispiel}
+ \ch{$2n$ Na + $n$ Cl2 -> $2n$ NaCl} \\
+ \chemsetup[chemformula]{math-space=.25em}
+ \ch{$2n$ Na + $n$ Cl2 -> $2n$ NaCl} \\
+ \ch{$A->B$}
+\end{beispiel}
+\secidx*{Escaped Input}
+
+\section{Arrows}\label{sec:arrows}\secidx{Arrows}
+\subsection{Arrow types}\secidx[types]{Arrows}
+Arrows are input in the same intuitive way they are with \paket{mhchem}.
+There are various different types:
+\begin{beschreibung}
+ \Befehl{ch}{ -> } \ch{->}\newline
+ standard right arrow
+ \Befehl{ch}{ <- } \ch{<-}\newline
+ standard left arrow
+ \Befehl{ch}{ -/> } \ch{-/>}\newline
+ does not react (right)
+ \Befehl{ch}{ </- } \ch{}</-\newline
+ does not react (left)
+ \Befehl{ch}{ <-> } \ch{<->}\newline
+ resonance arrow
+ \Befehl{ch}{ <> } \ch{<>}\newline
+ reaction in both directions
+ \Befehl{ch}{ == } \ch{==}\newline
+ stoichiometric equation
+ \Befehl{ch}{ <=> } \ch{<=>}\newline
+ equilibrium arrow
+ \Befehl{ch}{ \lstinline+<=>>+ } \ch{<=>>}\newline
+ unbalanced equilibrium arrow to the right
+ \Befehl{ch}{ \lstinline+<<=>+ } \ch{<<=>}\newline
+ unbalanced equilibrium arrow to the left
+ \Befehl{ch}{ <o> } \ch{<o>}\newline
+ isolobal arrow
+\end{beschreibung}
+All these arrows are drawn with \TikZ.
+\begin{beispiel}
+ \ch{H2 + Cl2 -> 2 HCl} \\
+ \ch{H2O + CO3^2- <=> OH- + HCO3-} \\
+ \ch{A <- B} \\
+ \ch{\{[CH2=CH-CH2]- <-> [CH2-CH=CH2]- \}} \\
+ \ch{A <> B} \\
+ \ch{H+ + OH- <=>> H2O} \\
+ \ch{2 NO2 <<=> N2O4}
+\end{beispiel}
+
+% TODO: add description for \charrow
+
+\subsection{Labels}\secidx[labels]{Arrows}
+The arrows take two optional arguments to label them.
+\begin{beschreibung}
+ \Befehl{ch}{ ->[<above>][<below>] }
+\end{beschreibung}
+\begin{beispiel}
+ \ch{A ->[a] B} \\
+ \ch{A ->[a][b] B} \\
+ \ch{A ->[\SI{100}{\celsius}] B}
+\end{beispiel}
+The label text can be parsed seperately from the arrow. The recipe is easy:
+leave blanks.
+\begin{beispiel}
+ \ch{A ->[H2O] B} \\
+ \ch{A ->[ H2O ] B} \\
+ \ch{A ->[ "\ox{2,Ca}" F2 ] B} \\
+ \ch{A ->[$\Delta$,~ \[H+ \]] B}
+\end{beispiel}
+% TODO: correct info about []
+
+If you leave the blanks \chemformula\ treats the groups inside the square
+brackets as seperated input types. The arrow reads its arguments
+\emph{afterwards}. As you can see the arrows \enquote{grow} with the length
+of the labels. What stays constant is the part that protrudes the labels. As
+you also can see in the last example square brackets inside the arrow
+arguments should be produced using \cmd{[} and \cmd{]}. They keep their usual
+meaning outside \cmd{ch}. These commands are necessary since the usual
+grouping (\ie hiding the brackets inside curly brackets) doesn't work due to
+the way \cmd{ch} reads its argument.
+\begin{beispiel}
+ \ch{A ->[a] B} \\
+ \ch{A ->[ab] B} \\
+ \ch{A ->[abc] B} \\
+ \ch{A ->[abc~abc] B} \\
+ % needs the `chemfig' package:
+ \setatomsep{15pt}
+ \ch{A ->[ "\chemfig{-[:30]-[:-30]OH}" ] B} \\
+ \ch{A ->[[]] B} vs. \ch{A ->[\[\]] B}
+\end{beispiel}
+
+\subsection{Customization}\secidx[customization]{Arrows}
+These are the options which enable you to customize the arrows:
+\begin{beschreibung}
+ \Option{arrow-offset}{<dim>}\Default{.75em}
+ This is the length that an arrow protrudes a label on both sides. This
+ means an empty arrow's length is two times \code{arrow-offset}.
+ \Option{arrow-min-length}{<dim>}\Default{0pt}
+ The minimal length an error must have unless two times \key{arrow-offset}
+ plus the width of the label is larger.
+ \Option{arrow-yshift}{<dim>}\Default{0pt}
+ Shifts an arrow up (positive value) or down (negative value).
+ \Option{arrow-ratio}{<factor>}\Default{.6}
+ The ratio of the arrow lengths of the unbalanced equilibrium. \code{.4}
+ would mean that the length of the shorter arrow is $0.4\times$ the length
+ of the longer arrow.
+ \Option{compound-sep}{<dim>}\Default{.5em}
+ The space between compounds and the arrows.
+ \Option{label-offset}{<dim>}\Default{2pt}
+ The space between the labels and the arrows.
+ \Option{label-style}{<font command>}\Default{\cmd*{footnotesize}}
+ The relative font size of the labels.
+\end{beschreibung}
+
+The following code shows the effect of the different options on the \lstinline+<=>>+
+arrow:
+\begin{beispiel}
+ standard: \ch{A <=>>[x][y] B} \\
+ longer: \ch[arrow-offset=12pt]{A <=>>[x][y] B} \\
+ higher: \ch[arrow-yshift=2pt]{A <=>>[x][y] B} \\
+ more balanced: \ch[arrow-ratio=.8]{A <=>>[x][y] B} \\
+ labels further away: \ch[label-offset=4pt]{A <=>>[x][y] B} \\
+ larger distance to compounds: \ch[compound-sep=2ex]{A <=>>[x][y] B} \\
+ smaller labels: \ch[label-style=\tiny]{A <=>[x][y] B}
+\end{beispiel}
+
+\subsection{Modify Arrow Types}\label{sec:arrows_modify}\secidx[types!modify]{Arrows}
+The arrows are defined with the command
+\begin{beschreibung}
+ \Befehl{DeclareChemArrow}{<tokens>}\ma{<tikz>}
+\end{beschreibung}
+\ma{<tokens>} is the sequence of tokens that is replaced with the actual arrow
+code. For example the basic arrow is defined via
+\begin{beispiel}[code only]
+ \DeclareChemArrow{->}{\draw[-cf] (cf_arrow_start) -- (cf_arrow_end) ;}
+\end{beispiel}
+In order to define arrows yourself you need to know the basics of
+\TikZ\footnote{Please see the \textsf{pgfmanual} for details.}. There are
+some predefined coordinates you can and should use:
+\begin{description}
+ \item[\code{(cf\_arrow\_start)}] The beginning of the arrow.
+ \item[\code{(cf\_arrow\_end)}] The end of the arrow.
+ \item[\code{(cf\_arrow\_mid)}] The mid of the arrow.
+ \item[\code{(cf\_arrow\_mid\_start)}] The beginning of the shorter arrow in
+ types like \lstinline+<=>>+.
+ \item[\code{(cf\_arrow\_mid\_end)}] The end of the shorter arrow in types like
+ \lstinline+<=>>+.
+ \item[\code{cf}, \code{left cf}, \code{right cf}] \chemformula's own arrow
+ heads.
+\end{description}
+\begin{beispiel}
+ \DeclareChemArrow{.>}{\draw[-cf,dotted,red] (cf_arrow_start) -- (cf_arrow_end);}
+ \DeclareChemArrow{n>}{\draw[-cf] (cf_arrow_start) .. controls ([yshift=3ex]cf_arrow_mid) .. (cf_arrow_end);}
+ \ch{A .> B} \ch{A .>[a][b] B} \ch{A n> B}
+\end{beispiel}
+If you want to redefine an existing arrow there are two commands you can use:
+\begin{beschreibung}
+ \Befehl{RenewChemArrow}{<tokens>}\ma{<tikz>}
+ \Befehl{ShowChemArrow}{<tokens>}
+\end{beschreibung}
+The second one gives the current definition, the first one redefines an existing
+arrow.
+\begin{beispiel}
+ \texttt{\ShowChemArrow{->}} \\
+ \RenewChemArrow{->}{\draw[->,red] (cf_arrow_start) -- (cf_arrow_end) ;}
+ \texttt{\ShowChemArrow{->}} \\
+ \ch{A -> B}
+\end{beispiel}
+
+\subsection{Standalone Arrows}\secidx[standalone]{Arrows}
+\noindent\sinceversion{4.0}\chemformula\ offers a command that \emph{only
+ accepts} the \enquote{arrow} input type:
+\begin{beschreibung}
+ \Befehl{charrow}{<arrow>}\oa{<above>}\oa{<below>}
+\end{beschreibung}
+\secidx*{Arrows}
+
+\section{Names}\secidx{Names}
+\subsection{Syntax}\secidx[syntax]{Names}
+\chemformula\ has a built-in syntax to write text under a compound. In a way
+it works very similar to the arrows.
+\begin{beschreibung}
+ \Befehl{ch}{ !(<name>)( <formula> ) }
+\end{beschreibung}
+If an exclamation mark is followed by a pair of parentheses \chemformula\ will
+parse it this way:
+\begin{beispiel}
+ \ch{!(ethanol)( CH2CH2OH )}
+\end{beispiel}
+The same what's true for the arrows arguments holds for these arguments: if
+you leave blanks the different parts will be treated according to their input
+type before the text is set below the formula.
+\begin{beispiel}
+ \ch{!(water)(H2O)} \quad
+ \ch{!( "\textcolor{blue}{water}" )( H2O )} \quad
+ \ch{!( $2n-1$ )( H2O )} \quad
+ \ch{!( H2O )( H2O )} \quad
+ \ch{!(oxonium)( H3O+ )}
+\end{beispiel}
+If for some reason you want to insert an exclamation mark \emph{without} it
+creating a name you only have to make sure it isn't followed by parentheses.
+\begin{beispiel}
+ \ch{H2O~(!)} \\
+ \ch{A!{}()}
+\end{beispiel}
+
+% TODO add description of \chname command
+
+\subsection{Customization}\secidx[customization]{Names}
+\chemformula\ provides two options to customize the output of the names:
+\begin{beschreibung}
+ \Option{name-format}{<commands>}\Default{\cmd*{scriptsize}\cmd*{centering}}
+ The format of the name. This can be arbitrary input.
+ \Option{name-width}{<dim>|auto}\Default{auto}
+ The width of the box where the label is put into. \code{auto} will detect
+ the width of the name and set the box to this width.
+\end{beschreibung}
+\begin{beispiel}
+ \ch{!(acid)( H2SO4 ) -> B} \\
+ \ch[name-format=\sffamily\small]{!(acid)( H2SO4 ) -> B} \\
+ \ch[name-format=\scriptsize N:~]{!(acid)( H2SO4 ) -> B} \\
+ \ch[name-width=3em,name-format=\scriptsize\raggedright]{!(acid)( H2SO4 ) -> B}
+\end{beispiel}
+
+\subsection{Standalone Names}\secidx[standalone]{Names}
+\noindent\sinceversion{4.0}\chemformula\ offers a command that allows the
+usage of the \enquote{name} syntax in normal text. This is the command that
+a bang is replaced with in \chemformula's formulas, actually. Both arguments
+are mandatory.
+\begin{beschreibung}
+ \Befehl{chname}\da{<under>}\da{<text>}
+\end{beschreibung}
+\secidx*{Names}
+
+\section{Format and Font}\secidx{Format and Font}\label{sec:format}
+In the standard setting \chemformula\ doesn't make any default changes to the
+font of the formula output. Let's take a look at a nonsense input which shows
+all features:
+\begin{beispiel}
+ \newcommand*\sample{%
+ \ch{H2C-C+C-CH=CH+ + CrO4^2-
+ <=>[x][y]
+ 2.5 Cl^{-.} + 3_1/2 Na*OH_{(aq)} + !(name)( A^n ) "\LaTeXe"}
+ }
+ \sample
+\end{beispiel}
+\newcommand*\sample{%
+ \ch{H2C-C+C-CH=CH+ + CrO4^2-
+ <=>[x][y]
+ 2.5 Cl^{-.} + 3_1/2 Na*OH_{(aq)} + !(name)( A^n ) "\LaTeXe"}
+}
+
+Now we're going to change different aspects of the font a look what happens:
+\begin{beispiel}[below]
+ \sffamily Hallo \sample \\
+ \ttfamily Hallo \sample \normalfont \\
+ \bfseries Hallo \sample \normalfont \\
+ \itshape Hallo \sample
+\end{beispiel}
+As you can see most features adapt to the surrounding font.
+
+If you want to change the default format you need to use this option:
+\begin{beschreibung}
+ \Option{format}{<anything>}\Default{}
+ Adds arbitrary code before the output of \cmd{ch}.
+\end{beschreibung}
+\begin{beispiel}
+ \definecolor{newblue}{rgb}{.1,.1,.5}
+ \chemsetup[chemformula]{format=\color{newblue}\sffamily}
+ \sffamily Hallo \sample \\
+ \ttfamily Hallo \sample \normalfont \\
+ \bfseries Hallo \sample \normalfont \\
+ \itshape Hallo \sample
+\end{beispiel}
+
+You can also specifically change the fontfamily, fontseries and fontshape of
+the output.
+\begin{beschreibung}
+ \Option{font-family}{<family>}\Default{}
+ Changes the fontfamily of the output with
+ \lstinline+\fontfamily{<family>}\selectfont+.
+ \Option{font-series}{<series>}\Default{}
+ Changes the fontseries of the output with
+ \lstinline+\fontseries{<series>}\selectfont+.
+ \Option{font-shape}{<shape>}\Default{}
+ Changes the fontshape of the output with
+ \lstinline+\fontshape{<shape>}\selectfont+.
+\end{beschreibung}
+\begin{beispiel}
+ \chemsetup[chemformula]{font-series=bx}
+ Hallo \sample \\
+ \sffamily Hallo \sample \normalfont \\
+ \chemsetup[chemformula]{font-family=lmr,font-series=m} Hallo \sample \normalfont \\
+ \itshape Hallo \sample
+\end{beispiel}
+
+If you're using \XeLaTeX\ or \LuaLaTeX\ and have loaded \paket{fontspec} you
+have the possibilty to set the font with it:
+\begin{beschreibung}
+ \Option{font-spec}{\{<font>\}}\Default{}
+ or with options
+ \Option{font-spec}{\{[<options>]<font>\}}
+\end{beschreibung}
+\begin{beispiel}
+ \chemsetup[chemformula]{font-spec={Linux Biolinum O}} \sample \\
+ \chemsetup[chemformula]{font-spec={Augie}} \sample \\
+ \chemsetup[chemformula]{font-spec={Latin Modern Sans}} \sample \\
+ \bfseries \sample \normalfont
+\end{beispiel}
+\secidx*{Format and Font}
+
+\section{Usage In Math Equations}\secidx{Math Environments}
+The \cmd{ch} command can be used inside math equations. It recognizes
+\lstinline+\\+ and \lstinline+&+ and passes them on. However, you can't use
+the optional arguments of \lstinline+\\+ inside \cmd{ch}.
+\begin{beispiel}
+ \begin{align}
+ \ch{
+ H2O & ->[a] H2SO4 \\
+ Cl2 & ->[x][y] CH4
+ }
+ \end{align}
+ \begin{align*}
+ \ch{
+ RNO2 &<=>[ + e- ] RNO2^{-.} \\
+ RNO2^{-.} &<=>[ + e- ] RNO2^2-
+ }
+ \end{align*}
+\end{beispiel}
+\secidx*{Math Environments}
+
+\section{Further Examples}
+This section presents some examples of a possible usage.
+
+\begin{beispiel}
+ \begin{reaction}[Synthese von Alkanen]
+ !(Synthesegas)( $n$ CO + $(2n+1)$ H2 )
+ ->[\SI{200}{\celsius}][\[CoNi\]]
+ C_{$n$}H_{$2n+2$} + $n$ H2O
+ \end{reaction}
+\end{beispiel}
+
+\begin{beispiel}
+ \begin{reactions*}
+ "a)" && CH4 + Cl2 &-> CH3Cl + HCl && "{\small Chlormethan/Methylchlorid}" \\
+ "b)" && CH3Cl + Cl2 &-> CH2Cl2 + HCl && "{\small Dichlormethan/Methylenchlorid}" \\
+ "c)" && CH2Cl2 + Cl2 &-> CHCl3 + HCl && "{\small Trichlormethan/Chloroform}" \\
+ "d)" && CHCl3 + Cl2 &-> CCl4 + HCl && "{\small Tetrachlormethan/Tetrachlorkohlenstoff}"
+ \end{reactions*}
+\end{beispiel}
+
+\begin{beispiel}
+ \chemsetup[ox]{parse=false}
+ \ch{"\ox{\delm,C}" -{} "\ox{\delp,M}" \qquad ( <-> "\ox{\delp,C}" -{} "\ox{\delm,Br}" )} \\
+ \ch[adduct-space=0pt]{X. + .Y <=> X-Y + Bindungsenergie} \\
+ \ch[name-format=\normalsize]{
+ !(\State{H}{f}\qquad)() !(\textcolor{red}{??})( CH4\gas{} ) +
+ !(\num{0})( 2 O2\gas{} )
+ ->
+ !(\num{-94.3})( CO2\gas{} ) +
+ !(\num{-57.9})( H2O\lqd{} ) +
+ !(\num{-192.1})( "\State{H}" )
+ }
+\end{beispiel}
+
+\begin{beispiel}
+ \newcommand\cstack[1]{%
+ \clap{%
+ \begin{tabular}{c}
+ #1
+ \end{tabular}
+ }%
+ }
+ \begin{reactions*}
+ CH3MgBr + "\ox*{1,Cu}" X &-> "\glqq" CH3 "\ox*{1,Cu}\grqq" + MgBrX "\qquad X~$=$~Br,I,CN" \\
+ 2 MeLi + CuI &-> !(\cstack{Dimethylcuprat\\(Gilmann-Cuprat)})( Me2CuLi ) + Li
+ \end{reactions*}
+\end{beispiel}
+
+\begin{beispiel}
+ % needs `chemfig'
+ \begin{reactions*}
+ H3C-CH3 + Cl2 &->[$\Delta$][$h\nu$] H3CCH2Cl + HCl & &"\Enthalpy{-27.1}" \\
+ H3C-CH3 + "\Lewis{0.,Cl}" &-> H3CCH2 "\Lewis{0.,\vphantom{H}}" + HCl & &"\Enthalpy{-5.0}" \\
+ H3C-CH2 "\Lewis{0.,\vphantom{H}}" + Cl2 &-> H3CCH2Cl + "\Lewis{0.,Cl}" & &"\Enthalpy{-23.0}"
+ \end{reactions*}
+\end{beispiel}
+
+The following example shows how the cancelling of compounds could be done%
+\footnote{Inspired by a question on TeX.SE: \url{http://tex.stackexchange.com/q/30118/5049}}.
+\begin{beispiel}
+ % needs `cancel'
+ \begin{align*}
+ \ch{\cancel{HCOOH\aq} + H2O\lqd{} &<=> H3O^+\aq{} + \cancel{HCOO^-\aq}} \\
+ \ch{\cancel{HCOO^-\aq} + H2O\lqd{} &<=> \cancel{HCOOH\aq} + OH^-\aq}\\[-1ex]
+ \cline{1-2}
+ \ch{H2O\lqd{} + H2O\lqd{} &<=> H3O^+\aq{} + OH^-\aq}
+ \end{align*}
+\end{beispiel}
+
+\printbibliography
+
+{\catcode`\^=11 \catcode`\#=11
+\printindex}
+
+\end{document}