Stop last column of multicolumn table from leaving right side of page

Question

The code below leads to this table:

where the right hand side goes off the page but the last column of data is not displayed. The table should fit on the page -- it is not too wide, except that the right column is inexplicably extended off of the page. For instance, the caption is wider than where the last column of data should be, and that caption easily fits in the page. What am I missing?

\begin{table}[ht]
  \caption{Site and structural characterization data for the samples in this study.}
  \begin{center}
\begin{tabular}{c c c c c c}
\hline 
\multicolumn{1}{p{1.5cm}}{\centering Sample}
& \multicolumn{1}{p{1.5cm}}{\centering Si/Sn \\Ratio \\ (AAS)$^a$\\}
& \multicolumn{1}{p{1.5cm}}{\centering Si/Sn\\ Ratio \\ (EDS)$^b$}
& \multicolumn{1}{p{1.5cm}}{\centering V\textsubscript{ads, micro}\\(cm$^3$ g\textsuperscript{-1})}
& \multicolumn{1}{p{1.5cm}}{\centering DRUV \\Band \\ Center\\ (nm)$^e$}
& \multicolumn{1}{p{1.5cm}}{\centering DRUV\\ Edge \\Energy\\ (eV)$^e$} \\\hline
 Sn-CHA-F-60&59&65&0.16$^c$&219&4.33\\
Sn-CHA-F-70&70&65&0.15$^c$&223&4.12\\
Sn-Beta-F-116&116&122&0.23$^d$&222&4.23\\
 Sn-xerogel&110&130&0.02$^c$&245&4.37\\
Si-CHA-F&n.m.*&n.m.*&0.23$^c$&n.m.*&n.m.*\\\hline
\multicolumn{6}{l}{$^a$Bulk composition determined by atomic absorption spectroscopy (AAS).} \\
\multicolumn{6}{l}{$^b$Composition determined by energy dispersive X-ray spectroscopy (EDS).} \\
\multicolumn{6}{l}{$^c$Micropore volume determined from Ar adsorption isotherms (87 K). } \\
\multicolumn{6}{l}{$^d$Micropore volume determined from N$_2$ adsorption isotherms (77 K). } \\
\multicolumn{6}{l}{$^e$Diffuse reflectance UV-Vis spectra (band center at maximum F(R) intensity) and Tauc plots for samples after dehydration at 523 K (Section \ref{sec: chas5}). } \\
\multicolumn{6}{l}{*n. m., not measured} \\
\end{tabular}
  \end{center}
  \label{ta: cd3cn1}
\end{table}

Answer 1

Your table notes were too long; split them and all is well. Also, use \centering in tables and figures.

\documentclass{article}


\begin{document}
\begin{table}[ht]
  \caption{Site and structural characterization data for the samples in this study.}
  \centering
\begin{tabular}{c c c c c c}
\hline 
\multicolumn{1}{p{1.5cm}}{\centering Sample}
& \multicolumn{1}{p{1.5cm}}{\centering Si/Sn \\Ratio \\ (AAS)$^a$\\}
& \multicolumn{1}{p{1.5cm}}{\centering Si/Sn\\ Ratio \\ (EDS)$^b$}
& \multicolumn{1}{p{1.5cm}}{\centering V\textsubscript{ads, micro}\\(cm$^3$ g\textsuperscript{-1})}
& \multicolumn{1}{p{1.5cm}}{\centering DRUV \\Band \\ Center\\ (nm)$^e$}
& \multicolumn{1}{p{1.5cm}}{\centering DRUV\\ Edge \\Energy\\ (eV)$^e$} \\\hline
 Sn-CHA-F-60&59&65&0.16$^c$&219&4.33\\
Sn-CHA-F-70&70&65&0.15$^c$&223&4.12\\
Sn-Beta-F-116&116&122&0.23$^d$&222&4.23\\
 Sn-xerogel&110&130&0.02$^c$&245&4.37\\
Si-CHA-F&n.m.*&n.m.*&0.23$^c$&n.m.*&n.m.*\\\hline
\multicolumn{6}{l}{$^a$Bulk composition determined by atomic absorption spectroscopy (AAS).} \\
\multicolumn{6}{l}{$^b$Composition determined by energy dispersive X-ray spectroscopy (EDS).} \\
\multicolumn{6}{l}{$^c$Micropore volume determined from Ar adsorption isotherms (87 K). } \\
\multicolumn{6}{l}{$^d$Micropore volume determined from N$_2$ adsorption isotherms (77 K). } \\
\multicolumn{6}{l}{$^e$Diffuse reflectance UV-Vis spectra (band center at maximum F(R) intensity)}\\
\multicolumn{6}{l}{\hspace{3ex} and Tauc plots for samples after dehydration at 523 K (Section \ref{sec: chas5}). } \\
\multicolumn{6}{l}{*n. m., not measured} \\
\end{tabular}
  \label{ta: cd3cn1}
\end{table}
\end{document}

Answer 2

I would like to suggest that you (a) use a tabularx environment instead of a tabular environment, (b) use the machinery of the threeparttable -- especially the \tnote macros and the tablenotes environment, and (c) the \si and \SI macros of the siunitx package to typeset scientific units.

\documentclass{article}
\usepackage{tabularx,booktabs,siunitx}
\newcolumntype{C}{>{\centering\arraybackslash}X} % centered "X" columns    
\usepackage[flushleft]{threeparttable}
\renewcommand\TPTtagStyle{\textit} % italic footnote markers

\begin{document}

\begin{table}[ht]
\begin{threeparttable}
\caption{Site and structural characterization data for the samples in this study.} 
\label{ta:cd3cn1}

\begin{tabularx}{\textwidth}{@{} l CCCCC @{}}
\toprule 
Sample
& Si/Sn Ratio  (AAS)\tnote{a}
& Si/Sn Ratio  (EDS)\tnote{b}
& V\textsubscript{ads,micro} (\si{\centi\meter\cubed} \si{\gram\tothe{-1}})
& DRUV Band Center (\si{\nano\meter})\tnote{e}
& DRUV Edge Energy (\si{\electronvolt})\tnote{e} \\
\midrule
Sn-CHA-F-60   & 59  & 65  &0.16\tnote{c} &219  &4.33\\
Sn-CHA-F-70   & 70  & 65  &0.15\tnote{c} &223  &4.12\\
Sn-Beta-F-116 &116  &122  &0.23\tnote{d} &222  &4.23\\
Sn-xerogel    &110  &130  &0.02\tnote{c} &245  &4.37\\
Si-CHA-F      &n.m.*&n.m.*&0.23\tnote{c} &n.m.*&n.m.*\\
\bottomrule
\end{tabularx}

\smallskip
\begin{tablenotes}
\item[a] Bulk composition determined by atomic absorption spectroscopy (AAS).
\item[b] Composition determined by energy dispersive X-ray spectroscopy (EDS).
\item[c] Micropore volume determined from Ar adsorption isotherms 
         (\SI{87}{\kelvin}). 
\item[d] Micropore volume determined from N\textsubscript{2} adsorption 
         isotherms (\SI{77}{\kelvin}). 
\item[e] Diffuse reflectance UV-Vis spectra (band center at maximum F(R) 
         intensity) and Tauc plots for samples after dehydration at 
         \SI{523}{\kelvin} (Section \ref{sec:chas5}). 
\end{tablenotes}
n.m.* not measured
\end{threeparttable}
\end{table}
\end{document}