\documentclass[10pt,a4paper]{scrartcl}
\usepackage[centertags]{amsmath}
\usepackage{graphicx,psfrag,epsfig,color,units}
\usepackage{amssymb,amstext}
\usepackage[utf8]{inputenc}
\usepackage[ngerman]{babel}
\usepackage{lmodern}
\usepackage{microtype}
\usepackage{pdfpages,url}
\usepackage[T1]{fontenc}
\usepackage{chemfig}

\setlength{\tabcolsep}{0.1cm}
\setlength{\textwidth}{16.8cm}
\setlength{\topmargin}{-2.2cm}
\setlength{\oddsidemargin}{-0.5cm}
\setlength{\evensidemargin}{-0.5cm}

\renewcommand\textheight{27cm}
\renewcommand{\labelitemi}{--}

\newcommand{\ee}[1]{\,\cdot 10^{#1}}
\newcommand{\e}[1]{10^{#1}}
\newcommand{\C}{\ensuremath{^\circ \mathrm{C}}\xspace}
\newcommand{\Ohm}{\ensuremath{\Omega}\xspace}

%\allowdisplaybreaks[1]
\parindent0cm

\begin{document}
\section{Textbereich}
Vis enim, ut mihi saepe dixisti, quoniam, quae pueris aut adulescentulis nobis ex commentariolis nostris incohata ac rudia exciderunt, vix sunt hac aetate digna et hoc usu, quem ex causis, quas diximus, tot tantisque consecuti sumus, aliquid eisdem de rebus politius a nobis perfectiusque proferri; solesque non numquam hac de re a me in disputationibus nostris dissentire, quod ego eruditissimorum hominum artibus eloquentiam contineri statuam, tu autem illam ab elegantia doctrinae segregandam putes et in quodam ingeni atque exercitationis genere ponendam.

Ac mihi quidem saepe numero in summos homines ac summis ingeniis praeditos intuenti quaerendum esse visum est quid esset cur plures in omnibus rebus quam in dicendo admirabiles exstitissent; nam quocumque te animo et cogitatione converteris, permultos excellentis in quoque genere videbis non mediocrium artium, sed prope maximarum (Zit. aus \cite{Cicero}).

\section{Wir schreiben mathematische Formeln}
Mathematische Formeln mit \LaTeX. Pythagoras im rechtwinkligen Dreieck
	\[ a^2+b^2=c^2
\]
sieht im \TeX -File so aus:
\begin{verbatim}
\[ a^2+b^2=c^2
\]
\end{verbatim}

oder die Gleichungen von \textsc{Maxwell}:

\begin{align}
		\vec \nabla \cdot \vec 	D&=\rho \\
		\vec \nabla \cdot \vec 	B&= 0 \\
		\vec \nabla \times \vec E&= -\cfrac{\partial\vec B}{\partial t} \\
		\vec \nabla \times \vec H&= \vec j_l + \cfrac{\partial\vec D}{\partial t}
\end{align}

\begin{verbatim}
\begin{align}
		\vec \nabla \cdot \vec  D&=\rho \\
		\vec \nabla \cdot \vec  B&= 0 \\
		\vec \nabla \times \vec E&= -\cfrac{\partial\vec B}{\partial t} \\
		\vec \nabla \times \vec H&= \vec j_l + \cfrac{\partial\vec D}
		{\partial t}
\end{align}
\end{verbatim}

\section{Chemie}
% \chemfig{C(-[2]H)(-[4]H)(-[6]H)-\lewis{260,Cl}}\hskip4cm %LEWIS nicht mehr vorhanden
\chemfig{[:100]-C (=[::60] O)-[::-60] O-[::-60]C(=[::60] O)-[::-60]}

\begin{thebibliography}{99}
\bibitem{Cicero} Cicero, M. Tullius: \emph{De oratore.} Liber primus. \newline 
\url{http://www.thelatinlibrary.com/cicero/oratore1.shtml} (22.8.2014).

\bibitem{Sexl} Sexl/Raab/Streeruwitz: \emph{Der Weg zur modernen Physik.}
Sauerländer; Frankfurt/Main: Diesterweg 1990. ISBN: 3425050613.

\bibitem{Grentz}
Grentz, Wolfgang et. al.: \emph{Physik anwenden und verstehen.} Orell Füssli, 2008.

\bibitem{Jackson}
Jackson, John D.: \emph{Klassische Elektrodynamik.} De Gruyter; Auflage: 4., 2006.

\end{thebibliography}
\end{document}