\begin{table}%t3
  \caption{Initial abundances in mass fraction.}
  \label{tab:Ab}
  %\centering
\small
  \begin{tabular}{cccc}
    \hline \hline
    Element & Abundance & Element & Abundance \\
    \hline
    &&& \\[-8pt]
    \el{H}{1}   & 0.754     & \el{F}{19}  & 1.53e$-$8 \\
    \el{He}{3}  & 2.93e$-$5   & \el{Ne}{20} & 5.30e$-$5 \\
    \el{He}{4}  & 0.245     & \el{Ne}{21} & 5.00e$-$8 \\
    \el{C}{12}  & 3.50e$-$5   & \el{Ne}{22} & 4.72e$-$6 \\
    \el{C}{13}  & 1.47e$-$7   & \el{Na}{23} & 3.30e$-$7 \\
    \el{N}{14}  & 1.03e$-$5   & \el{Mg}{24} & 1.68e$-$5 \\
    \el{N}{15}  & 1.58e$-$8   & \el{Mg}{25} & 2.10e$-$6 \\
    \el{O}{16}  & 3.00e$-$4   & \el{Mg}{26} & 2.10e$-$6 \\
    \el{O}{17}  & 1.31e$-$7   & \el{Al}{27} & 9.00e$-$7 \\
    \el{O}{18}  & 7.45e$-$6   & \el{Si}{28} & 2.56e$-$5 \\
    \hline
  \end{tabular}
\end{table}