started background.tex

src/chapters/background.tex

@@ -1,3 +1,17 @@
 \section{Background}
 
+\subsection{Outermost orbit and valence electrons}
+As is common knowledge, everything is made out of atoms, every living creature and every unanimated object. An atom is made out of three subatomic particles. The protons (which have a positive electric charge) and the neutrons constitute the nuclei of the atom. The electrons, carrying a negative charge, orbit around the nucleus in distinct orbits.
+
+By observing the figure \ref{fig:atom-structure}, it is possible to distinguish two important types of electrons: the inner electrons, which are
+
+
+\begin{figure}[h]
+    \centering
+    \input{TikZ/atom-structure.tex}
+    \caption{The orbits of an atom.}
+    \label{fig:atom-structure}
+\end{figure}
+
+
 \todo{Here talk about the electrons and stuff}

src/main.tex

@@ -18,6 +18,8 @@
 
 \input{chapters/introduction.tex}
 
+\input{chapters/background.tex}
+
 \input{chapters/PTC-type.tex}