Update main.tex to include additional subsections for various groups of elements and remove the date from the title. Update main.pdf to reflect these changes.

main.tex

@@ -17,18 +17,32 @@
 % Document information
 \title{Chemistry Vocabulary}
 \author{}
-\date{\today}
+\date{}
 
 \begin{document}
 
 \maketitle
 
-\section{Introduction}
+\section*{Introduction}
-
-% Add your content here
 
 \section{Elements and elementary substances}
 
+\subsection{Alkali metals}
+
+\subsection{Alkaline earth metals}
+
+\subsection{Transition metals}
+
+\subsection{Post-transition metals}
+
+\subsection{Metalloids}
+
+\subsection{Halogen}
+
+\subsection{Noble gases}
+
+\subsection{Other Nonmetals}
+
 \section{Acids and bases}
 
 \section{Ions}